/*
 * Modified by ScyllaDB
 * Copyright (C) 2015-present ScyllaDB
 */

/*
 * SPDX-License-Identifier: (LicenseRef-ScyllaDB-Source-Available-1.0 and Apache-2.0)
 */

#include "db/schema_tables.hh"

#include "service/migration_manager.hh"
#include "service/storage_proxy.hh"
#include "gms/feature_service.hh"
#include "partition_slice_builder.hh"
#include "dht/i_partitioner.hh"
#include "system_keyspace.hh"
#include "query-result-set.hh"
#include "query-result-writer.hh"
#include "schema/schema_builder.hh"
#include "map_difference.hh"
#include "utils/assert.hh"
#include "utils/UUID_gen.hh"
#include "utils/to_string.hh"
#include <algorithm>
#include <ranges>
#include <seastar/coroutine/all.hh>
#include "utils/log.hh"
#include "frozen_schema.hh"
#include "schema/schema_registry.hh"
#include "mutation_query.hh"
#include "system_keyspace.hh"
#include "system_distributed_keyspace.hh"
#include "cql3/query_processor.hh"
#include "cql3/cql3_type.hh"
#include "cql3/functions/functions.hh"
#include "cql3/functions/user_function.hh"
#include "cql3/functions/user_aggregate.hh"
#include "cql3/expr/evaluate.hh"
#include "cql3/expr/expr-utils.hh"
#include "cql3/util.hh"
#include "types/list.hh"
#include "types/set.hh"
#include "replica/tablets.hh"

#include "db/marshal/type_parser.hh"
#include "db/config.hh"
#include "db/extensions.hh"
#include "utils/hashers.hh"

#include <fmt/ranges.h>

#include <seastar/util/noncopyable_function.hh>
#include <seastar/rpc/rpc_types.hh>
#include <seastar/core/coroutine.hh>
#include <seastar/core/future.hh>
#include <seastar/coroutine/parallel_for_each.hh>
#include <seastar/core/loop.hh>
#include <seastar/core/on_internal_error.hh>

#include <boost/algorithm/string/predicate.hpp>
#include <boost/range/join.hpp>

#include "compaction/compaction_strategy.hh"
#include "view_info.hh"
#include "cql_type_parser.hh"
#include "db/timeout_clock.hh"
#include "replica/database.hh"
#include "data_dictionary/user_types_metadata.hh"

#include "index/target_parser.hh"
#include "lang/lua.hh"
#include "lang/manager.hh"

#include "idl/mutation.dist.hh"
#include "idl/mutation.dist.impl.hh"
#include "db/system_keyspace.hh"
#include "cql3/untyped_result_set.hh"
#include "cql3/functions/user_aggregate.hh"

#include "cql3/CqlParser.hpp"
#include "cql3/expr/expression.hh"
#include "cql3/column_identifier.hh"
#include "cql3/column_specification.hh"
#include "types/types.hh"
#include "mutation/async_utils.hh"

using namespace db;
using namespace std::chrono_literals;


static logging::logger diff_logger("schema_diff");


/** system.schema_* tables used to store keyspace/table/type attributes prior to C* 3.0 */
namespace db {
namespace {
    const auto set_use_schema_commitlog = schema_builder::register_static_configurator([](const sstring& ks_name, const sstring& cf_name, schema_static_props& props) {
        if (ks_name == schema_tables::NAME) {
            props.enable_schema_commitlog();
        }
    });
    const auto set_group0_table_options =
        schema_builder::register_static_configurator([](const sstring& ks_name, const sstring& cf_name, schema_static_props& props) {
            if (ks_name == schema_tables::NAME) {
                // all schema tables are group0 tables
                props.is_group0_table = true;
            }
        });
}

schema_ctxt::schema_ctxt(const db::config& cfg, std::shared_ptr<data_dictionary::user_types_storage> uts,
                         const gms::feature_service& features, replica::database* db)
    : _db(db)
    , _features(features)
    , _extensions(cfg.extensions())
    , _murmur3_partitioner_ignore_msb_bits(cfg.murmur3_partitioner_ignore_msb_bits())
    , _schema_registry_grace_period(cfg.schema_registry_grace_period())
    , _user_types(std::move(uts))
{}

schema_ctxt::schema_ctxt(replica::database& db)
    : schema_ctxt(db.get_config(), db.as_user_types_storage(), db.features(), &db)
{}

schema_ctxt::schema_ctxt(distributed<replica::database>& db)
    : schema_ctxt(db.local())
{}

schema_ctxt::schema_ctxt(distributed<service::storage_proxy>& proxy)
    : schema_ctxt(proxy.local().get_db())
{}

namespace schema_tables {

logging::logger slogger("schema_tables");

const sstring version = "3";

using computed_columns_map = std::unordered_map<bytes, column_computation_ptr>;
static computed_columns_map get_computed_columns(const schema_mutations& sm);

static std::vector<column_definition> create_columns_from_column_rows(
                const schema_ctxt& ctxt,
                const query::result_set& rows, const sstring& keyspace,
                const sstring& table, bool is_super, column_view_virtual is_view_virtual, const computed_columns_map& computed_columns);


static std::vector<index_metadata> create_indices_from_index_rows(const query::result_set& rows,
                                const sstring& keyspace,
                                const sstring& table);

static index_metadata create_index_from_index_row(const query::result_set_row& row,
                     sstring keyspace,
                     sstring table);

static void add_column_to_schema_mutation(schema_ptr, const column_definition&,
                api::timestamp_type, mutation&);

static void add_computed_column_to_schema_mutation(schema_ptr, const column_definition&,
                api::timestamp_type, mutation&);

static void add_index_to_schema_mutation(schema_ptr table,
                const index_metadata& index, api::timestamp_type timestamp,
                mutation& mutation);

static void drop_column_from_schema_mutation(schema_ptr schema_table, schema_ptr table,
                const sstring& column_name, long timestamp,
                std::vector<mutation>&);

static void drop_index_from_schema_mutation(schema_ptr table,
                const index_metadata& column, long timestamp,
                std::vector<mutation>& mutations);

static future<schema_ptr> create_table_from_table_row(
                distributed<service::storage_proxy>&,
                const query::result_set_row&);

static void prepare_builder_from_table_row(const schema_ctxt&, schema_builder&, const query::result_set_row&);

using namespace v3;

using days = std::chrono::duration<int, std::ratio<24 * 3600>>;

static future<> save_system_schema_to_keyspace(cql3::query_processor& qp, const sstring & ksname) {
    auto ks = qp.db().find_keyspace(ksname);
    auto ksm = ks.metadata();

    // delete old, possibly obsolete entries in schema tables
    co_await coroutine::parallel_for_each(all_table_infos(schema_features::full()), [&qp, ksm] (table_info ti) -> future<> {
        auto deletion_timestamp = system_keyspace::schema_creation_timestamp() - 1;
        co_await qp.execute_internal(format("DELETE FROM {}.{} USING TIMESTAMP {} WHERE keyspace_name = ?", NAME, ti.name,
            deletion_timestamp), { ksm->name() }, cql3::query_processor::cache_internal::yes).discard_result();
    });
    {
        auto mvec  = make_create_keyspace_mutations(qp.db().features().cluster_schema_features(), ksm, system_keyspace::schema_creation_timestamp(), true);
        co_await qp.proxy().mutate_locally(std::move(mvec), tracing::trace_state_ptr());
    }
}

future<> save_system_schema(cql3::query_processor& qp) {
    co_await save_system_schema_to_keyspace(qp, schema_tables::NAME);
    // #2514 - make sure "system" is written to system_schema.keyspaces.
    co_await save_system_schema_to_keyspace(qp, system_keyspace::NAME);
}

namespace v3 {

schema_ptr keyspaces() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, KEYSPACES), NAME, KEYSPACES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {},
        // regular columns
        {
            {"durable_writes", boolean_type},
            {"replication", map_type_impl::get_instance(utf8_type, utf8_type, false)},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "keyspace definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr scylla_keyspaces() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, SCYLLA_KEYSPACES), NAME, SCYLLA_KEYSPACES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {},
        // regular columns
        {
            {"storage_type", utf8_type},
            {"storage_options", map_type_impl::get_instance(utf8_type, utf8_type, false)},
            {"initial_tablets", int32_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "scylla-specific information for keyspaces"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr tables() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, TABLES), NAME, TABLES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"table_name", utf8_type}},
        // regular columns
        {
         {"bloom_filter_fp_chance", double_type},
         {"caching", map_type_impl::get_instance(utf8_type, utf8_type, false)},
         {"comment", utf8_type},
         {"compaction", map_type_impl::get_instance(utf8_type, utf8_type, false)},
         {"compression", map_type_impl::get_instance(utf8_type, utf8_type, false)},
         {"crc_check_chance", double_type},
         // dclocal_read_repair_chance has been deprecated, preserved to be
         // backward compatible
         {"dclocal_read_repair_chance", double_type},
         {"default_time_to_live", int32_type},
         {"extensions", map_type_impl::get_instance(utf8_type, bytes_type, false)},
         {"flags", set_type_impl::get_instance(utf8_type, false)}, // SUPER, COUNTER, DENSE, COMPOUND
         {"gc_grace_seconds", int32_type},
         {"id", uuid_type},
         {"max_index_interval", int32_type},
         {"memtable_flush_period_in_ms", int32_type},
         {"min_index_interval", int32_type},
         // read_repair_chance has been deprecated, preserved to be backward
         // compatible
         {"read_repair_chance", double_type},
         {"speculative_retry", utf8_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "table definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

// Holds Scylla-specific table metadata.
schema_ptr scylla_tables(schema_features features) {
    static thread_local schema_ptr schemas[2][2]{};

    bool has_group0_schema_versioning = features.contains(schema_feature::GROUP0_SCHEMA_VERSIONING);
    bool has_in_memory = features.contains(schema_feature::IN_MEMORY_TABLES);

    schema_ptr& s = schemas[has_in_memory][has_group0_schema_versioning];
    if (!s) {
        auto id = generate_legacy_id(NAME, SCYLLA_TABLES);
        auto sb = schema_builder(NAME, SCYLLA_TABLES, std::make_optional(id))
            .with_column("keyspace_name", utf8_type, column_kind::partition_key)
            .with_column("table_name", utf8_type, column_kind::clustering_key)
            .with_column("version", uuid_type);

        sb.with_column("cdc", map_type_impl::get_instance(utf8_type, utf8_type, false));

        // PER_TABLE_PARTITIONERS
        sb.with_column("partitioner", utf8_type);

        if (has_in_memory) {
            sb.with_column("in_memory", boolean_type);
        }

        if (has_group0_schema_versioning) {
            // If true, this table's latest schema was committed by group 0.
            // In this case `version` column is non-null and will be used for `schema::version()` instead of calculating a hash.
            //
            // If false, this table's latest schema was committed outside group 0 (e.g. during RECOVERY mode).
            // In this case `version` is null and `schema::version()` will be a hash.
            //
            // If null, this is either a system table, or the latest schema was committed
            // before the GROUP0_SCHEMA_VERSIONING feature was enabled (either inside or outside group 0).
            // In this case, for non-system tables, `version` is null and `schema::version()` will be a hash.
            sb.with_column("committed_by_group0", boolean_type);
        }

        // It is safe to add the `tablets` column unconditionally,
        // since it is written to only after the cluster feature is enabled.
        sb.with_column("tablets", map_type_impl::get_instance(utf8_type, utf8_type, false));

        sb.with_hash_version();
        s = sb.build();
    }

    return s;
}

// The "columns" table lists the definitions of all columns in all tables
// and views. Its schema needs to be identical to the one in Cassandra because
// it is the API through which drivers inspect the list of columns in a table
// (e.g., cqlsh's "DESCRIBE TABLE" and "DESCRIBE MATERIALIZED VIEW" get their
// information from the columns table).
// The "view_virtual_columns" table is an additional table with exactly the
// same schema (both are created by columns_schema()), but has a separate
// list of "virtual" columns. Those are used in materialized views for keeping
// rows without data alive (see issue #3362). These virtual columns cannot be
// listed in the regular "columns" table, otherwise the "DESCRIBE MATERIALIZED
// VIEW" would list them - while it should only list real, selected, columns.

static schema_ptr columns_schema(const char* columns_table_name) {
    schema_builder builder(generate_legacy_id(NAME, columns_table_name), NAME, columns_table_name,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"table_name", utf8_type},{"column_name", utf8_type}},
        // regular columns
        {
         {"clustering_order", utf8_type},
         {"column_name_bytes", bytes_type},
         {"kind", utf8_type},
         {"position", int32_type},
         {"type", utf8_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "column definitions"
        );
    return builder.with_hash_version().build();
}
schema_ptr columns() {
    static thread_local auto schema = columns_schema(COLUMNS);
    return schema;
}
schema_ptr view_virtual_columns() {
    static thread_local auto schema = columns_schema(VIEW_VIRTUAL_COLUMNS);
    return schema;
}

const std::unordered_set<table_id>& schema_tables_holding_schema_mutations() {
    static const std::unordered_set<table_id> table_ids = [] {
        std::unordered_set<table_id> ids;
        for (auto&& s : {
                tables(),
                views(),
                columns(),
                view_virtual_columns(),
                computed_columns(),
                dropped_columns(),
                indexes(),
                scylla_tables(),
                db::system_keyspace::legacy::column_families(),
                db::system_keyspace::legacy::columns(),
                db::system_keyspace::legacy::triggers()}) {
            SCYLLA_ASSERT(s->clustering_key_size() > 0);
            auto&& first_column_name = s->clustering_column_at(0).name_as_text();
            SCYLLA_ASSERT(first_column_name == "table_name"
                || first_column_name == "view_name"
                || first_column_name == "columnfamily_name");
            ids.emplace(s->id());
        }
        return ids;
    }();
    return table_ids;
};

