blob: eece2355f4643511c09601d35a0a5d36e72b6444 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
#pragma once
#include <Interpreters/Context_fwd.h>
#include <Interpreters/DatabaseAndTableWithAlias.h>
namespace DB
{
class ASTSelectQuery;
struct Settings;
/** Predicate optimization based on rewriting ast rules
* For more details : https://github.com/ClickHouse/ClickHouse/pull/2015#issuecomment-374283452
* The optimizer does two different optimizations
* - Move predicates from having to where
* - Push the predicate down from the current query to the having of the subquery
*/
class PredicateExpressionsOptimizer : WithContext
{
public:
PredicateExpressionsOptimizer(ContextPtr context_, const TablesWithColumns & tables_with_columns_, const Settings & settings_);
bool optimize(ASTSelectQuery & select_query);
private:
const bool enable_optimize_predicate_expression;
const bool enable_optimize_predicate_expression_to_final_subquery;
const bool allow_push_predicate_when_subquery_contains_with;
const TablesWithColumns & tables_with_columns;
std::vector<ASTs> extractTablesPredicates(const ASTPtr & where, const ASTPtr & prewhere);
bool tryRewritePredicatesToTables(ASTs & tables_element, const std::vector<ASTs> & tables_predicates);
bool tryRewritePredicatesToTable(
ASTPtr & table_element, const ASTs & table_predicates, const TableWithColumnNamesAndTypes & table_columns) const;
bool tryMovePredicatesFromHavingToWhere(ASTSelectQuery & select_query);
};
}
|
