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158 lines
5.1 KiB
C++
158 lines
5.1 KiB
C++
#pragma once
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#include <AggregateFunctions/AggregateFunctionFactory.h>
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#include <DataTypes/DataTypeFactory.h>
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#include <Functions/FunctionFactory.h>
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#include <IO/WriteHelpers.h>
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#include <Interpreters/InDepthNodeVisitor.h>
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#include <Interpreters/IdentifierSemantic.h>
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#include <Parsers/ASTFunction.h>
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#include <Parsers/ASTIdentifier.h>
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#include <Parsers/ASTOrderByElement.h>
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#include <Parsers/ASTTablesInSelectQuery.h>
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#include <Parsers/IAST.h>
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#include <Common/typeid_cast.h>
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namespace DB
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{
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using Monotonicity = IFunctionBase::Monotonicity;
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/// Checks from bottom to top if function composition is monotonous
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class MonotonicityCheckMatcher
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{
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public:
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struct Data
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{
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const TablesWithColumns & tables;
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ContextPtr context;
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const std::unordered_set<String> & group_by_function_hashes;
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Monotonicity monotonicity = { .is_monotonic = true, .is_positive = true, .is_always_monotonic = true };
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ASTIdentifier * identifier = nullptr;
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DataTypePtr arg_data_type = {};
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void reject() { monotonicity.is_monotonic = false; }
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bool isRejected() const { return !monotonicity.is_monotonic; }
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bool canOptimize(const ASTFunction & ast_function) const
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{
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/// if GROUP BY contains the same function ORDER BY shouldn't be optimized
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const auto hash = ast_function.getTreeHash(/*ignore_aliases=*/ true);
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const auto key = toString(hash);
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if (group_by_function_hashes.count(key))
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return false;
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/// if ORDER BY contains aggregate function or window functions, it
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/// shouldn't be optimized
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if (ast_function.is_window_function
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|| AggregateUtils::isAggregateFunction(ast_function))
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{
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return false;
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}
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return true;
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}
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bool extractIdentifierAndType(const ASTFunction & ast_function)
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{
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if (identifier)
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return true;
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identifier = ast_function.arguments->children[0]->as<ASTIdentifier>();
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if (!identifier)
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return false;
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auto pos = IdentifierSemantic::getMembership(*identifier);
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if (!pos)
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pos = IdentifierSemantic::chooseTableColumnMatch(*identifier, tables, true);
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if (!pos)
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return false;
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/// It is possible that tables list is empty.
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/// IdentifierSemantic get the position from AST, and it can be not valid to use it.
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/// Example is re-analysing a part of AST for storage Merge, see 02147_order_by_optimizations.sql
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if (*pos >= tables.size())
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return false;
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if (auto data_type_and_name = tables[*pos].columns.tryGetByName(identifier->shortName()))
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{
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arg_data_type = data_type_and_name->type;
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return true;
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}
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return false;
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}
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};
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static void visit(const ASTPtr & ast, Data & data)
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{
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if (const auto * ast_function = ast->as<ASTFunction>())
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visit(*ast_function, data);
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}
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static void visit(const ASTFunction & ast_function, Data & data)
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{
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if (data.isRejected())
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return;
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/// TODO: monotonicity for functions of several arguments
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if (!ast_function.arguments || ast_function.arguments->children.size() != 1)
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{
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data.reject();
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return;
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}
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if (!data.canOptimize(ast_function))
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{
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data.reject();
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return;
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}
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const auto & function = FunctionFactory::instance().tryGet(ast_function.name, data.context);
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if (!function)
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{
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data.reject();
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return;
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}
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/// First time extract the most enclosed identifier and its data type
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if (!data.arg_data_type && !data.extractIdentifierAndType(ast_function))
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{
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data.reject();
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return;
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}
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ColumnsWithTypeAndName args;
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args.emplace_back(data.arg_data_type, "tmp");
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auto function_base = function->build(args);
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if (function_base && function_base->hasInformationAboutMonotonicity())
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{
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bool is_positive = data.monotonicity.is_positive;
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data.monotonicity = function_base->getMonotonicityForRange(*data.arg_data_type, Field(), Field());
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if (!is_positive)
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data.monotonicity.is_positive = !data.monotonicity.is_positive;
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data.arg_data_type = function_base->getResultType();
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}
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else
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data.reject();
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}
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static bool needChildVisit(const ASTPtr & parent, const ASTPtr &)
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{
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/// Currently we check monotonicity only for single-argument functions.
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/// Although, multi-argument functions with all but one constant arguments can also be monotonic.
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if (const auto * func = typeid_cast<const ASTFunction *>(parent.get()))
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return func->arguments->children.size() < 2;
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return true;
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}
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};
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using MonotonicityCheckVisitor = ConstInDepthNodeVisitor<MonotonicityCheckMatcher, false>;
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}
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