// Computed columns are a special kind of columns. Rather than having their value provided directly
// by the user, they are computed - possibly from other column values. This table stores which columns
// for a given table are computed, and a serialized computation itself. Full column information is stored
// in the `columns` table, this one stores only entries for computed columns, so it will be empty for tables
// without any computed columns defined in the schema. `computation` is a serialized blob and its format
// is defined in column_computation.hh and system_schema docs.
//
static schema_ptr computed_columns_schema(const char* columns_table_name) {
    schema_builder builder(generate_legacy_id(NAME, columns_table_name), NAME, columns_table_name,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"table_name", utf8_type}, {"column_name", utf8_type}},
        // regular columns
        {{"computation", bytes_type}},
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "computed columns"
        );
    return builder.with_hash_version().build();
}

schema_ptr computed_columns() {
    static thread_local auto schema = computed_columns_schema(COMPUTED_COLUMNS);
    return schema;
}

schema_ptr dropped_columns() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, DROPPED_COLUMNS), NAME, DROPPED_COLUMNS,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"table_name", utf8_type},{"column_name", utf8_type}},
        // regular columns
        {
         {"dropped_time", timestamp_type},
         {"type", utf8_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "dropped column registry"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr triggers() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, TRIGGERS), NAME, TRIGGERS,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"table_name", utf8_type},{"trigger_name", utf8_type}},
        // regular columns
        {
         {"options", map_type_impl::get_instance(utf8_type, utf8_type, false)},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "trigger definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr views() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, VIEWS), NAME, VIEWS,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"view_name", utf8_type}},
        // regular columns
        {
         {"base_table_id", uuid_type},
         {"base_table_name", utf8_type},
         {"where_clause", utf8_type},
         {"bloom_filter_fp_chance", double_type},
         {"caching", map_type_impl::get_instance(utf8_type, utf8_type, false)},
         {"comment", utf8_type},
         {"compaction", map_type_impl::get_instance(utf8_type, utf8_type, false)},
         {"compression", map_type_impl::get_instance(utf8_type, utf8_type, false)},
         {"crc_check_chance", double_type},
         // dclocal_read_repair_chance has been deprecated, preserved to be
         // backward compatible
         {"dclocal_read_repair_chance", double_type},
         {"default_time_to_live", int32_type},
         {"extensions", map_type_impl::get_instance(utf8_type, bytes_type, false)},
         {"gc_grace_seconds", int32_type},
         {"id", uuid_type},
         {"include_all_columns", boolean_type},
         {"max_index_interval", int32_type},
         {"memtable_flush_period_in_ms", int32_type},
         {"min_index_interval", int32_type},
         // read_repair_chance has been deprecated, preserved to be backward
         // compatible
         {"read_repair_chance", double_type},
         {"speculative_retry", utf8_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "view definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr indexes() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, INDEXES), NAME, INDEXES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"table_name", utf8_type},{"index_name", utf8_type}},
        // regular columns
        {
         {"kind", utf8_type},
         {"options", map_type_impl::get_instance(utf8_type, utf8_type, false)},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "secondary index definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr types() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, TYPES), NAME, TYPES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"type_name", utf8_type}},
        // regular columns
        {
         {"field_names", list_type_impl::get_instance(utf8_type, false)},
         {"field_types", list_type_impl::get_instance(utf8_type, false)},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "user defined type definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr functions() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, FUNCTIONS), NAME, FUNCTIONS,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"function_name", utf8_type}, {"argument_types", list_type_impl::get_instance(utf8_type, false)}},
        // regular columns
        {
         {"argument_names", list_type_impl::get_instance(utf8_type, false)},
         {"body", utf8_type},
         {"language", utf8_type},
         {"return_type", utf8_type},
         {"called_on_null_input", boolean_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "user defined function definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr aggregates() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, AGGREGATES), NAME, AGGREGATES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {{"aggregate_name", utf8_type}, {"argument_types", list_type_impl::get_instance(utf8_type, false)}},
        // regular columns
        {
         {"final_func", utf8_type},
         {"initcond", utf8_type},
         {"return_type", utf8_type},
         {"state_func", utf8_type},
         {"state_type", utf8_type},
        },
        // static columns
        {},
        // regular column name type
        utf8_type,
        // comment
        "user defined aggregate definitions"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr scylla_aggregates() {
    static thread_local auto schema = [] {
        schema_builder builder(generate_legacy_id(NAME, SCYLLA_AGGREGATES), NAME, SCYLLA_AGGREGATES,
        // partition key
        {{"keyspace_name", utf8_type}},
        // clustering key
        {
            {"aggregate_name", utf8_type}, 
            {"argument_types", list_type_impl::get_instance(utf8_type, false)}
        },
        //regular columns
        {
            {"reduce_func", utf8_type},
            {"state_type", utf8_type},
        },
        //static columns,
        {},
        // regular column name type
        utf8_type,
        // comment
        "scylla-specific information for user defined aggregates"
        );
        return builder.with_hash_version().build();
    }();
    return schema;
}

schema_ptr scylla_table_schema_history() {
    static thread_local auto s = [] {
        schema_builder builder(db::system_keyspace::NAME, SCYLLA_TABLE_SCHEMA_HISTORY, generate_legacy_id(db::system_keyspace::NAME, SCYLLA_TABLE_SCHEMA_HISTORY));
        builder.with_column("cf_id", uuid_type, column_kind::partition_key);
        builder.with_column("schema_version", uuid_type, column_kind::clustering_key);
        builder.with_column("column_name", utf8_type, column_kind::clustering_key);
        builder.with_column("clustering_order", utf8_type);
        builder.with_column("column_name_bytes", bytes_type);
        builder.with_column("kind", utf8_type);
        builder.with_column("position", int32_type);
        builder.with_column("type", utf8_type);
        builder.set_comment("Scylla specific table to store a history of column mappings "
            "for each table schema version upon an CREATE TABLE/ALTER TABLE operations");
        return builder.with_hash_version().build(schema_builder::compact_storage::no);
    }();
    return s;
}

}

static
mutation
redact_columns_for_missing_features(mutation&& m, schema_features features) {
    return std::move(m);
    // The following code is needed if there are new schema features that require redaction.
#if 0
    if (m.schema()->cf_name() != SCYLLA_TABLES) {
        return std::move(m);
    }
    slogger.debug("adjusting schema_tables mutation due to possible in-progress cluster upgrade");
    // The global schema ptr make sure it will be registered in the schema registry.
    global_schema_ptr redacted_schema{scylla_tables(features)};
    m.upgrade(redacted_schema);
    return std::move(m);
#endif
}

/**
 * Read schema from system keyspace and calculate MD5 digest of every row, resulting digest
 * will be converted into UUID which would act as content-based version of the schema.
 */
future<table_schema_version> calculate_schema_digest(distributed<service::storage_proxy>& proxy, schema_features features, noncopyable_function<bool(std::string_view)> accept_keyspace)
{
    using mutations_generator = coroutine::experimental::generator<mutation>;

    auto map = [&proxy, features, accept_keyspace = std::move(accept_keyspace)] (table_info table) mutable -> mutations_generator {
        auto& db = proxy.local().get_db();
        auto s = db.local().find_schema(table.id);
        auto rs = co_await db::system_keyspace::query_mutations(db, s);
        for (auto&& p : rs->partitions()) {
            auto partition_key = value_cast<sstring>(utf8_type->deserialize(::partition_key(p.mut().key()).get_component(*s, 0)));
            if (!accept_keyspace(partition_key)) {
                continue;
            }
            auto mut = co_await unfreeze_gently(p.mut(), s);
            co_yield redact_columns_for_missing_features(std::move(mut), features);
        }
    };
    auto hash = md5_hasher();
    auto tables = all_table_infos(features);
    {
        for (auto& table: tables) {
            auto gen_mutations = map(table);
            while (auto mut_opt = co_await gen_mutations()) {
                auto& m = *mut_opt;
                feed_hash_for_schema_digest(hash, m, features);
                if (diff_logger.is_enabled(logging::log_level::trace)) {
                    md5_hasher h;
                    feed_hash_for_schema_digest(h, m, features);
                    diff_logger.trace("Digest {} for {}, compacted={}", h.finalize(), m, compact_for_schema_digest(m));
                }
            }
        }
        co_return utils::UUID_gen::get_name_UUID(hash.finalize());
    }
}

future<table_schema_version> calculate_schema_digest(distributed<service::storage_proxy>& proxy, schema_features features)
{
    return calculate_schema_digest(proxy, features, std::not_fn(&is_system_keyspace));
}

static thread_local semaphore the_merge_lock {1};

future<> merge_lock() {
    if (slogger.is_enabled(log_level::trace)) {
        slogger.trace("merge_lock at {}", current_backtrace());
    }
    return smp::submit_to(0, [] { return the_merge_lock.wait(); });
}

future<> merge_unlock() {
    if (slogger.is_enabled(log_level::trace)) {
        slogger.trace("merge_unlock at {}", current_backtrace());
    }
    return smp::submit_to(0, [] { the_merge_lock.signal(); });
}

future<semaphore_units<>> hold_merge_lock() noexcept {
    SCYLLA_ASSERT(this_shard_id() == 0);

    if (slogger.is_enabled(log_level::trace)) {
        slogger.trace("hold_merge_lock at {}", current_backtrace());
    }
    return get_units(the_merge_lock, 1);
}

future<> with_merge_lock(noncopyable_function<future<> ()> func) {
    co_await merge_lock();
    std::exception_ptr ep;
    try {
        co_await func();
    } catch (...) {
        ep = std::current_exception();
    }
    co_await merge_unlock();
    if (ep) {
        std::rethrow_exception(std::move(ep));
    }
}

future<> update_schema_version_and_announce(sharded<db::system_keyspace>& sys_ks, distributed<service::storage_proxy>& proxy, schema_features features, std::optional<table_schema_version> version_from_group0) {
    auto uuid = version_from_group0 ? *version_from_group0 : co_await calculate_schema_digest(proxy, features);
    co_await sys_ks.local().update_schema_version(uuid);
    co_await proxy.local().get_db().invoke_on_all([uuid] (replica::database& db) {
        db.update_version(uuid);
    });
    slogger.info("Schema version changed to {}", uuid);
}

future<std::optional<table_schema_version>> get_group0_schema_version(db::system_keyspace& sys_ks) {
    auto version = co_await sys_ks.get_scylla_local_param_as<utils::UUID>("group0_schema_version");
    if (!version) {
        co_return std::nullopt;
    }
    co_return table_schema_version{*version};
}

future<> recalculate_schema_version(sharded<db::system_keyspace>& sys_ks, distributed<service::storage_proxy>& proxy, gms::feature_service& feat) {
    co_await with_merge_lock([&] () -> future<> {
        auto version_from_group0 = co_await get_group0_schema_version(sys_ks.local());
        co_await update_schema_version_and_announce(sys_ks, proxy, feat.cluster_schema_features(), version_from_group0);
    });
}

future<std::vector<canonical_mutation>> convert_schema_to_mutations(distributed<service::storage_proxy>& proxy, schema_features features)
{
    auto map = [&proxy, features] (table_info table) -> future<std::vector<canonical_mutation>> {
        auto& db = proxy.local().get_db();
        auto s = db.local().find_schema(table.id);
        auto rs = co_await db::system_keyspace::query_mutations(db, s);
        std::vector<canonical_mutation> results;
        results.reserve(rs->partitions().size());
        for (auto&& p : rs->partitions()) {
            auto mut = co_await unfreeze_gently(p.mut(), s);
            auto partition_key = value_cast<sstring>(utf8_type->deserialize(mut.key().get_component(*s, 0)));
            if (is_system_keyspace(partition_key)) {
                continue;
            }
            mut = redact_columns_for_missing_features(std::move(mut), features);
            results.emplace_back(co_await make_canonical_mutation_gently(mut));
        }
        co_return results;
    };
    auto reduce = [] (auto&& result, auto&& mutations) {
        std::move(mutations.begin(), mutations.end(), std::back_inserter(result));
        return std::move(result);
    };
    co_return co_await map_reduce(all_table_infos(features), map, std::vector<canonical_mutation>{}, reduce);
}

std::vector<mutation>
adjust_schema_for_schema_features(std::vector<mutation> schema, schema_features features) {
    for (auto& m : schema) {
        m = redact_columns_for_missing_features(std::move(m), features);
    }
    return schema;
}

static
future<mutation> query_partition_mutation(service::storage_proxy& proxy,
    schema_ptr s,
    lw_shared_ptr<query::read_command> cmd,
    partition_key pkey)
{
    auto dk = dht::decorate_key(*s, pkey);
    auto range = dht::partition_range::make_singular(dk);
    auto res_hit_rate = co_await proxy.query_mutations_locally(s, std::move(cmd), range, db::no_timeout, tracing::trace_state_ptr{});
    auto&& [res, hit_rate] = res_hit_rate;
    auto&& partitions = res->partitions();
    if (partitions.size() == 0) {
        co_return mutation(s, std::move(dk));
    } else if (partitions.size() == 1) {
        co_return co_await unfreeze_gently(partitions[0].mut(), s);
    } else {
        auto&& ex = std::make_exception_ptr(std::invalid_argument("Results must have at most one partition"));
        co_return coroutine::exception(std::move(ex));
    }
}

future<schema_result_value_type>
read_schema_partition_for_keyspace(distributed<service::storage_proxy>& proxy, sstring schema_table_name, sstring keyspace_name)
{
    auto schema = proxy.local().get_db().local().find_schema(NAME, schema_table_name);
    auto keyspace_key = dht::decorate_key(*schema,
        partition_key::from_singular(*schema, keyspace_name));
    auto rs = co_await db::system_keyspace::query(proxy.local().get_db(), NAME, schema_table_name, keyspace_key);
    co_return schema_result_value_type{keyspace_name, std::move(rs)};
}

future<mutation>
read_schema_partition_for_table(distributed<service::storage_proxy>& proxy, schema_ptr schema, const sstring& keyspace_name, const sstring& table_name)
{
    SCYLLA_ASSERT(schema_tables_holding_schema_mutations().contains(schema->id()));
    auto keyspace_key = partition_key::from_singular(*schema, keyspace_name);
    auto clustering_range = query::clustering_range(clustering_key_prefix::from_clustering_prefix(
            *schema, exploded_clustering_prefix({utf8_type->decompose(table_name)})));
    auto slice = partition_slice_builder(*schema)
            .with_range(std::move(clustering_range))
            .build();
    auto cmd = make_lw_shared<query::read_command>(schema->id(), schema->version(), std::move(slice), proxy.local().get_max_result_size(slice),
            query::tombstone_limit::max, query::row_limit(query::max_rows));
    co_return co_await query_partition_mutation(proxy.local(), std::move(schema), std::move(cmd), std::move(keyspace_key));
}

future<mutation>
read_keyspace_mutation(distributed<service::storage_proxy>& proxy, const sstring& keyspace_name) {
    schema_ptr s = keyspaces();
    auto key = partition_key::from_singular(*s, keyspace_name);
    auto slice = s->full_slice();
    auto cmd = make_lw_shared<query::read_command>(s->id(), s->version(), std::move(slice), proxy.local().get_max_result_size(slice), query::tombstone_limit::max);
    co_return co_await query_partition_mutation(proxy.local(), std::move(s), std::move(cmd), std::move(key));
}

mutation compact_for_schema_digest(const mutation& m) {
    // Cassandra is skipping tombstones from digest calculation
    // to avoid disagreements due to tombstone GC.
    // See https://issues.apache.org/jira/browse/CASSANDRA-6862.
    // We achieve similar effect with compact_for_compaction().
    mutation m_compacted(m);
    m_compacted.partition().compact_for_compaction_drop_tombstones_unconditionally(*m.schema(), m.decorated_key());
    return m_compacted;
}

void feed_hash_for_schema_digest(hasher& h, const mutation& m, schema_features features) {
    auto compacted = compact_for_schema_digest(m);
    if (!features.contains<schema_feature::DIGEST_INSENSITIVE_TO_EXPIRY>() || !compacted.partition().empty()) {
        feed_hash(h, compacted);
    }
}

