734a9934a6
Allow disabling tombstone gc on a per-query basis for mutation queries. This is achieved by a bool flag passed to mutation query variants like `query_mutations_on_all_shards()` and `database::mutation_query()`, which is then propagated down to compaction_mutation_state. The future user (in the next patch) is the SELECT * FROM MUTATION_FRAGMENTS() statement which wants to see dead partitions (and rows) when scanning a table. Currently, due to garbage collections, said statement can miss partitions which only contain garbage-collectible tombstones.
93 lines
3.4 KiB
C++
93 lines
3.4 KiB
C++
/*
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* Copyright (C) 2018-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#pragma once
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#include "replica/database_fwd.hh"
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#include "schema/schema_fwd.hh"
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#include "replica/cache_temperature.hh"
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#include "db/timeout_clock.hh"
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#include "dht/i_partitioner_fwd.hh"
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#include <seastar/core/sharded.hh>
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#include "seastarx.hh"
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class reconcilable_result;
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namespace query {
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class read_command;
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class result;
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class result_options;
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} // namespace query
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namespace tracing {
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class trace_state_ptr;
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} // namespace tracing
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namespace replica {
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/// Run the mutation query on all shards.
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///
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/// Under the hood it uses a multishard_combining_reader for reading the
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/// range(s) from all shards.
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///
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/// The query uses paging. The read will stop after reaching one of the page
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/// size limits. Page size is determined by the read_command (row and partition
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/// limits) and by the max_size parameter (max memory size of results).
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///
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/// Optionally the query can be stateful. This means that after filling the
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/// page, the shard readers are saved in the `querier_cache` on their home shard
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/// (wrapped in a `shard_mutation_querier`). Fragments already read from
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/// the shard readers, but not consumed by the results builder (due to
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/// reaching the limit), are extracted from the `multishard_combining_reader`'s
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/// (and the foreign readers wrapping the shard readers) buffers and pushed back
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/// into the shard reader they originated from. This way only the shard readers
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/// have to be cached in order to continue the query.
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/// When reading the next page these querier objects are looked up from
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/// their respective shard's `querier_cache`, instead of creating new shard
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/// readers.
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/// To enable stateful queries set the `query_uuid` field of the read command
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/// to an id unique to the query. This can be easily achieved by generating a
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/// random uuid with `utils::make_random_uuid()`.
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/// It is advisable that the `is_first_page` flag of the read command is set on
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/// the first page of the query so that a pointless lookup is avoided.
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///
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/// Note: params passed by reference are expected to be kept alive by the caller
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/// for the duration of the query. Params passed by const reference are expected
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/// to *not* change during the query, as they will possibly be accessed from
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/// other shards.
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///
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/// \see multishard_combined_reader
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/// \see querier_cache
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future<std::tuple<foreign_ptr<lw_shared_ptr<reconcilable_result>>, cache_temperature>> query_mutations_on_all_shards(
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sharded<replica::database>& db,
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schema_ptr s,
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const query::read_command& cmd,
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const dht::partition_range_vector& ranges,
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tracing::trace_state_ptr trace_state,
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db::timeout_clock::time_point timeout,
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bool tombstone_gc_enabled = true);
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/// Run the data query on all shards.
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///
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/// Identical to `query_mutations_on_all_shards()` except that it builds results
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/// in the `query::result` format instead of in the `reconcilable_result` one.
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future<std::tuple<foreign_ptr<lw_shared_ptr<query::result>>, cache_temperature>> query_data_on_all_shards(
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sharded<replica::database>& db,
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schema_ptr s,
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const query::read_command& cmd,
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const dht::partition_range_vector& ranges,
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query::result_options opts,
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tracing::trace_state_ptr trace_state,
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db::timeout_clock::time_point timeout);
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} // namespace replica
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