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87 lines
2.8 KiB
C++
87 lines
2.8 KiB
C++
#pragma once
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#include <Core/NamesAndTypes.h>
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#include <Interpreters/Aliases.h>
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#include <Interpreters/SelectQueryOptions.h>
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#include <Storages/IStorage_fwd.h>
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namespace DB
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{
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NameSet removeDuplicateColumns(NamesAndTypesList & columns);
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class ASTFunction;
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class AnalyzedJoin;
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class Context;
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struct SelectQueryOptions;
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struct SyntaxAnalyzerResult
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{
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StoragePtr storage;
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std::shared_ptr<AnalyzedJoin> analyzed_join;
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NamesAndTypesList source_columns;
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/// Set of columns that are enough to read from the table to evaluate the expression. It does not include joined columns.
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NamesAndTypesList required_source_columns;
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Aliases aliases;
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std::vector<const ASTFunction *> aggregates;
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/// Which column is needed to be ARRAY-JOIN'ed to get the specified.
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/// For example, for `SELECT s.v ... ARRAY JOIN a AS s` will get "s.v" -> "a.v".
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NameToNameMap array_join_result_to_source;
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/// For the ARRAY JOIN section, mapping from the alias to the full column name.
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/// For example, for `ARRAY JOIN [1,2] AS b` "b" -> "array(1,2)" will enter here.
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/// Note: not used further.
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NameToNameMap array_join_alias_to_name;
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/// The backward mapping for array_join_alias_to_name.
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/// Note: not used further.
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NameToNameMap array_join_name_to_alias;
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/// Predicate optimizer overrides the sub queries
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bool rewrite_subqueries = false;
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void collectUsedColumns(const ASTPtr & query, const NamesAndTypesList & additional_source_columns);
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Names requiredSourceColumns() const { return required_source_columns.getNames(); }
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};
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using SyntaxAnalyzerResultPtr = std::shared_ptr<const SyntaxAnalyzerResult>;
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/// AST syntax analysis.
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/// Optimises AST tree and collect information for further expression analysis.
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/// Result AST has the following invariants:
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/// * all aliases are substituted
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/// * qualified names are translated
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/// * scalar subqueries are executed replaced with constants
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/// * unneeded columns are removed from SELECT clause
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/// * duplicated columns are removed from ORDER BY, LIMIT BY, USING(...).
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/// Motivation:
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/// * group most of the AST-changing operations in single place
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/// * avoid AST rewriting in ExpressionAnalyzer
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/// * decompose ExpressionAnalyzer
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class SyntaxAnalyzer
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{
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public:
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SyntaxAnalyzer(const Context & context_, const SelectQueryOptions & select_options = {})
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: context(context_)
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, subquery_depth(select_options.subquery_depth)
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, remove_duplicates(select_options.remove_duplicates)
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{}
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SyntaxAnalyzerResultPtr analyze(
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ASTPtr & query,
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const NamesAndTypesList & source_columns_,
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const Names & required_result_columns = {},
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StoragePtr storage = {},
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const NamesAndTypesList & additional_source_columns = {}) const;
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private:
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const Context & context;
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size_t subquery_depth;
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bool remove_duplicates;
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};
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}
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