/// Helper function which fills a given mutation with column information
/// provided the corresponding column_definition object.
static void fill_column_info(const schema& table,
                             const clustering_key& ckey,
                             const column_definition& column,
                             api::timestamp_type timestamp,
                             ttl_opt ttl,
                             mutation& m) {
    auto order = "NONE";
    if (column.is_clustering_key()) {
        order = "ASC";
    }
    auto type = column.type;
    if (type->is_reversed()) {
        type = type->underlying_type();
        if (column.is_clustering_key()) {
            order = "DESC";
        }
    }
    int32_t pos = -1;
    if (column.is_primary_key()) {
        pos = table.position(column);
    }

    m.set_clustered_cell(ckey, "column_name_bytes", data_value(column.name()), timestamp, ttl);
    m.set_clustered_cell(ckey, "kind", serialize_kind(column.kind), timestamp, ttl);
    m.set_clustered_cell(ckey, "position", pos, timestamp, ttl);
    m.set_clustered_cell(ckey, "clustering_order", sstring(order), timestamp, ttl);
    m.set_clustered_cell(ckey, "type", type->as_cql3_type().to_string(), timestamp, ttl);
}

future<> store_column_mapping(distributed<service::storage_proxy>& proxy, schema_ptr s, bool with_ttl) {
    // Skip "system*" tables -- only user-related tables are relevant
    if (static_cast<std::string_view>(s->ks_name()).starts_with(db::system_keyspace::NAME)) {
        co_return;
    }
    schema_ptr history_tbl = scylla_table_schema_history();

    // Insert the new column mapping for a given schema version (without TTL)
    std::vector<mutation> muts;
    partition_key pk = partition_key::from_exploded(*history_tbl, {uuid_type->decompose(s->id().uuid())});

    ttl_opt ttl;
    if (with_ttl) {
        ttl = gc_clock::duration(DEFAULT_GC_GRACE_SECONDS);
    }
    // Use one timestamp for all mutations for the ease of debugging
    const auto ts = api::new_timestamp();
    for (const auto& cdef : s->static_and_regular_columns()) {
        mutation m(history_tbl, pk);
        auto ckey = clustering_key::from_exploded(*history_tbl, {uuid_type->decompose(s->version().uuid()),
                                                                 utf8_type->decompose(cdef.name_as_text())});
        fill_column_info(*s, ckey, cdef, ts, ttl, m);
        muts.emplace_back(std::move(m));
    }
    co_await proxy.local().mutate_locally(std::move(muts), tracing::trace_state_ptr());
}

future<lw_shared_ptr<query::result_set>> extract_scylla_specific_keyspace_info(distributed<service::storage_proxy>& proxy, const schema_result_value_type& partition) {
    lw_shared_ptr<query::result_set> scylla_specific_rs;
    if (proxy.local().local_db().has_schema(NAME, SCYLLA_KEYSPACES)) {
        auto&& rs = partition.second;
        if (rs->empty()) {
            co_await coroutine::return_exception(std::runtime_error("query result has no rows"));
        }
        auto&& row = rs->row(0);
        auto keyspace_name = row.get_nonnull<sstring>("keyspace_name");
        auto keyspace_key = dht::decorate_key(*scylla_keyspaces(), partition_key::from_singular(*scylla_keyspaces(), keyspace_name));
        scylla_specific_rs = co_await db::system_keyspace::query(proxy.local().get_db(), NAME, SCYLLA_KEYSPACES, keyspace_key);
    }
    co_return scylla_specific_rs;
}

template<typename V>
static std::vector<V> get_list(const query::result_set_row& row, const sstring& name);

// Create types for a given keyspace. This takes care of topologically sorting user defined types.
template <typename T> static future<std::vector<user_type>> create_types(keyspace_metadata& ks, T&& range) {
    cql_type_parser::raw_builder builder(ks);
    std::unordered_set<bytes> names;
    for (const query::result_set_row& row : range) {
        auto name = row.get_nonnull<sstring>("type_name");
        names.insert(to_bytes(name));
        builder.add(std::move(name), get_list<sstring>(row, "field_names"), get_list<sstring>(row, "field_types"));
    }
    // Add user types that use any of the above types. From the
    // database point of view they haven't changed since the content
    // of system.types is the same for them. The runtime objects in
    // the other hand now point to out of date types, so we need to
    // recreate them.
    for (const auto& p : ks.user_types().get_all_types()) {
        const user_type& t = p.second;
        if (names.contains(t->_name)) {
            continue;
        }
        for (const auto& name : names) {
            if (t->references_user_type(t->_keyspace, name)) {
                std::vector<sstring> field_types;
                for (const data_type& f : t->field_types()) {
                    field_types.push_back(f->as_cql3_type().to_string());
                }
                builder.add(t->get_name_as_string(), t->string_field_names(), std::move(field_types));
            }
        }
    }
    co_return co_await builder.build();
}

future<std::vector<user_type>> create_types(replica::database& db, const std::vector<const query::result_set_row*>& rows) {
    std::vector<user_type> ret;
    for (auto i = rows.begin(), e = rows.end(); i != e;) {
        const auto &row = *i;
        auto keyspace = row->get_nonnull<sstring>("keyspace_name");
        auto next = std::find_if(i, e, [&keyspace](const query::result_set_row* r) {
            return r->get_nonnull<sstring>("keyspace_name") != keyspace;
        });
        auto ks = db.find_keyspace(keyspace).metadata();
        auto v = co_await create_types(*ks, std::ranges::subrange(i, next) | std::views::transform([] (auto&& r) -> auto& { return *r; }));
        std::ranges::move(v, std::back_inserter(ret));
        i = next;
    }
    co_return ret;
}

std::vector<data_type> read_arg_types(replica::database& db, const query::result_set_row& row, const sstring& keyspace) {
    std::vector<data_type> arg_types;
    for (const auto& arg : get_list<sstring>(row, "argument_types")) {
        arg_types.push_back(db::cql_type_parser::parse(keyspace, arg, db.user_types()));
    }
    return arg_types;
}

future<shared_ptr<cql3::functions::user_function>> create_func(replica::database& db, const query::result_set_row& row) {
    cql3::functions::function_name name{
            row.get_nonnull<sstring>("keyspace_name"), row.get_nonnull<sstring>("function_name")};
    auto arg_types = read_arg_types(db, row, name.keyspace);
    data_type return_type = db::cql_type_parser::parse(name.keyspace, row.get_nonnull<sstring>("return_type"), db.user_types());

    // FIXME: We already computed the bitcode in
    // create_function_statement, but it is not clear how to get it
    // here. In this point in the code we only get what was saved in
    // system_schema.functions, and we don't want to store the bitcode
    // If this was not the replica that the client connected to we do
    // have to produce bitcode in at least one shard. Right now this
    // gets run in each shard.

    auto arg_names = get_list<sstring>(row, "argument_names");
    auto body = row.get_nonnull<sstring>("body");
    auto language = row.get_nonnull<sstring>("language");
    auto ctx = co_await db.lang().create(language, name.name, arg_names, body);
    if (!ctx) {
        throw std::runtime_error(format("Unsupported language for UDF: {}", language));
    }
    co_return ::make_shared<cql3::functions::user_function>(std::move(name), std::move(arg_types), std::move(arg_names),
            std::move(body), language, std::move(return_type),
            row.get_nonnull<bool>("called_on_null_input"), std::move(*ctx));
}

shared_ptr<cql3::functions::user_aggregate> create_aggregate(replica::database& db, const query::result_set_row& row, const query::result_set_row* scylla_row, cql3::functions::change_batch& batch) {
    cql3::functions::function_name name{
            row.get_nonnull<sstring>("keyspace_name"), row.get_nonnull<sstring>("aggregate_name")};
    auto arg_types = read_arg_types(db, row, name.keyspace);
    data_type state_type = db::cql_type_parser::parse(name.keyspace, row.get_nonnull<sstring>("state_type"), db.user_types());
    sstring sfunc = row.get_nonnull<sstring>("state_func");
    auto ffunc = row.get<sstring>("final_func");
    auto initcond_str = row.get<sstring>("initcond");

    auto find_func = [&batch] (sstring ks, sstring name, const std::vector<data_type>& arg_types) {
        // first search current batch because aggregate may depend on functions
        // we're currently adding
        auto fname = cql3::functions::function_name{std::move(ks), std::move(name)};
        auto func = batch.find(fname, arg_types);
        if (!func) {
            func = cql3::functions::instance().find(fname, arg_types);
        }
        return func;
    };

    std::vector<data_type> acc_types{state_type};
    acc_types.insert(acc_types.end(), arg_types.begin(), arg_types.end());
    auto state_func = dynamic_pointer_cast<cql3::functions::scalar_function>(find_func(name.keyspace, sfunc, acc_types));
    if (!state_func) {
        throw std::runtime_error(format("State function {} needed by aggregate {} not found", sfunc, name.name));
    }
    if (state_func->return_type() != state_type) {
        throw std::runtime_error(format("State function {} needed by aggregate {} doesn't return state", sfunc, name.name));
    }

    ::shared_ptr<cql3::functions::scalar_function> reduce_func = nullptr;
    if (scylla_row) {
        auto rfunc_name = scylla_row->get<sstring>("reduce_func");
        auto rfunc = find_func(name.keyspace, rfunc_name.value(), {state_type, state_type});
        if (!rfunc) {
            throw std::runtime_error(format("Reduce function {} needed by aggregate {} not found", rfunc_name.value(), name.name));
        }
        reduce_func = dynamic_pointer_cast<cql3::functions::scalar_function>(rfunc);
        if (!reduce_func) {
            throw std::runtime_error(format("Reduce function {} needed by aggregate {} is not a scalar function", rfunc_name.value(), name.name));
        }
    }
    
    ::shared_ptr<cql3::functions::scalar_function> final_func = nullptr;
    if (ffunc) {
        final_func = dynamic_pointer_cast<cql3::functions::scalar_function>(
                find_func(name.keyspace, ffunc.value(), {state_type}));
        if (!final_func) {
            throw std::runtime_error(format("Final function {} needed by aggregate {} not found", ffunc.value(), name.name));
        }
    }

    bytes_opt initcond = std::nullopt;
    if (initcond_str) {
        // In general using the default dialect is wrong, but here the database is communicating with itself,
        // not the user, so any dialect should work.
        auto expr = cql3::util::do_with_parser(*initcond_str, cql3::dialect{}, std::mem_fn(&cql3_parser::CqlParser::term));
        auto dummy_ident = ::make_shared<cql3::column_identifier>("", true);
        auto column_spec = make_lw_shared<cql3::column_specification>("", "", dummy_ident, state_type);
        auto raw = cql3::expr::evaluate(prepare_expression(expr, db.as_data_dictionary(), "", nullptr, {column_spec}), cql3::query_options::DEFAULT);
        initcond = std::move(raw).to_bytes_opt();
    }
    return ::make_shared<cql3::functions::user_aggregate>(name, initcond, std::move(state_func), std::move(reduce_func), std::move(final_func));
}

template<typename... Args>
void set_cell_or_clustered(mutation& m, const clustering_key & ckey, Args && ...args) {
    m.set_clustered_cell(ckey, std::forward<Args>(args)...);
}

template<typename... Args>
void set_cell_or_clustered(mutation& m, const exploded_clustering_prefix & ckey, Args && ...args) {
    m.set_cell(ckey, std::forward<Args>(args)...);
}

template<typename Map>
static atomic_cell_or_collection
make_map_mutation(const Map& map,
                  const column_definition& column,
                  api::timestamp_type timestamp,
                  noncopyable_function<map_type_impl::native_type::value_type (const typename Map::value_type&)> f)
{
    auto column_type = static_pointer_cast<const map_type_impl>(column.type);
    auto ktyp = column_type->get_keys_type();
    auto vtyp = column_type->get_values_type();

    if (column_type->is_multi_cell()) {
        collection_mutation_description mut;

        for (auto&& entry : map) {
            auto te = f(entry);
            mut.cells.emplace_back(ktyp->decompose(data_value(te.first)), atomic_cell::make_live(*vtyp, timestamp, vtyp->decompose(data_value(te.second)), atomic_cell::collection_member::yes));
        }

        return mut.serialize(*column_type);
    } else {
        map_type_impl::native_type tmp;
        tmp.reserve(map.size());
        std::transform(map.begin(), map.end(), std::inserter(tmp, tmp.end()), std::move(f));
        return atomic_cell::make_live(*column.type, timestamp, column_type->decompose(make_map_value(column_type, std::move(tmp))));
    }
}

template<typename Map>
static atomic_cell_or_collection
make_map_mutation(const Map& map,
                  const column_definition& column,
                  api::timestamp_type timestamp)
{
    return make_map_mutation(map, column, timestamp, [](auto&& p) {
        return std::make_pair(data_value(p.first), data_value(p.second));
    });
}

template<typename K, typename Map>
static void store_map(mutation& m, const K& ckey, const bytes& name, api::timestamp_type timestamp, const Map& map) {
    auto s = m.schema();
    auto column = s->get_column_definition(name);
    SCYLLA_ASSERT(column);
    set_cell_or_clustered(m, ckey, *column, make_map_mutation(map, *column, timestamp));
}

