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Better "optimize_move_to_prewhere" heuristic

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This commit is contained in:
Alexey Milovidov 2019-02-14 19:48:41 +03:00
parent 6cf3d8c151
commit a216cba3c4
2 changed files with 11 additions and 9 deletions
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14
dbms/src/Storages/MergeTree/MergeTreeWhereOptimizer.cpp
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@ -42,12 +42,14 @@ MergeTreeWhereOptimizer::MergeTreeWhereOptimizer(
const MergeTreeData & data,
const Names & column_names,
Logger * log)
: primary_key_columns{ext::collection_cast<std::unordered_set>(data.primary_key_columns)},
table_columns{ext::map<std::unordered_set>(data.getColumns().getAllPhysical(),
: table_columns{ext::map<std::unordered_set>(data.getColumns().getAllPhysical(),
[] (const NameAndTypePair & col) { return col.name; })},
block_with_constants{KeyCondition::getBlockWithConstants(query_info.query, query_info.syntax_analyzer_result, context)},
log{log}
{
if (!data.primary_key_columns.empty())
first_primary_key_column = data.primary_key_columns[0];
calculateColumnSizes(data, column_names);
auto & select = typeid_cast<ASTSelectQuery &>(*query_info.query);
determineArrayJoinedNames(select);
@ -128,7 +130,7 @@ void MergeTreeWhereOptimizer::optimizeConjunction(ASTSelectQuery & select, ASTFu
IdentifierNameSet identifiers{};
collectIdentifiersNoSubqueries(condition, identifiers);
/// do not take into consideration the conditions consisting only of primary key columns
/// do not take into consideration the conditions consisting only of the first primary key column
if (!hasPrimaryKeyAtoms(condition) && isSubsetOfTableColumns(identifiers))
{
/// calculate size of columns involved in condition
@ -332,9 +334,9 @@ bool MergeTreeWhereOptimizer::isPrimaryKeyAtom(const IAST * const ast) const
const auto & first_arg_name = args.front()->getColumnName();
const auto & second_arg_name = args.back()->getColumnName();
if ((primary_key_columns.count(first_arg_name) && isConstant(args[1])) ||
(primary_key_columns.count(second_arg_name) && isConstant(args[0])) ||
(primary_key_columns.count(first_arg_name) && functionIsInOrGlobalInOperator(func->name)))
if ((first_primary_key_column == first_arg_name && isConstant(args[1]))
|| (first_primary_key_column == second_arg_name && isConstant(args[0]))
|| (first_primary_key_column == first_arg_name && functionIsInOrGlobalInOperator(func->name)))
return true;
}

6
dbms/src/Storages/MergeTree/MergeTreeWhereOptimizer.h
View File

@ -72,10 +72,10 @@ private:
void determineArrayJoinedNames(ASTSelectQuery & select);
using string_set_t = std::unordered_set<std::string>;
using StringSet = std::unordered_set<std::string>;
const string_set_t primary_key_columns;
const string_set_t table_columns;
String first_primary_key_column;
const StringSet table_columns;
const Block block_with_constants;
Poco::Logger * log;
std::unordered_map<std::string, size_t> column_sizes{};