3cff10f756
When presented with queries that use the same named bind variables twice, like this one: ```cql SELECT p FROM table WHERE p = :x AND c = :x ``` Scylla generated empty partition_key_bind_indexes (pk_indexes). pk_indexes tell the driver which bind variables it should use to calculate the partition token for a query. Without it, the driver is unable to determine the token and it will send the query to a random node. Scylla should generate pk_indexes which tell the driver that it can use bind variable with bind_index = 0 to calculate the partition token for a query. The problem was that _target_columns keep only a single target_column for each bind variable. In the example above :x is compared with both p and c, but _target_columns would contain only one of them, and Scylla wasn't able to tell that this bind variable is compared with a partition key column. To fix it, let's replace _target_columns with _targets. _targets keeps all comparisons between bind variables and other expressions, so none of them will be forgotten/overwritten. Fixes: #15374 Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
/*
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* Copyright (C) 2015-present ScyllaDB
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*
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* Modified by ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: (AGPL-3.0-or-later and Apache-2.0)
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*/
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#pragma once
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#include <seastar/core/shared_ptr.hh>
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#include "seastarx.hh"
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#include <optional>
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#include <vector>
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#include <stddef.h>
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#include "cql3/expr/expression.hh"
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class schema;
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namespace cql3 {
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class column_identifier;
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class column_specification;
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namespace functions { class function_call; }
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/**
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* Metadata class currently holding bind variables specifications and
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* `function_call` AST nodes inside a query partition key restrictions.
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* Populated and maintained at "prepare" step of query execution.
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*/
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class prepare_context final {
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private:
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// Keeps names of all the bind variables. For bind variables without a name ('?'), the name is nullptr.
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// Maps bind_index -> name.
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std::vector<shared_ptr<column_identifier>> _variable_names;
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// Keeps column_specification for every bind_index. column_specification describes the name and type of this variable.
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std::vector<lw_shared_ptr<column_specification>> _variable_specs;
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// For every expression like (<target> = <bind variable>), there's a pair of (bind_index, target column_specification) in _targets.
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// Collecting all equalities of bind variables allows to determine which of the variables set the value of partition key columns.
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// The driver needs this information in order to compute the partition token and send the request to the right node.
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std::vector<std::pair<std::size_t, lw_shared_ptr<column_specification>>> _targets;
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// A list of pointers to prepared `function_call` cache ids, that
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// participate in partition key ranges computation within an LWT statement.
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std::vector<::shared_ptr<std::optional<uint8_t>>> _pk_function_calls_cache_ids;
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// The flag denoting whether the context is currently in partition key
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// processing mode (inside query restrictions AST nodes). If set to true,
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// then every `function_call` instance will be recorded in the context and
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// will be assigned an identifier, which will then be used for caching
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// the function call results.
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bool _processing_pk_restrictions = false;
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public:
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prepare_context() = default;
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size_t bound_variables_size() const;
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const std::vector<lw_shared_ptr<column_specification>>& get_variable_specifications() const &;
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std::vector<lw_shared_ptr<column_specification>> get_variable_specifications() &&;
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std::vector<uint16_t> get_partition_key_bind_indexes(const schema& schema) const;
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void add_variable_specification(int32_t bind_index, lw_shared_ptr<column_specification> spec);
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void set_bound_variables(const std::vector<shared_ptr<column_identifier>>& bind_variable_names);
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void clear_pk_function_calls_cache();
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// Record a new function call, which evaluates a partition key constraint.
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// Also automatically assigns an id to the AST node for caching purposes.
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void add_pk_function_call(cql3::expr::function_call& fn);
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// Inform the context object that it has started or ended processing the
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// partition key part of statement restrictions.
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void set_processing_pk_restrictions(bool flag) noexcept {
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_processing_pk_restrictions = flag;
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}
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bool is_processing_pk_restrictions() const noexcept {
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return _processing_pk_restrictions;
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}
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};
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}
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