/*
 * Keyspace metadata serialization/deserialization.
 */

std::vector<mutation> make_create_keyspace_mutations(schema_features features, lw_shared_ptr<keyspace_metadata> keyspace, api::timestamp_type timestamp, bool with_tables_and_types_and_functions)
{
    std::vector<mutation> mutations;
    schema_ptr s = keyspaces();
    auto pkey = partition_key::from_singular(*s, keyspace->name());
    mutation m(s, pkey);
    auto ckey = clustering_key_prefix::make_empty();
    m.set_cell(ckey, "durable_writes", keyspace->durable_writes(), timestamp);

    auto map = keyspace->strategy_options();
    map["class"] = keyspace->strategy_name();
    store_map(m, ckey, "replication", timestamp, map);

    if (features.contains<schema_feature::SCYLLA_KEYSPACES>()) {
        schema_ptr scylla_keyspaces_s = scylla_keyspaces();
        mutation scylla_m(scylla_keyspaces_s, pkey); // pkey can be reused, it's identical in both tables
        auto& storage_options = keyspace->get_storage_options();
        sstring storage_type(storage_options.type_string());
        auto storage_map = storage_options.to_map();
        if (!storage_map.empty()) {
            scylla_m.set_cell(ckey, "storage_type", storage_type, timestamp);
            store_map(scylla_m, ckey, "storage_options", timestamp, storage_map);
        }
        auto initial_tablets = keyspace->initial_tablets();
        if (initial_tablets.has_value()) {
            scylla_m.set_cell(ckey, "initial_tablets", int32_t(*initial_tablets), timestamp);
        }
        mutations.emplace_back(std::move(scylla_m));
    }

    mutations.emplace_back(std::move(m));

    if (with_tables_and_types_and_functions) {
        for (const auto& kv : keyspace->user_types().get_all_types()) {
            add_type_to_schema_mutation(kv.second, timestamp, mutations);
        }
        for (auto&& s : keyspace->cf_meta_data() | std::views::values) {
            add_table_or_view_to_schema_mutation(s, timestamp, true, mutations);
        }
    }
    return mutations;
}

std::vector<mutation> make_drop_keyspace_mutations(schema_features features, lw_shared_ptr<keyspace_metadata> keyspace, api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    for (auto&& schema_table : all_tables(schema_features::full())) {
        auto pkey = partition_key::from_exploded(*schema_table, {utf8_type->decompose(keyspace->name())});
        mutation m{schema_table, pkey};
        m.partition().apply(tombstone{timestamp, gc_clock::now()});
        mutations.emplace_back(std::move(m));
    }
    if (features.contains<schema_feature::SCYLLA_KEYSPACES>()) {
        auto pkey = partition_key::from_exploded(*scylla_keyspaces(), {utf8_type->decompose(keyspace->name())});
        mutation km{scylla_keyspaces(), pkey};
        km.partition().apply(tombstone{timestamp, gc_clock::now()});
        mutations.emplace_back(std::move(km));
    }
    return mutations;
}

/**
 * Deserialize only Keyspace attributes without nested tables or types
 *
 * @param partition Keyspace attributes in serialized form
 */
future<lw_shared_ptr<keyspace_metadata>> create_keyspace_from_schema_partition(distributed<service::storage_proxy>& proxy,
                                                                               const schema_result_value_type& result,
                                                                               lw_shared_ptr<query::result_set> scylla_specific_rs)
{
    auto&& rs = result.second;
    if (rs->empty()) {
        throw std::runtime_error("query result has no rows");
    }
    auto&& row = rs->row(0);
    auto keyspace_name = row.get_nonnull<sstring>("keyspace_name");
    // We get called from multiple shards with result set originating on only one of them.
    // Cannot use copying accessors for "deep" types like map, because we will hit shared_ptr asserts
    // (or screw up shared pointers)
    const auto& replication = row.get_nonnull<map_type_impl::native_type>("replication");

    std::map<sstring, sstring> strategy_options;
    for (auto& p : replication) {
        strategy_options.emplace(value_cast<sstring>(p.first), value_cast<sstring>(p.second));
    }
    auto strategy_name = strategy_options["class"];
    strategy_options.erase("class");
    bool durable_writes = row.get_nonnull<bool>("durable_writes");

    data_dictionary::storage_options storage_opts;
    std::optional<unsigned> initial_tablets;
    // Scylla-specific row will only be present if SCYLLA_KEYSPACES schema feature is available in the cluster
    if (scylla_specific_rs) {
        if (!scylla_specific_rs->empty()) {
            const auto& row = scylla_specific_rs->row(0);
            auto storage_type = row.get<sstring>("storage_type");
            auto options = row.get<map_type_impl::native_type>("storage_options");
            if (storage_type && options) {
                std::map<sstring, sstring> values;
                for (const auto& entry : *options) {
                    values.emplace(value_cast<sstring>(entry.first), value_cast<sstring>(entry.second));
                }
                storage_opts.value = data_dictionary::storage_options::from_map(std::string_view(*storage_type), values);
            }
            initial_tablets = row.get<int>("initial_tablets");
        }
    }
    co_return keyspace_metadata::new_keyspace(keyspace_name, strategy_name, strategy_options, initial_tablets, durable_writes, storage_opts);
}

template<typename V>
static std::vector<V> get_list(const query::result_set_row& row, const sstring& name) {
    std::vector<V> list;

    const auto& values = row.get_nonnull<const list_type_impl::native_type&>(name);
    for (auto&& v : values) {
        list.emplace_back(value_cast<V>(v));
    };

    return list;
}

future<std::vector<user_type>> create_types_from_schema_partition(
        keyspace_metadata& ks, lw_shared_ptr<query::result_set> result) {
    co_return co_await create_types(ks, result->rows());
}

seastar::future<std::vector<shared_ptr<cql3::functions::user_function>>> create_functions_from_schema_partition(
        replica::database& db, lw_shared_ptr<query::result_set> result) {
    std::vector<shared_ptr<cql3::functions::user_function>> ret;
    for (const auto& row : result->rows()) {
        ret.emplace_back(co_await create_func(db, row));
    }
    co_return ret;
}

std::vector<shared_ptr<cql3::functions::user_aggregate>> create_aggregates_from_schema_partition(
        replica::database& db, lw_shared_ptr<query::result_set> result, lw_shared_ptr<query::result_set> scylla_result, cql3::functions::change_batch& batch) {
    std::unordered_multimap<sstring, const query::result_set_row*> scylla_aggs;
    if (scylla_result) {
        for (const auto& scylla_row : scylla_result->rows()) {
            auto scylla_agg_name = scylla_row.get_nonnull<sstring>("aggregate_name");
            scylla_aggs.emplace(scylla_agg_name, &scylla_row);
        }
    }

    std::vector<shared_ptr<cql3::functions::user_aggregate>> ret;
    for (const auto& row : result->rows()) {
        auto agg_name = row.get_nonnull<sstring>("aggregate_name");
        auto agg_args = read_arg_types(db, row, row.get_nonnull<sstring>("keyspace_name"));
        const query::result_set_row *scylla_row_ptr = nullptr;
        for (auto [it, end] = scylla_aggs.equal_range(agg_name); it != end; ++it) {
            auto scylla_agg_args = read_arg_types(db, *it->second, it->second->get_nonnull<sstring>("keyspace_name"));
            if (agg_args == scylla_agg_args) {
                scylla_row_ptr = it->second;
                break;
            }
        }
        ret.emplace_back(create_aggregate(db, row, scylla_row_ptr, batch));
    }
    return ret;
}

/*
 * User type metadata serialization/deserialization
 */

template<typename Func, typename T, typename... Args>
static atomic_cell_or_collection
make_list_mutation(const std::vector<T, Args...>& values,
                const column_definition& column,
                api::timestamp_type timestamp,
                Func&& f)
{
    auto column_type = static_pointer_cast<const list_type_impl>(column.type);
    auto vtyp = column_type->get_elements_type();

    if (column_type->is_multi_cell()) {
        collection_mutation_description m;
        m.cells.reserve(values.size());
        m.tomb.timestamp = timestamp - 1;
        m.tomb.deletion_time = gc_clock::now();

        for (auto&& value : values) {
            auto dv = f(value);
            auto uuid = utils::UUID_gen::get_time_UUID_bytes();
            m.cells.emplace_back(
                bytes(reinterpret_cast<const int8_t*>(uuid.data()), uuid.size()),
                atomic_cell::make_live(*vtyp, timestamp, vtyp->decompose(std::move(dv)), atomic_cell::collection_member::yes));
        }

        return m.serialize(*column_type);
    } else {
        list_type_impl::native_type tmp;
        tmp.reserve(values.size());
        std::transform(values.begin(), values.end(), std::back_inserter(tmp), f);
        return atomic_cell::make_live(*column.type, timestamp, column_type->decompose(make_list_value(column_type, std::move(tmp))));
    }
}

void add_type_to_schema_mutation(user_type type, api::timestamp_type timestamp, std::vector<mutation>& mutations)
{
    schema_ptr s = types();
    auto pkey = partition_key::from_singular(*s, type->_keyspace);
    auto ckey = clustering_key::from_singular(*s, type->get_name_as_string());
    mutation m{s, pkey};

    auto field_names_column = s->get_column_definition("field_names");
    auto field_names = make_list_mutation(type->field_names(), *field_names_column, timestamp, [](auto&& name) {
        return utf8_type->deserialize(name);
    });
    m.set_clustered_cell(ckey, *field_names_column, std::move(field_names));

    auto field_types_column = s->get_column_definition("field_types");
    auto field_types = make_list_mutation(type->field_types(), *field_types_column, timestamp, [](auto&& type) {
        return data_value(type->as_cql3_type().to_string());
    });
    m.set_clustered_cell(ckey, *field_types_column, std::move(field_types));

    mutations.emplace_back(std::move(m));
}

std::vector<mutation> make_create_type_mutations(lw_shared_ptr<keyspace_metadata> keyspace, user_type type, api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    add_type_to_schema_mutation(type, timestamp, mutations);
    return mutations;
}

std::vector<mutation> make_drop_type_mutations(lw_shared_ptr<keyspace_metadata> keyspace, user_type type, api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    schema_ptr s = types();
    auto pkey = partition_key::from_singular(*s, type->_keyspace);
    auto ckey = clustering_key::from_singular(*s, type->get_name_as_string());
    mutation m{s, pkey};
    m.partition().apply_delete(*s, ckey, tombstone(timestamp, gc_clock::now()));
    mutations.emplace_back(std::move(m));

    return mutations;
}

/*
 * UDF metadata serialization/deserialization.
 */

static std::pair<mutation, clustering_key> get_mutation(schema_ptr s, const cql3::functions::function& func) {
    auto name = func.name();
    auto pkey = partition_key::from_singular(*s, name.keyspace);

    list_type_impl::native_type arg_types;
    for (const auto& arg_type : func.arg_types()) {
        arg_types.emplace_back(arg_type->as_cql3_type().to_string());
    }
    auto arg_list_type = list_type_impl::get_instance(utf8_type, false);
    data_value arg_types_val = make_list_value(arg_list_type, std::move(arg_types));
    auto ckey = clustering_key::from_exploded(
            *s, {utf8_type->decompose(name.name), arg_list_type->decompose(arg_types_val)});
    mutation m{s, pkey};
    return {std::move(m), std::move(ckey)};
}

std::vector<mutation> make_create_function_mutations(shared_ptr<cql3::functions::user_function> func,
        api::timestamp_type timestamp) {
    schema_ptr s = functions();
    auto p = get_mutation(s, *func);
    mutation& m = p.first;
    clustering_key& ckey = p.second;
    auto argument_names_column = s->get_column_definition("argument_names");
    auto argument_names = make_list_mutation(func->arg_names(), *argument_names_column, timestamp, [] (auto&& name) {
        return name;
    });
    m.set_clustered_cell(ckey, *argument_names_column, std::move(argument_names));
    m.set_clustered_cell(ckey, "body", func->body(), timestamp);
    m.set_clustered_cell(ckey, "language", func->language(), timestamp);
    m.set_clustered_cell(ckey, "return_type", func->return_type()->as_cql3_type().to_string(), timestamp);
    m.set_clustered_cell(ckey, "called_on_null_input", func->called_on_null_input(), timestamp);
    return make_mutation_vector(std::move(m));
}

std::vector<mutation> make_drop_function_mutations(schema_ptr s, const cql3::functions::function& func, api::timestamp_type timestamp) {
    auto p = get_mutation(s, func);
    mutation& m = p.first;
    clustering_key& ckey = p.second;
    m.partition().apply_delete(*s, ckey, tombstone(timestamp, gc_clock::now()));
    return make_mutation_vector(std::move(m));
}

std::vector<mutation> make_drop_function_mutations(shared_ptr<cql3::functions::user_function> func, api::timestamp_type timestamp) {
    return make_drop_function_mutations(functions(), *func, timestamp);
}

