mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-10-03 17:26:55 +02:00
3452dc5240
If we only need, say, 10 tuples in total, then we certainly don't need more than 10 tuples from any single process. Pushing down the limit lets workers exit early when possible. For Gather Merge, there is an additional benefit: a Sort immediately below the Gather Merge can be done as a bounded sort if there is an applicable limit. Robert Haas and Tom Lane Discussion: http://postgr.es/m/CA+TgmoYa3QKKrLj5rX7UvGqhH73G1Li4B-EKxrmASaca2tFu9Q@mail.gmail.com
44 lines
1.3 KiB
C
44 lines
1.3 KiB
C
/*--------------------------------------------------------------------
|
|
* execParallel.h
|
|
* POSTGRES parallel execution interface
|
|
*
|
|
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* IDENTIFICATION
|
|
* src/include/executor/execParallel.h
|
|
*--------------------------------------------------------------------
|
|
*/
|
|
|
|
#ifndef EXECPARALLEL_H
|
|
#define EXECPARALLEL_H
|
|
|
|
#include "access/parallel.h"
|
|
#include "nodes/execnodes.h"
|
|
#include "nodes/parsenodes.h"
|
|
#include "nodes/plannodes.h"
|
|
#include "utils/dsa.h"
|
|
|
|
typedef struct SharedExecutorInstrumentation SharedExecutorInstrumentation;
|
|
|
|
typedef struct ParallelExecutorInfo
|
|
{
|
|
PlanState *planstate;
|
|
ParallelContext *pcxt;
|
|
BufferUsage *buffer_usage;
|
|
SharedExecutorInstrumentation *instrumentation;
|
|
shm_mq_handle **tqueue;
|
|
dsa_area *area;
|
|
bool finished;
|
|
} ParallelExecutorInfo;
|
|
|
|
extern ParallelExecutorInfo *ExecInitParallelPlan(PlanState *planstate,
|
|
EState *estate, int nworkers, int64 tuples_needed);
|
|
extern void ExecParallelFinish(ParallelExecutorInfo *pei);
|
|
extern void ExecParallelCleanup(ParallelExecutorInfo *pei);
|
|
extern void ExecParallelReinitialize(ParallelExecutorInfo *pei);
|
|
|
|
extern void ParallelQueryMain(dsm_segment *seg, shm_toc *toc);
|
|
|
|
#endif /* EXECPARALLEL_H */
|