mirror of
https://git.postgresql.org/git/postgresql.git
synced 2026-02-07 05:07:38 +08:00
804163bc25
If there are two different aggregates in the query with same inputs, and the aggregates have the same initial condition and transition function, only calculate the state value once, and only call the final functions separately. For example, AVG(x) and SUM(x) aggregates have the same transition function, which accumulates the sum and number of input tuples. For a query like "SELECT AVG(x), SUM(x) FROM x", we can therefore accumulate the state function only once, which gives a nice speedup. David Rowley, reviewed and edited by me.
58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* parse_agg.h
|
|
* handle aggregates and window functions in parser
|
|
*
|
|
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/parser/parse_agg.h
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef PARSE_AGG_H
|
|
#define PARSE_AGG_H
|
|
|
|
#include "parser/parse_node.h"
|
|
|
|
extern void transformAggregateCall(ParseState *pstate, Aggref *agg,
|
|
List *args, List *aggorder,
|
|
bool agg_distinct);
|
|
|
|
extern Node *transformGroupingFunc(ParseState *pstate, GroupingFunc *g);
|
|
|
|
extern void transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
|
|
WindowDef *windef);
|
|
|
|
extern void parseCheckAggregates(ParseState *pstate, Query *qry);
|
|
|
|
extern List *expand_grouping_sets(List *groupingSets, int limit);
|
|
|
|
extern int get_aggregate_argtypes(Aggref *aggref, Oid *inputTypes);
|
|
|
|
extern Oid resolve_aggregate_transtype(Oid aggfuncid,
|
|
Oid aggtranstype,
|
|
Oid *inputTypes,
|
|
int numArguments);
|
|
|
|
extern void build_aggregate_transfn_expr(Oid *agg_input_types,
|
|
int agg_num_inputs,
|
|
int agg_num_direct_inputs,
|
|
bool agg_variadic,
|
|
Oid agg_state_type,
|
|
Oid agg_input_collation,
|
|
Oid transfn_oid,
|
|
Oid invtransfn_oid,
|
|
Expr **transfnexpr,
|
|
Expr **invtransfnexpr);
|
|
|
|
extern void build_aggregate_finalfn_expr(Oid *agg_input_types,
|
|
int num_finalfn_inputs,
|
|
Oid agg_state_type,
|
|
Oid agg_result_type,
|
|
Oid agg_input_collation,
|
|
Oid finalfn_oid,
|
|
Expr **finalfnexpr);
|
|
|
|
#endif /* PARSE_AGG_H */
|