/*
 * UDA metadata serialization/deserialization
 */

static std::pair<mutation, clustering_key> get_mutation(schema_ptr s, const cql3::functions::user_aggregate& aggregate) {
    auto name = aggregate.name();
    auto pkey = partition_key::from_singular(*s, name.keyspace);

    list_type_impl::native_type arg_types;
    for (const auto& arg_type : aggregate.arg_types()) {
        arg_types.emplace_back(arg_type->as_cql3_type().to_string());
    }
    auto arg_list_type = list_type_impl::get_instance(utf8_type, false);
    data_value arg_types_val = make_list_value(arg_list_type, std::move(arg_types));
    auto ckey = clustering_key::from_exploded(
            *s, {utf8_type->decompose(name.name), arg_list_type->decompose(arg_types_val)});
    mutation m{s, pkey};
    return {std::move(m), std::move(ckey)};
}

std::vector<mutation> make_create_aggregate_mutations(schema_features features, shared_ptr<cql3::functions::user_aggregate> aggregate, api::timestamp_type timestamp) {
    schema_ptr s = aggregates();
    auto p = get_mutation(s, *aggregate);
    mutation& m = p.first;
    clustering_key& ckey = p.second;
    std::vector<mutation> muts;

    data_type state_type = aggregate->sfunc()->arg_types()[0];
    if (aggregate->has_finalfunc()) {
        m.set_clustered_cell(ckey, "final_func", aggregate->finalfunc()->name().name, timestamp);
    }
    if (aggregate->initcond()) {
        m.set_clustered_cell(ckey, "initcond", state_type->deserialize(*aggregate->initcond()).to_parsable_string(), timestamp);
    }
    m.set_clustered_cell(ckey, "return_type", aggregate->return_type()->as_cql3_type().to_string(), timestamp);
    m.set_clustered_cell(ckey, "state_func", aggregate->sfunc()->name().name, timestamp);
    m.set_clustered_cell(ckey, "state_type", state_type->as_cql3_type().to_string(), timestamp);
    muts.emplace_back(std::move(m));

    if (features.contains<schema_feature::SCYLLA_AGGREGATES>() && aggregate->is_reducible()) {
        schema_ptr sa_schema = scylla_aggregates();
        auto sa_p = get_mutation(sa_schema, *aggregate);
        mutation& sa_mut = sa_p.first;
        clustering_key& sa_ckey = sa_p.second;
        sa_mut.set_clustered_cell(sa_ckey, "reduce_func", aggregate->reducefunc()->name().name, timestamp);
        sa_mut.set_clustered_cell(sa_ckey, "state_type", state_type->as_cql3_type().to_string(), timestamp);

        muts.emplace_back(std::move(sa_mut));
    }

    return muts;
}

std::vector<mutation> make_drop_aggregate_mutations(schema_features features, shared_ptr<cql3::functions::user_aggregate> aggregate, api::timestamp_type timestamp) {
    auto muts = make_drop_function_mutations(aggregates(), *aggregate, timestamp);
    if (features.contains<schema_feature::SCYLLA_AGGREGATES>() && aggregate->is_reducible()) {
        auto scylla_muts = make_drop_function_mutations(scylla_aggregates(), *aggregate, timestamp);
        std::move(scylla_muts.begin(), scylla_muts.end(), std::back_inserter(muts));
    }

    return muts;
}

/*
 * Table metadata serialization/deserialization.
 */

/// Returns mutations which when applied to the database will cause all schema changes
/// which create or alter the table with a given name, made with timestamps smaller than t,
/// have no effect. Used when overriding schema to shadow concurrent conflicting schema changes.
/// Shouldn't be needed if schema changes are serialized with RAFT.
static schema_mutations make_table_deleting_mutations(const sstring& ks, const sstring& table, bool is_view, api::timestamp_type t) {
    tombstone tomb;

    // Generate neutral mutations if t == api::min_timestamp
    if (t > api::min_timestamp) {
        tomb = tombstone(t - 1, gc_clock::now());
    }

    auto tables_m_s = is_view ? views() : tables();
    mutation tables_m{tables_m_s, partition_key::from_singular(*tables_m_s, ks)};
    {
        auto ckey = clustering_key::from_singular(*tables_m_s, table);
        tables_m.partition().apply_delete(*tables_m_s, ckey, tomb);
    }

    mutation scylla_tables_m{scylla_tables(), partition_key::from_singular(*scylla_tables(), ks)};
    {
        auto ckey = clustering_key::from_singular(*scylla_tables(), table);
        scylla_tables_m.partition().apply_delete(*scylla_tables(), ckey, tomb);
    }

    auto make_drop_columns = [&] (const schema_ptr& s) {
        mutation m{s, partition_key::from_singular(*s, ks)};
        auto ckey = clustering_key::from_exploded(*s, {utf8_type->decompose(table)});
        m.partition().apply_delete(*s, ckey, tomb);
        return m;
    };

    return schema_mutations(std::move(tables_m),
                            make_drop_columns(columns()),
                            make_drop_columns(view_virtual_columns()),
                            make_drop_columns(computed_columns()),
                            mutation(indexes(), partition_key::from_singular(*indexes(), ks)),
                            make_drop_columns(dropped_columns()),
                            std::move(scylla_tables_m)
    );
}

std::vector<mutation> make_create_table_mutations(schema_ptr table, api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    add_table_or_view_to_schema_mutation(table, timestamp, true, mutations);
    make_table_deleting_mutations(table->ks_name(), table->cf_name(), table->is_view(), timestamp)
        .copy_to(mutations);
    return mutations;
}

static void add_table_params_to_mutations(mutation& m, const clustering_key& ckey, schema_ptr table, api::timestamp_type timestamp) {
    m.set_clustered_cell(ckey, "bloom_filter_fp_chance", table->bloom_filter_fp_chance(), timestamp);
    m.set_clustered_cell(ckey, "comment", table->comment(), timestamp);
    m.set_clustered_cell(ckey, "default_time_to_live", gc_clock::as_int32(table->default_time_to_live()), timestamp);
    m.set_clustered_cell(ckey, "gc_grace_seconds", gc_clock::as_int32(table->gc_grace_seconds()), timestamp);
    m.set_clustered_cell(ckey, "max_index_interval", table->max_index_interval(), timestamp);
    m.set_clustered_cell(ckey, "memtable_flush_period_in_ms", table->memtable_flush_period(), timestamp);
    m.set_clustered_cell(ckey, "min_index_interval", table->min_index_interval(), timestamp);
    m.set_clustered_cell(ckey, "speculative_retry", table->speculative_retry().to_sstring(), timestamp);
    m.set_clustered_cell(ckey, "crc_check_chance", table->crc_check_chance(), timestamp);

    store_map(m, ckey, "caching", timestamp, table->caching_options().to_map());

    {
        auto map = table->compaction_strategy_options();
        map["class"] = sstables::compaction_strategy::name(table->configured_compaction_strategy());
        store_map(m, ckey, "compaction", timestamp, map);
    }

    store_map(m, ckey, "compression", timestamp, table->get_compressor_params().get_options());

    std::map<sstring, bytes> map;

    if (!table->extensions().empty()) {
        for (auto& p : table->extensions()) {
            map.emplace(p.first, p.second->serialize());
        }
    }

    store_map(m, ckey, "extensions", timestamp, map);
}

static data_type expand_user_type(data_type);

static std::vector<data_type> expand_user_types(const std::vector<data_type>& types) {
    std::vector<data_type> result;
    result.reserve(types.size());
    std::transform(types.begin(), types.end(), std::back_inserter(result), &expand_user_type);
    return result;
}

static data_type expand_user_type(data_type original) {
    if (original->is_user_type()) {
        return tuple_type_impl::get_instance(
                        expand_user_types(
                                        static_pointer_cast<const user_type_impl>(
                                                        original)->field_types()));
    }
    if (original->is_tuple()) {
        return tuple_type_impl::get_instance(
                        expand_user_types(
                                        static_pointer_cast<
                                                        const tuple_type_impl>(
                                                        original)->all_types()));
    }
    if (original->is_reversed()) {
        return reversed_type_impl::get_instance(
                        expand_user_type(original->underlying_type()));
    }

    if (original->is_collection()) {

        auto ct = static_pointer_cast<const collection_type_impl>(original);

        if (ct->is_list()) {
            return list_type_impl::get_instance(
                            expand_user_type(ct->value_comparator()),
                            ct->is_multi_cell());
        }
        if (ct->is_map()) {
            return map_type_impl::get_instance(
                            expand_user_type(ct->name_comparator()),
                            expand_user_type(ct->value_comparator()),
                            ct->is_multi_cell());
        }
        if (ct->is_set()) {
            return set_type_impl::get_instance(
                            expand_user_type(ct->name_comparator()),
                            ct->is_multi_cell());
        }
    }

    return original;
}

static void add_dropped_column_to_schema_mutation(schema_ptr table, const sstring& name, const schema::dropped_column& column, api::timestamp_type timestamp, mutation& m) {
    auto ckey = clustering_key::from_exploded(*dropped_columns(), {utf8_type->decompose(table->cf_name()), utf8_type->decompose(name)});
    db_clock::time_point tp(db_clock::duration(column.timestamp));
    m.set_clustered_cell(ckey, "dropped_time", tp, timestamp);

    /*
     * From origin:
     * we never store actual UDT names in dropped column types (so that we can safely drop types if nothing refers to
     * them anymore), so before storing dropped columns in schema we expand UDTs to tuples. See expandUserTypes method.
     * Because of that, we can safely pass Types.none() to parse()
     */
    m.set_clustered_cell(ckey, "type", expand_user_type(column.type)->as_cql3_type().to_string(), timestamp);
}

mutation make_scylla_tables_mutation(schema_ptr table, api::timestamp_type timestamp) {
    schema_ptr s = tables();
    auto pkey = partition_key::from_singular(*s, table->ks_name());
    auto ckey = clustering_key::from_singular(*s, table->cf_name());
    mutation m(scylla_tables(), pkey);
    m.set_clustered_cell(ckey, "version", table->version().uuid(), timestamp);
    // Since 4.0, we stopped using cdc column in scylla tables. Extensions are
    // used instead. Since we stopped reading this column in commit 861c7b5, we
    // can now keep it always empty.
    auto& cdc_cdef = *scylla_tables()->get_column_definition("cdc");
    m.set_clustered_cell(ckey, cdc_cdef, atomic_cell::make_dead(timestamp, gc_clock::now()));
    if (table->has_custom_partitioner()) {
        m.set_clustered_cell(ckey, "partitioner", table->get_partitioner().name(), timestamp);
    } else {
        // Avoid storing anything for default partitioner, so we don't end up with
        // different digests on different nodes due to the other node redacting
        // the partitioner column when the per_table_partitioners cluster feature is disabled.
        //
        // Tombstones are not considered for schema digest, so this is okay (and
        // needed in order for disabling of per_table_partitioners to have effect).
        auto& cdef = *scylla_tables()->get_column_definition("partitioner");
        m.set_clustered_cell(ckey, cdef, atomic_cell::make_dead(timestamp, gc_clock::now()));
    }
    // A table will have engaged tablet options
    // only after they were set by CREATE TABLE or ALTER TABLE,
    // Meaning the cluster feature is enabled, so it is safe to write
    // to this columns.
    if (table->has_tablet_options()) {
        auto& map = table->raw_tablet_options();
        auto& cdef = *scylla_tables()->get_column_definition("tablets");
        if (map.empty()) {
            m.set_clustered_cell(ckey, cdef, atomic_cell::make_dead(timestamp, gc_clock::now()));
        } else {
            m.set_clustered_cell(ckey, cdef, make_map_mutation(map, cdef, timestamp));
        }
    }
    // In-memory tables are deprecated since scylla-2024.1.0
    // FIXME: delete the column when there's no live version supporting it anymore.
    // Writing it here breaks upgrade rollback to versions that do not support the in_memory schema_feature
    return m;
}

static schema_mutations make_table_mutations(schema_ptr table, api::timestamp_type timestamp, bool with_columns_and_triggers)
{
    // When adding new schema properties, don't set cells for default values so that
    // both old and new nodes will see the same version during rolling upgrades.

    // For property that can be null (and can be changed), we insert tombstones, to make sure
    // we don't keep a property the user has removed
    schema_ptr s = tables();
    auto pkey = partition_key::from_singular(*s, table->ks_name());
    mutation m{s, pkey};
    auto ckey = clustering_key::from_singular(*s, table->cf_name());
    m.set_clustered_cell(ckey, "id", table->id().uuid(), timestamp);

    auto scylla_tables_mutation = make_scylla_tables_mutation(table, timestamp);

    list_type_impl::native_type flags;
    if (table->is_super()) {
        flags.emplace_back("super");
    }
    if (table->is_dense()) {
        flags.emplace_back("dense");
    }
    if (table->is_compound()) {
        flags.emplace_back("compound");
    }
    if (table->is_counter()) {
        flags.emplace_back("counter");
    }

    m.set_clustered_cell(ckey, "flags", make_list_value(s->get_column_definition("flags")->type, flags), timestamp);

    add_table_params_to_mutations(m, ckey, table, timestamp);

    mutation columns_mutation(columns(), pkey);
    mutation computed_columns_mutation(computed_columns(), pkey);
    mutation dropped_columns_mutation(dropped_columns(), pkey);
    mutation indices_mutation(indexes(), pkey);

    if (with_columns_and_triggers) {
        for (auto&& column : table->v3().all_columns()) {
            if (column.is_view_virtual()) {
                throw std::logic_error("view_virtual column found in non-view table");
            }
            add_column_to_schema_mutation(table, column, timestamp, columns_mutation);
            if (column.is_computed()) {
                add_computed_column_to_schema_mutation(table, column, timestamp, computed_columns_mutation);
            }
        }
        for (auto&& index : table->indices()) {
            add_index_to_schema_mutation(table, index, timestamp, indices_mutation);
        }
        // TODO: triggers

        for (auto&& e : table->dropped_columns()) {
            add_dropped_column_to_schema_mutation(table, e.first, e.second, timestamp, dropped_columns_mutation);
        }
    }

    return schema_mutations{std::move(m),
                            std::move(columns_mutation),
                            std::nullopt,
                            std::move(computed_columns_mutation),
                            std::move(indices_mutation),
                            std::move(dropped_columns_mutation),
                            std::move(scylla_tables_mutation)};
}

void add_table_or_view_to_schema_mutation(schema_ptr s, api::timestamp_type timestamp, bool with_columns, std::vector<mutation>& mutations)
{
    make_schema_mutations(s, timestamp, with_columns).copy_to(mutations);
}

static schema_mutations make_view_mutations(view_ptr view, api::timestamp_type timestamp, bool with_columns);
static void make_drop_table_or_view_mutations(schema_ptr schema_table, schema_ptr table_or_view, api::timestamp_type timestamp, std::vector<mutation>& mutations);

static void make_update_indices_mutations(
        replica::database& db,
        schema_ptr old_table,
        schema_ptr new_table,
        api::timestamp_type timestamp,
        std::vector<mutation>& mutations)
{
    mutation indices_mutation(indexes(), partition_key::from_singular(*indexes(), old_table->ks_name()));

    auto diff = difference(old_table->all_indices(), new_table->all_indices());

    // indices that are no longer needed
    for (auto&& name : diff.entries_only_on_left) {
        const index_metadata& index = old_table->all_indices().at(name);
        drop_index_from_schema_mutation(old_table, index, timestamp, mutations);
        schema_ptr view;
        try {
            view = db.find_schema(old_table->ks_name(), secondary_index::index_table_name(name));
            db.get_notifier().before_drop_column_family(*view, mutations, timestamp);
        } catch (const replica::no_such_column_family&) {
            on_internal_error(slogger, format("Could not find schema for dropped index {}.{}",
                    old_table->ks_name(), secondary_index::index_table_name(name)));
        }
        make_drop_table_or_view_mutations(views(), view, timestamp, mutations);
    }

    auto add_index = [&](const sstring& name) -> view_ptr {
        const index_metadata& index = new_table->all_indices().at(name);
        add_index_to_schema_mutation(new_table, index, timestamp, indices_mutation);
        auto& cf = db.find_column_family(new_table);
        auto view = cf.get_index_manager().create_view_for_index(index);
        auto view_mutations = make_view_mutations(view, timestamp, true);
        view_mutations.copy_to(mutations);
        return view;
    };

    // old indices with updated attributes
    for (auto&& name : diff.entries_differing) {
        add_index(name);
    }
    // Newly added indices. Because these are newly created tables (views),
    // we need to call the before_create_column_family callback for them.
    // If we don't, among other things *tablets* will not be created for
    // these new views.
    // The callbacks must be called in a Seastar thread, which means that
    // *this* function must be called in a Seastar thread when creating an
    // index.
    for (auto&& name : diff.entries_only_on_right) {
        auto view = add_index(name);
        auto ksm = db.find_keyspace(new_table->ks_name()).metadata();
        db.get_notifier().before_create_column_family(*ksm, *view, mutations, timestamp);
    }

    mutations.emplace_back(std::move(indices_mutation));
}

static void add_drop_column_to_mutations(schema_ptr table, const sstring& name, const schema::dropped_column& dc, api::timestamp_type timestamp, std::vector<mutation>& mutations) {
    schema_ptr s = dropped_columns();
    auto pkey = partition_key::from_singular(*s, table->ks_name());
    auto ckey = clustering_key::from_exploded(*s, {utf8_type->decompose(table->cf_name()), utf8_type->decompose(name)});
    mutation m(s, pkey);
    add_dropped_column_to_schema_mutation(table, name, dc, timestamp, m);
    mutations.emplace_back(std::move(m));
}

static void make_update_columns_mutations(schema_ptr old_table,
        schema_ptr new_table,
        api::timestamp_type timestamp,
        std::vector<mutation>& mutations) {
    mutation columns_mutation(columns(), partition_key::from_singular(*columns(), old_table->ks_name()));
    mutation view_virtual_columns_mutation(view_virtual_columns(), partition_key::from_singular(*columns(), old_table->ks_name()));
    mutation computed_columns_mutation(computed_columns(), partition_key::from_singular(*columns(), old_table->ks_name()));

    auto diff = difference(old_table->v3().columns_by_name(), new_table->v3().columns_by_name());

    // columns that are no longer needed
    for (auto&& name : diff.entries_only_on_left) {
        // Thrift only knows about the REGULAR ColumnDefinition type, so don't consider other type
        // are being deleted just because they are not here.
        const column_definition& column = *old_table->v3().columns_by_name().at(name);
        if (column.is_view_virtual()) {
            drop_column_from_schema_mutation(view_virtual_columns(), old_table, column.name_as_text(), timestamp, mutations);
        } else {
            drop_column_from_schema_mutation(columns(), old_table, column.name_as_text(), timestamp, mutations);
        }
        if (column.is_computed()) {
            drop_column_from_schema_mutation(computed_columns(), old_table, column.name_as_text(), timestamp, mutations);
        }
    }

    // newly added columns and old columns with updated attributes
    for (auto&& name : boost::range::join(diff.entries_differing, diff.entries_only_on_right)) {
        const column_definition& column = *new_table->v3().columns_by_name().at(name);
        if (column.is_view_virtual()) {
            add_column_to_schema_mutation(new_table, column, timestamp, view_virtual_columns_mutation);
        } else {
            add_column_to_schema_mutation(new_table, column, timestamp, columns_mutation);
        }
        if (column.is_computed()) {
            add_computed_column_to_schema_mutation(new_table, column, timestamp, computed_columns_mutation);
        }
    }

    mutations.emplace_back(std::move(columns_mutation));
    mutations.emplace_back(std::move(view_virtual_columns_mutation));
    mutations.emplace_back(std::move(computed_columns_mutation));

    // dropped columns
    auto dc_diff = difference(old_table->dropped_columns(), new_table->dropped_columns());

    // newly dropped columns
    // columns added then dropped again
    for (auto& name : boost::range::join(dc_diff.entries_differing, dc_diff.entries_only_on_right)) {
        add_drop_column_to_mutations(new_table, name, new_table->dropped_columns().at(name), timestamp, mutations);
    }
}

std::vector<mutation> make_update_table_mutations(replica::database& db,
    lw_shared_ptr<keyspace_metadata> keyspace,
    schema_ptr old_table,
    schema_ptr new_table,
    api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    add_table_or_view_to_schema_mutation(new_table, timestamp, false, mutations);
    make_update_indices_mutations(db, old_table, new_table, timestamp, mutations);
    make_update_columns_mutations(std::move(old_table), std::move(new_table), timestamp, mutations);

    warn(unimplemented::cause::TRIGGERS);
    return mutations;
}

static void make_drop_table_or_view_mutations(schema_ptr schema_table,
            schema_ptr table_or_view,
            api::timestamp_type timestamp,
            std::vector<mutation>& mutations) {
    auto pkey = partition_key::from_singular(*schema_table, table_or_view->ks_name());
    mutation m{schema_table, pkey};
    auto ckey = clustering_key::from_singular(*schema_table, table_or_view->cf_name());
    m.partition().apply_delete(*schema_table, ckey, tombstone(timestamp, gc_clock::now()));
    mutations.emplace_back(m);
    for (auto& column : table_or_view->v3().all_columns()) {
        if (column.is_view_virtual()) {
            drop_column_from_schema_mutation(view_virtual_columns(), table_or_view, column.name_as_text(), timestamp, mutations);
        } else {
            drop_column_from_schema_mutation(columns(), table_or_view, column.name_as_text(), timestamp, mutations);
        }
        if (column.is_computed()) {
            drop_column_from_schema_mutation(computed_columns(), table_or_view, column.name_as_text(), timestamp, mutations);
        }
    }
    for (auto& column : table_or_view->dropped_columns() | std::views::keys) {
        drop_column_from_schema_mutation(dropped_columns(), table_or_view, column, timestamp, mutations);
    }
    mutation m1{scylla_tables(), pkey};
    m1.partition().apply_delete(*scylla_tables(), ckey, tombstone(timestamp, gc_clock::now()));
    mutations.emplace_back(m1);
}

std::vector<mutation> make_drop_table_mutations(lw_shared_ptr<keyspace_metadata> keyspace, schema_ptr table, api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    make_drop_table_or_view_mutations(tables(), std::move(table), timestamp, mutations);

    return mutations;
}

future<schema_mutations> read_table_mutations(distributed<service::storage_proxy>& proxy, const qualified_name& table, schema_ptr s)
{
    auto&& [cf_m, col_m, vv_col_m, c_col_m, dropped_m, idx_m, st_m] = co_await coroutine::all(
        [&] { return read_schema_partition_for_table(proxy, s, table.keyspace_name, table.table_name); },
        [&] { return read_schema_partition_for_table(proxy, columns(), table.keyspace_name, table.table_name); },
        [&] { return read_schema_partition_for_table(proxy, view_virtual_columns(), table.keyspace_name, table.table_name); },
        [&] { return read_schema_partition_for_table(proxy, computed_columns(), table.keyspace_name, table.table_name); },
        [&] { return read_schema_partition_for_table(proxy, dropped_columns(), table.keyspace_name, table.table_name); },
        [&] { return read_schema_partition_for_table(proxy, indexes(), table.keyspace_name, table.table_name); },
        [&] { return read_schema_partition_for_table(proxy, scylla_tables(), table.keyspace_name, table.table_name); }
    );
    co_return schema_mutations{std::move(cf_m), std::move(col_m), std::move(vv_col_m), std::move(c_col_m), std::move(idx_m), std::move(dropped_m), std::move(st_m)};
}

future<schema_ptr> create_table_from_name(distributed<service::storage_proxy>& proxy, const sstring& keyspace, const sstring& table)
{
    auto qn = qualified_name(keyspace, table);
    auto sm = co_await read_table_mutations(proxy, qn, tables());
    if (!sm.live()) {
        co_await coroutine::return_exception(std::runtime_error(format("{}:{} not found in the schema definitions keyspace.", qn.keyspace_name, qn.table_name)));
    }
    co_return create_table_from_mutations(proxy, std::move(sm));
}

// Limit concurrency of user tables to prevent stalls.
// See https://github.com/scylladb/scylladb/issues/11574
// Note: we aim at providing enough concurrency to utilize
// the cpu while operations are blocked on disk I/O
// and or filesystem calls, e.g. fsync.
constexpr size_t max_concurrent = 8;

/**
 * Deserialize tables from low-level schema representation, all of them belong to the same keyspace
 *
 * @return map containing name of the table and its metadata for faster lookup
 */
future<std::map<sstring, schema_ptr>> create_tables_from_tables_partition(distributed<service::storage_proxy>& proxy, const schema_result::mapped_type& result)
{
    auto tables = std::map<sstring, schema_ptr>();
    co_await max_concurrent_for_each(result->rows().begin(), result->rows().end(), max_concurrent, [&] (const query::result_set_row& row) -> future<> {
        schema_ptr cfm = co_await create_table_from_table_row(proxy, row);
        tables.emplace(cfm->cf_name(), std::move(cfm));
    });
    co_return std::move(tables);
}

/**
 * Deserialize table metadata from low-level representation
 *
 * @return Metadata deserialized from schema
 */
static future<schema_ptr> create_table_from_table_row(distributed<service::storage_proxy>& proxy, const query::result_set_row& row)
{
    auto ks_name = row.get_nonnull<sstring>("keyspace_name");
    auto cf_name = row.get_nonnull<sstring>("table_name");
    return create_table_from_name(proxy, ks_name, cf_name);
}

static void prepare_builder_from_table_row(const schema_ctxt& ctxt, schema_builder& builder, const query::result_set_row& table_row)
{
    // These row reads have been purposefully reordered to match the origin counterpart. For easier matching.
    if (auto val = table_row.get<double>("bloom_filter_fp_chance")) {
        builder.set_bloom_filter_fp_chance(*val);
    } else {
        builder.set_bloom_filter_fp_chance(builder.get_bloom_filter_fp_chance());
    }

    if (auto map = get_map<sstring, sstring>(table_row, "caching")) {
        builder.set_caching_options(caching_options::from_map(*map));
    }

    if (auto val = table_row.get<sstring>("comment")) {
        builder.set_comment(*val);
    }

    if (auto opt_map = get_map<sstring, sstring>(table_row, "compaction")) {
        auto &map = *opt_map;
        auto i = map.find("class");
        if (i != map.end()) {
            try {
                builder.set_compaction_strategy(sstables::compaction_strategy::type(i->second));
                map.erase(i);
            } catch (const exceptions::configuration_exception& e) {
                // If compaction strategy class isn't supported, fallback to incremental.
                slogger.warn("Falling back to incremental compaction strategy after the problem: {}", e.what());
                builder.set_compaction_strategy(sstables::compaction_strategy_type::incremental);
            }
        }
        if (map.contains("max_threshold")) {
            builder.set_max_compaction_threshold(std::stoi(map["max_threshold"]));
        }
        if (map.contains("min_threshold")) {
            builder.set_min_compaction_threshold(std::stoi(map["min_threshold"]));
        }
        if (map.contains("enabled")) {
            builder.set_compaction_enabled(boost::algorithm::iequals(map["enabled"], "true"));
        }

        builder.set_compaction_strategy_options(std::move(map));
    }

    if (auto map = get_map<sstring, sstring>(table_row, "compression")) {
        compression_parameters cp(*map);
        builder.set_compressor_params(cp);
    }

    if (auto val = table_row.get<int32_t>("default_time_to_live")) {
        builder.set_default_time_to_live(gc_clock::duration(*val));
    }

    if (auto val = get_map<sstring, bytes>(table_row, "extensions")) {
        auto &map = *val;
        schema::extensions_map result;
        auto& exts = ctxt.extensions().schema_extensions();
        for (auto&p : map) {
            auto i = exts.find(p.first);
            if (i != exts.end()) {
                try {
                    auto ep = i->second(p.second);
                    if (ep) {
                        result.emplace(p.first, std::move(ep));
                    }
                    continue;
                } catch (...) {
                    slogger.warn("Error parsing extension {}: {}", p.first, std::current_exception());
                }
            }

            // unknown. we should still preserve it.
            class placeholder : public schema_extension {
                bytes _bytes;
            public:
                // This support code was written before schema_extension was deprecated, so support it
                // without warnings
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
                placeholder(bytes bytes)
                                : _bytes(std::move(bytes)) {
                }
#pragma clang diagnostic pop
                bytes serialize() const override {
                    return _bytes;
                }
                virtual bool is_placeholder() const override {
                    return true;
                }
            };

            result.emplace(p.first, ::make_shared<placeholder>(p.second));
        }
        builder.set_extensions(std::move(result));
    }

    if (auto val = table_row.get<int32_t>("gc_grace_seconds")) {
        builder.set_gc_grace_seconds(*val);
    }

    if (auto val = table_row.get<int>("min_index_interval")) {
        builder.set_min_index_interval(*val);
    }

    if (auto val = table_row.get<int32_t>("memtable_flush_period_in_ms")) {
        builder.set_memtable_flush_period(*val);
    }

    if (auto val = table_row.get<int>("max_index_interval")) {
        builder.set_max_index_interval(*val);
    }

    if (auto val = table_row.get<double>("crc_check_chance")) {
        builder.set_crc_check_chance(*val);
    }

    if (auto val = table_row.get<sstring>("speculative_retry")) {
        builder.set_speculative_retry(*val);
    }
}

static void prepare_builder_from_scylla_tables_row(const schema_ctxt& ctxt, schema_builder& builder, const query::result_set_row& table_row) {
    auto in_mem = table_row.get<bool>("in_memory");
    auto in_mem_enabled = in_mem.value_or(false);
    if (in_mem_enabled) {
        slogger.warn("Support for in_memory tables has been deprecated.");
    }
    builder.set_in_memory(in_mem_enabled);
    if (auto opt_map = get_map<sstring, sstring>(table_row, "tablets")) {
        auto tablet_options = db::tablet_options(*opt_map);
        builder.set_tablet_options(tablet_options.to_map());
    }
}

schema_ptr create_table_from_mutations(const schema_ctxt& ctxt, schema_mutations sm, std::optional<table_schema_version> version)
{
    slogger.trace("create_table_from_mutations: version={}, {}", version, sm);

    auto table_rs = query::result_set(sm.columnfamilies_mutation());
    const query::result_set_row& table_row = table_rs.row(0);

    auto ks_name = table_row.get_nonnull<sstring>("keyspace_name");
    auto cf_name = table_row.get_nonnull<sstring>("table_name");
    auto id = table_id(table_row.get_nonnull<utils::UUID>("id"));
    schema_builder builder{ks_name, cf_name, id};

    auto cf = cf_type::standard;
    auto is_dense = false;
    auto is_counter = false;
    auto is_compound = false;
    auto flags = table_row.get<set_type_impl::native_type>("flags");

    if (flags) {
        for (auto& s : *flags) {
            if (s == "super") {
                // cf = cf_type::super;
                fail(unimplemented::cause::SUPER);
            } else if (s == "dense") {
                is_dense = true;
            } else if (s == "compound") {
                is_compound = true;
            } else if (s == "counter") {
                is_counter = true;
            }
        }
    }

    auto computed_columns = get_computed_columns(sm);
    std::vector<column_definition> column_defs = create_columns_from_column_rows(
            ctxt,
            query::result_set(sm.columns_mutation()),
            ks_name,
            cf_name,/*,
            fullRawComparator, */
            cf == cf_type::super,
            column_view_virtual::no,
            computed_columns);


    builder.set_is_dense(is_dense);
    builder.set_is_compound(is_compound);
    builder.set_is_counter(is_counter);

    prepare_builder_from_table_row(ctxt, builder, table_row);

    if (sm.scylla_tables()) {
        table_rs = query::result_set(*sm.scylla_tables());
        if (!table_rs.empty()) {
            prepare_builder_from_scylla_tables_row(ctxt, builder, table_rs.row(0));
        }
    }
    v3_columns columns(std::move(column_defs), is_dense, is_compound);
    columns.apply_to(builder);

    std::vector<index_metadata> index_defs;
    if (sm.indices_mutation()) {
        index_defs = create_indices_from_index_rows(query::result_set(*sm.indices_mutation()), ks_name, cf_name);
    }
    for (auto&& index : index_defs) {
        builder.with_index(index);
    }

    if (sm.dropped_columns_mutation()) {
        query::result_set dcr(*sm.dropped_columns_mutation());
        for (auto& row : dcr.rows()) {
            auto name = row.get_nonnull<sstring>("column_name");
            auto type = cql_type_parser::parse(ks_name, row.get_nonnull<sstring>("type"), ctxt.user_types());
            auto time = row.get_nonnull<db_clock::time_point>("dropped_time");
            builder.without_column(name, type, time.time_since_epoch().count());
        }
    }

    if (version) {
        builder.with_version(*version);
    } else {
        builder.with_version(sm.digest(ctxt.features().cluster_schema_features()));
    }

    if (auto partitioner = sm.partitioner()) {
        builder.with_partitioner(*partitioner);
        builder.with_sharder(smp::count, ctxt.murmur3_partitioner_ignore_msb_bits());
    }

    return builder.build();
}

/*
 * Column metadata serialization/deserialization.
 */

static void add_column_to_schema_mutation(schema_ptr table,
                                   const column_definition& column,
                                   api::timestamp_type timestamp,
                                   mutation& m)
{
    auto ckey = clustering_key::from_exploded(*m.schema(), {utf8_type->decompose(table->cf_name()),
                                                            utf8_type->decompose(column.name_as_text())});
    fill_column_info(*table, ckey, column, timestamp, std::nullopt, m);
}

static void add_computed_column_to_schema_mutation(schema_ptr table,
        const column_definition& column,
        api::timestamp_type timestamp,
        mutation& m) {
    auto ckey = clustering_key::from_exploded(*m.schema(),
            {utf8_type->decompose(table->cf_name()), utf8_type->decompose(column.name_as_text())});

    m.set_clustered_cell(ckey, "computation", data_value(column.get_computation().serialize()), timestamp);
}

sstring serialize_kind(column_kind kind)
{
    switch (kind) {
    case column_kind::partition_key:  return "partition_key";
    case column_kind::clustering_key: return "clustering";
    case column_kind::static_column:  return "static";
    case column_kind::regular_column: return "regular";
    default:                          throw std::invalid_argument("unknown column kind");
    }
}

column_kind deserialize_kind(sstring kind) {
    if (kind == "partition_key") {
        return column_kind::partition_key;
    } else if (kind == "clustering_key" || kind == "clustering") {
        return column_kind::clustering_key;
    } else if (kind == "static") {
        return column_kind::static_column;
    } else if (kind == "regular") {
        return column_kind::regular_column;
    } else if (kind == "compact_value") { // backward compatibility
        return column_kind::regular_column;
    } else {
        throw std::invalid_argument("unknown column kind: " + kind);
    }
}

sstring serialize_index_kind(index_metadata_kind kind)
{
    switch (kind) {
    case index_metadata_kind::keys:       return "KEYS";
    case index_metadata_kind::composites: return "COMPOSITES";
    case index_metadata_kind::custom:     return "CUSTOM";
    }
    throw std::invalid_argument("unknown index kind");
}

index_metadata_kind deserialize_index_kind(sstring kind) {
    if (kind == "KEYS") {
        return index_metadata_kind::keys;
    } else if (kind == "COMPOSITES") {
        return index_metadata_kind::composites;
    } else if (kind == "CUSTOM") {
        return index_metadata_kind::custom;
    } else {
        throw std::invalid_argument("unknown column kind: " + kind);
    }
}

static void add_index_to_schema_mutation(schema_ptr table,
                                  const index_metadata& index,
                                  api::timestamp_type timestamp,
                                  mutation& m)
{
    auto ckey = clustering_key::from_exploded(*m.schema(), {utf8_type->decompose(table->cf_name()), utf8_type->decompose(index.name())});
    m.set_clustered_cell(ckey, "kind", serialize_index_kind(index.kind()), timestamp);
    store_map(m, ckey, "options", timestamp, index.options());
}

static void drop_index_from_schema_mutation(schema_ptr table, const index_metadata& index, long timestamp, std::vector<mutation>& mutations)
{
    schema_ptr s = indexes();
    auto pkey = partition_key::from_singular(*s, table->ks_name());
    auto ckey = clustering_key::from_exploded(*s, {utf8_type->decompose(table->cf_name()), utf8_type->decompose(index.name())});
    mutation m{s, pkey};
    m.partition().apply_delete(*s, ckey, tombstone(timestamp, gc_clock::now()));
    mutations.push_back(std::move(m));
}

static void drop_column_from_schema_mutation(
        schema_ptr schema_table,
        schema_ptr table,
        const sstring& column_name,
        long timestamp,
        std::vector<mutation>& mutations)
{
    auto pkey = partition_key::from_singular(*schema_table, table->ks_name());
    auto ckey = clustering_key::from_exploded(*schema_table, {utf8_type->decompose(table->cf_name()),
                                                              utf8_type->decompose(column_name)});

    mutation m{schema_table, pkey};
    m.partition().apply_delete(*schema_table, ckey, tombstone(timestamp, gc_clock::now()));
    mutations.emplace_back(m);
}

static computed_columns_map get_computed_columns(const schema_mutations& sm) {
    if (!sm.computed_columns_mutation()) {
        return {};
    }
    query::result_set computed_result(*sm.computed_columns_mutation());
    return computed_result.rows() | std::views::transform([] (const query::result_set_row& row) {
        return computed_columns_map::value_type{to_bytes(row.get_nonnull<sstring>("column_name")), column_computation::deserialize(row.get_nonnull<bytes>("computation"))};
    }) | std::ranges::to<computed_columns_map>();
}

static std::vector<column_definition> create_columns_from_column_rows(const schema_ctxt& ctxt,
                                                               const query::result_set& rows,
                                                               const sstring& keyspace,
                                                               const sstring& table, /*,
                                                               AbstractType<?> rawComparator, */
                                                               bool is_super,
                                                               column_view_virtual is_view_virtual,
                                                               const computed_columns_map& computed_columns)
{
    std::vector<column_definition> columns;
    for (auto&& row : rows.rows()) {
        auto kind = deserialize_kind(row.get_nonnull<sstring>("kind"));
        auto type = cql_type_parser::parse(keyspace, row.get_nonnull<sstring>("type"), ctxt.user_types());
        auto name_bytes = row.get_nonnull<bytes>("column_name_bytes");
        column_id position = row.get_nonnull<int32_t>("position");

        if (auto val = row.get<sstring>("clustering_order")) {
            auto order = *val;
            std::transform(order.begin(), order.end(), order.begin(), ::toupper);
            if (order == "DESC") {
                type = reversed_type_impl::get_instance(type);
            }
        }
        column_computation_ptr computation;
        auto computed_it = computed_columns.find(name_bytes);
        if (computed_it != computed_columns.end()) {
            computation = computed_it->second->clone();
        }

        columns.emplace_back(name_bytes, type, kind, position, is_view_virtual, std::move(computation));
    }
    return columns;
}

static std::vector<index_metadata> create_indices_from_index_rows(const query::result_set& rows,
                                                           const sstring& keyspace,
                                                           const sstring& table)
{
    return rows.rows() | std::views::transform([&keyspace, &table] (auto&& row) {
        return create_index_from_index_row(row, keyspace, table);
    }) | std::ranges::to<std::vector<index_metadata>>();
}

static index_metadata create_index_from_index_row(const query::result_set_row& row,
                                           sstring keyspace,
                                           sstring table)
{
    auto index_name = row.get_nonnull<sstring>("index_name");
    index_options_map options;
    auto map = row.get_nonnull<map_type_impl::native_type>("options");
    for (auto&& entry : map) {
        options.emplace(value_cast<sstring>(entry.first), value_cast<sstring>(entry.second));
    }
    index_metadata_kind kind = deserialize_index_kind(row.get_nonnull<sstring>("kind"));
    sstring target_string = options.at(cql3::statements::index_target::target_option_name);
    const index_metadata::is_local_index is_local(secondary_index::target_parser::is_local(target_string));
    return index_metadata{index_name, options, kind, is_local};
}

static schema_builder prepare_view_schema_builder_from_mutations(const schema_ctxt& ctxt, const schema_mutations& sm, std::optional<table_schema_version> version,
                                                                const query::result_set& table_rs) {
    const query::result_set_row& row = table_rs.row(0);

    auto ks_name = row.get_nonnull<sstring>("keyspace_name");
    auto cf_name = row.get_nonnull<sstring>("view_name");
    auto id = table_id(row.get_nonnull<utils::UUID>("id"));

    schema_builder builder{ks_name, cf_name, id};
    prepare_builder_from_table_row(ctxt, builder, row);

    if (sm.scylla_tables()) {
        auto table_rs = query::result_set(*sm.scylla_tables());
        if (!table_rs.empty()) {
            prepare_builder_from_scylla_tables_row(ctxt, builder, table_rs.row(0));
        }
    }

    auto computed_columns = get_computed_columns(sm);
    auto column_defs = create_columns_from_column_rows(ctxt, query::result_set(sm.columns_mutation()), ks_name, cf_name, false, column_view_virtual::no, computed_columns);
    for (auto&& cdef : column_defs) {
        builder.with_column_ordered(cdef);
    }
    if (sm.view_virtual_columns_mutation()) {
        column_defs = create_columns_from_column_rows(ctxt, query::result_set(*sm.view_virtual_columns_mutation()), ks_name, cf_name, false, column_view_virtual::yes, computed_columns);
        for (auto&& cdef : column_defs) {
            builder.with_column_ordered(cdef);
        }
    }

    if (version) {
        builder.with_version(*version);
    } else {
        builder.with_version(sm.digest(ctxt.features().cluster_schema_features()));
    }
    return builder;
}

/*
 * View metadata serialization/deserialization.
 * If the base info is not provided, the schema context must have a reference to the database,
 * and the most up-to-date base schema will be pulled from there.
 */
view_ptr create_view_from_mutations(const schema_ctxt& ctxt, schema_mutations sm, schema_ptr base_schema, std::optional<table_schema_version> version)  {
    auto table_rs = query::result_set(sm.columnfamilies_mutation());
    auto builder = prepare_view_schema_builder_from_mutations(ctxt, sm, version, table_rs);
    const query::result_set_row& row = table_rs.row(0);
    auto include_all_columns = row.get_nonnull<bool>("include_all_columns");
    auto where_clause = row.get_nonnull<sstring>("where_clause");

    builder.with_view_info(std::move(base_schema), include_all_columns, std::move(where_clause));
    return view_ptr(builder.build());
}

view_ptr create_view_from_mutations(const schema_ctxt& ctxt, schema_mutations sm, std::optional<db::view::base_dependent_view_info> base_info, std::optional<table_schema_version> version)  {
    auto table_rs = query::result_set(sm.columnfamilies_mutation());
    auto builder = prepare_view_schema_builder_from_mutations(ctxt, sm, version, table_rs);
    const query::result_set_row& row = table_rs.row(0);
    auto id = table_id(row.get_nonnull<utils::UUID>("base_table_id"));
    auto base_name = row.get_nonnull<sstring>("base_table_name");
    auto include_all_columns = row.get_nonnull<bool>("include_all_columns");
    auto where_clause = row.get_nonnull<sstring>("where_clause");

    if (!base_info) {
        if (!ctxt.get_db()) {
            auto ks_name = row.get_nonnull<sstring>("keyspace_name");
            auto cf_name = row.get_nonnull<sstring>("view_name");
            on_internal_error(slogger, format("No database reference with missing base schema when creating view {}.{} from mutations",
                ks_name, cf_name));
        }
        auto base_id = table_id(row.get_nonnull<utils::UUID>("base_table_id"));
        auto base_schema = ctxt.get_db()->find_schema(base_id);
        builder.with_view_info(base_schema, include_all_columns, std::move(where_clause));
    } else {
        builder.with_view_info(id, base_name, include_all_columns, std::move(where_clause), *base_info);
    }
    return view_ptr(builder.build());
}

static future<view_ptr> create_view_from_table_row(distributed<service::storage_proxy>& proxy, const query::result_set_row& row) {
    qualified_name qn(row.get_nonnull<sstring>("keyspace_name"), row.get_nonnull<sstring>("view_name"));
    schema_mutations sm = co_await read_table_mutations(proxy, qn, views());
    if (!sm.live()) {
        co_await coroutine::return_exception(std::runtime_error(format("{}:{} not found in the view definitions keyspace.", qn.keyspace_name, qn.table_name)));
    }
    co_return create_view_from_mutations(proxy, std::move(sm));
}

/**
 * Deserialize views from low-level schema representation, all of them belong to the same keyspace
 *
 * @return vector containing the view definitions
 */
future<std::vector<view_ptr>> create_views_from_schema_partition(distributed<service::storage_proxy>& proxy, const schema_result::mapped_type& result)
{
    std::vector<view_ptr> views;
    co_await max_concurrent_for_each(result->rows().begin(), result->rows().end(), max_concurrent, [&] (auto&& row) -> future<> {
        auto v = co_await create_view_from_table_row(proxy, row);
        views.push_back(std::move(v));
    });
    co_return std::move(views);
}

static schema_mutations make_view_mutations(view_ptr view, api::timestamp_type timestamp, bool with_columns)
{
    // When adding new schema properties, don't set cells for default values so that
    // both old and new nodes will see the same version during rolling upgrades.

    // For properties that can be null (and can be changed), we insert tombstones, to make sure
    // we don't keep a property the user has removed
    schema_ptr s = views();
    auto pkey = partition_key::from_singular(*s, view->ks_name());
    mutation m{s, pkey};
    auto ckey = clustering_key::from_singular(*s, view->cf_name());

    m.set_clustered_cell(ckey, "base_table_id", view->view_info()->base_id().uuid(), timestamp);
    m.set_clustered_cell(ckey, "base_table_name", view->view_info()->base_name(), timestamp);
    m.set_clustered_cell(ckey, "where_clause", view->view_info()->where_clause(), timestamp);
    m.set_clustered_cell(ckey, "bloom_filter_fp_chance", view->bloom_filter_fp_chance(), timestamp);
    m.set_clustered_cell(ckey, "include_all_columns", view->view_info()->include_all_columns(), timestamp);
    m.set_clustered_cell(ckey, "id", view->id().uuid(), timestamp);

    add_table_params_to_mutations(m, ckey, view, timestamp);

    mutation columns_mutation(columns(), pkey);
    mutation view_virtual_columns_mutation(view_virtual_columns(), pkey);
    mutation computed_columns_mutation(computed_columns(), pkey);
    mutation dropped_columns_mutation(dropped_columns(), pkey);
    mutation indices_mutation(indexes(), pkey);

    if (with_columns) {
        for (auto&& column : view->v3().all_columns()) {
            if (column.is_view_virtual()) {
                add_column_to_schema_mutation(view, column, timestamp, view_virtual_columns_mutation);
            } else {
                add_column_to_schema_mutation(view, column, timestamp, columns_mutation);
            }
            if (column.is_computed()) {
                add_computed_column_to_schema_mutation(view, column, timestamp, computed_columns_mutation);
            }
        }

        for (auto&& e : view->dropped_columns()) {
            add_dropped_column_to_schema_mutation(view, e.first, e.second, timestamp, dropped_columns_mutation);
        }
        for (auto&& index : view->indices()) {
            add_index_to_schema_mutation(view, index, timestamp, indices_mutation);
        }
    }

    auto scylla_tables_mutation = make_scylla_tables_mutation(view, timestamp);

    return schema_mutations{std::move(m),
                            std::move(columns_mutation),
                            std::move(view_virtual_columns_mutation),
                            std::move(computed_columns_mutation),
                            std::move(indices_mutation),
                            std::move(dropped_columns_mutation),
                            std::move(scylla_tables_mutation)};
}

schema_mutations make_schema_mutations(schema_ptr s, api::timestamp_type timestamp, bool with_columns)
{
    return s->is_view() ? make_view_mutations(view_ptr(s), timestamp, with_columns) : make_table_mutations(s, timestamp, with_columns);
}

std::vector<mutation> make_create_view_mutations(lw_shared_ptr<keyspace_metadata> keyspace, view_ptr view, api::timestamp_type timestamp)
{
    std::vector<mutation> mutations;
    // Include the serialized base table mutations in case the target node is missing them.
    auto base = keyspace->cf_meta_data().at(view->view_info()->base_name());
    // Use a smaller timestamp for the included base mutations.
    // If the constructed schema change command also contains an update for the base table,
    // these mutations would conflict with the base mutations we're returning here; using a smaller
    // timestamp makes sure that the update mutations take precedence. Although there is no known
    // scenario involving creation of new view where this might happen, there is one with updating
    // a view (see `make_update_view_mutations`); we use similarly modified timestamp here for consistency.
    add_table_or_view_to_schema_mutation(base, timestamp - 1, true, mutations);
    add_table_or_view_to_schema_mutation(view, timestamp, true, mutations);
    make_table_deleting_mutations(view->ks_name(), view->cf_name(), view->is_view(), timestamp)
        .copy_to(mutations);
    return mutations;
}

/**
 * Note: new_view can be generated due to an ALTER on its base table; in that
 * case, the new base schema isn't yet loaded, thus can't be accessed from this
 * function.
 */
std::vector<mutation> make_update_view_mutations(lw_shared_ptr<keyspace_metadata> keyspace,
                                                 view_ptr old_view,
                                                 view_ptr new_view,
                                                 api::timestamp_type timestamp,
                                                 bool include_base)
{
    std::vector<mutation> mutations;
    if (include_base) {
        // Include the serialized base table mutations in case the target node is missing them.
        auto base = keyspace->cf_meta_data().at(new_view->view_info()->base_name());
        // Use a smaller timestamp for the included base mutations.
        // If the constructed schema change command also contains an update for the base table,
        // these mutations would conflict with the base mutations we're returning here; using a smaller
        // timestamp makes sure that the update mutations take precedence. Such conflicting mutations
        // may appear, for example, when we modify a user defined type that is referenced by both base table
        // and its attached view. See #15530.
        add_table_or_view_to_schema_mutation(base, timestamp - 1, true, mutations);
    }
    add_table_or_view_to_schema_mutation(new_view, timestamp, false, mutations);
    make_update_columns_mutations(old_view, new_view, timestamp, mutations);
    return mutations;
}

std::vector<mutation> make_drop_view_mutations(lw_shared_ptr<keyspace_metadata> keyspace, view_ptr view, api::timestamp_type timestamp) {
    std::vector<mutation> mutations;
    make_drop_table_or_view_mutations(views(), view, timestamp, mutations);
    return mutations;
}

data_type parse_type(sstring str)
{
    return db::marshal::type_parser::parse(str);
}

std::vector<schema_ptr> all_tables(schema_features features) {
    // Don't forget to update this list when new schema tables are added.
    // The listed schema tables are the ones synchronized between nodes,
    // and forgetting one of them in this list can cause bugs like #4339.
    //
    // This list must be kept backwards-compatible because it's used
    // for schema digest calculation. Refs #4457.
    std::vector<schema_ptr> result = {
        keyspaces(), tables(), scylla_tables(), columns(), dropped_columns(), triggers(),
        views(), types(), functions(), aggregates(), indexes()
    };
    result.emplace_back(view_virtual_columns());
    if (features.contains<schema_feature::COMPUTED_COLUMNS>()) {
        result.emplace_back(computed_columns());
    }
    if (features.contains<schema_feature::SCYLLA_KEYSPACES>()) {
        result.emplace_back(scylla_keyspaces());
    }
    if (features.contains<schema_feature::SCYLLA_AGGREGATES>()) {
        result.emplace_back(scylla_aggregates());
    }
    return result;
}

std::vector<table_info> all_table_infos(schema_features features) {
    return all_tables(features)
        | std::views::transform([] (auto schema) { return table_info{ schema->cf_name(), schema->id() }; })
        | std::ranges::to<std::vector>();
}

void check_no_legacy_secondary_index_mv_schema(replica::database& db, const view_ptr& v, schema_ptr base_schema) {
    // Legacy format for a secondary index used a hardcoded "token" column, which ensured a proper
    // order for indexed queries. This "token" column is has been implemented as a computed column
    // for a long time now, and migration code has been / will be executed on all reasonable Scylla
    // deployments (which don't do unsupported upgrades).
    //
    // This function is now used as a sanity check that we're not dealing with the legacy format anymore.
    if (v->clustering_key_size() == 0) {
        return;
    }
    const auto ck_cols = v->clustering_key_columns();
    const column_definition& first_view_ck = ck_cols.front();
    if (first_view_ck.is_computed()) {
        return;
    }

    if (!base_schema) {
        base_schema = db.find_schema(v->view_info()->base_id());
    }

    // If the first clustering key part of a view is a column with name not found in base schema,
    // and the column is not computed (which we checked above), then it must be backing an index
    // created before computed columns were introduced.
    if (!base_schema->columns_by_name().contains(first_view_ck.name())) {
        on_fatal_internal_error(slogger, format(
            "Materialized view {}.{}: first clustering key column ({}) is not computed and does not have a corresponding"
            " column in the base table. This materialized view must therefore be a secondary index created"
            " using legacy method (without computed columns) that wasn't migrated properly to new method."
            " Make sure that you perform rolling upgrade according to documented procedure without skipping"
            " major Scylla versions.", v->ks_name(), v->cf_name(), first_view_ck.name_as_text()));
    }
}


namespace legacy {

table_schema_version schema_mutations::digest() const {
    md5_hasher h;
    const db::schema_features no_features;
    db::schema_tables::feed_hash_for_schema_digest(h, _columnfamilies, no_features);
    db::schema_tables::feed_hash_for_schema_digest(h, _columns, no_features);
    return table_schema_version(utils::UUID_gen::get_name_UUID(h.finalize()));
}

future<schema_mutations> read_table_mutations(distributed<service::storage_proxy>& proxy,
    sstring keyspace_name, sstring table_name, schema_ptr s)
{
    mutation cf_m = co_await read_schema_partition_for_table(proxy, s, keyspace_name, table_name);
    mutation col_m = co_await read_schema_partition_for_table(proxy, db::system_keyspace::legacy::columns(), keyspace_name, table_name);
    co_return schema_mutations{std::move(cf_m), std::move(col_m)};
}

} // namespace legacy

static auto GET_COLUMN_MAPPING_QUERY = format("SELECT column_name, clustering_order, column_name_bytes, kind, position, type FROM system.{} WHERE cf_id = ? AND schema_version = ?",
    db::schema_tables::SCYLLA_TABLE_SCHEMA_HISTORY);

future<column_mapping> get_column_mapping(db::system_keyspace& sys_ks, ::table_id table_id, table_schema_version version) {
    shared_ptr<cql3::untyped_result_set> results = co_await sys_ks._qp.execute_internal(
        GET_COLUMN_MAPPING_QUERY,
        db::consistency_level::LOCAL_ONE,
        {table_id.uuid(), version.uuid()},
        cql3::query_processor::cache_internal::no
    );
    if (results->empty()) {
        // If we don't have a stored column_mapping for an obsolete schema version
        // then it means it's way too old and been cleaned up already.
        // Fail the whole learn stage in this case.
        co_await coroutine::return_exception(std::runtime_error(
            format("Failed to look up column mapping for schema version {}",
                version)));
    }
    std::vector<column_definition>  static_columns, regular_columns;
    for (const auto& row : *results) {
        auto kind = deserialize_kind(row.get_as<sstring>("kind"));
        auto type = cql_type_parser::parse("" /*unused*/, row.get_as<sstring>("type"), data_dictionary::dummy_user_types_storage());
        auto name_bytes = row.get_blob("column_name_bytes");
        column_id position = row.get_as<int32_t>("position");

        auto order = row.get_as<sstring>("clustering_order");
        std::transform(order.begin(), order.end(), order.begin(), ::toupper);
        if (order == "DESC") {
            type = reversed_type_impl::get_instance(type);
        }
        if (kind == column_kind::static_column) {
            static_columns.emplace_back(name_bytes, type, kind, position);
        } else if (kind == column_kind::regular_column) {
            regular_columns.emplace_back(name_bytes, type, kind, position);
        }
    }
    std::vector<column_mapping_entry> cm_columns;
    for (const column_definition& def : boost::range::join(static_columns, regular_columns)) {
        cm_columns.emplace_back(column_mapping_entry{def.name(), def.type});
    }
    column_mapping cm(std::move(cm_columns), static_columns.size());
    co_return std::move(cm);
}

future<bool> column_mapping_exists(db::system_keyspace& sys_ks, table_id table_id, table_schema_version version) {
    shared_ptr<cql3::untyped_result_set> results = co_await sys_ks._qp.execute_internal(
        GET_COLUMN_MAPPING_QUERY,
        db::consistency_level::LOCAL_ONE,
        {table_id.uuid(), version.uuid()},
        cql3::query_processor::cache_internal::yes
    );
    co_return !results->empty();
}

future<> drop_column_mapping(db::system_keyspace& sys_ks, table_id table_id, table_schema_version version) {
    const static sstring DEL_COLUMN_MAPPING_QUERY =
        format("DELETE FROM system.{} WHERE cf_id = ? and schema_version = ?",
            db::schema_tables::SCYLLA_TABLE_SCHEMA_HISTORY);
    co_await sys_ks._qp.execute_internal(
        DEL_COLUMN_MAPPING_QUERY,
        db::consistency_level::LOCAL_ONE,
        {table_id.uuid(), version.uuid()},
        cql3::query_processor::cache_internal::no);
}

} // namespace schema_tables
} // namespace schema