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postgres/src/include/executor/execParallel.h

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Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
/*--------------------------------------------------------------------
* execParallel.h
* POSTGRES parallel execution interface
*
Update copyright via script for 2017
9 years ago
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
* 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"
Provide a DSA area for all parallel queries. This will allow future parallel query code to dynamically allocate storage shared by all participants. Thomas Munro, with assorted changes by me.
9 years ago
#include "utils/dsa.h"
Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
typedef struct SharedExecutorInstrumentation SharedExecutorInstrumentation;
typedef struct ParallelExecutorInfo
{
pgindent run for 9.6
10 years ago
PlanState *planstate;
Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
ParallelContext *pcxt;
BufferUsage *buffer_usage;
SharedExecutorInstrumentation *instrumentation;
shm_mq_handle **tqueue;
Provide a DSA area for all parallel queries. This will allow future parallel query code to dynamically allocate storage shared by all participants. Thomas Munro, with assorted changes by me.
9 years ago
dsa_area *area;
pgindent run for 9.6
10 years ago
bool finished;
} ParallelExecutorInfo;
Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
extern ParallelExecutorInfo *ExecInitParallelPlan(PlanState *planstate,
EState *estate, int nworkers);
extern void ExecParallelFinish(ParallelExecutorInfo *pei);
Rewrite interaction of parallel mode with parallel executor support. In the previous coding, before returning from ExecutorRun, we'd shut down all parallel workers. This was dead wrong if ExecutorRun was called with a non-zero tuple count; it had the effect of truncating the query output. To fix, give ExecutePlan control over whether to enter parallel mode, and have it refuse to do so if the tuple count is non-zero. Rewrite the Gather logic so that it can cope with being called outside parallel mode. Commit 7aea8e4f2daa4b39ca9d1309a0c4aadb0f7ed81b is largely to blame for this problem, though this patch modifies some subsequently-committed code which relied on the guarantees it purported to make.
10 years ago
extern void ExecParallelCleanup(ParallelExecutorInfo *pei);
Avoid aggregating worker instrumentation multiple times. Amit Kapila, per design ideas from me.
10 years ago
extern void ExecParallelReinitialize(ParallelExecutorInfo *pei);
Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
Avoid passing function pointers across process boundaries. We'd already recognized that we can't pass function pointers across process boundaries for functions in loadable modules, since a shared library could get loaded at different addresses in different processes. But actually the practice doesn't work for functions in the core backend either, if we're using EXEC_BACKEND. This is the cause of recent failures on buildfarm member culicidae. Switch to passing a string function name in all cases. Something like this needs to be back-patched into 9.6, but let's see if the buildfarm likes it first. Petr Jelinek, with a bunch of basically-cosmetic adjustments by me Discussion: https://postgr.es/m/548f9c1d-eafa-e3fa-9da8-f0cc2f654e60@2ndquadrant.com
9 years ago
extern void ParallelQueryMain(dsm_segment *seg, shm_toc *toc);
Parallel executor support. This code provides infrastructure for a parallel leader to start up parallel workers to execute subtrees of the plan tree being executed in the master. User-supplied parameters from ParamListInfo are passed down, but PARAM_EXEC parameters are not. Various other constructs, such as initplans, subplans, and CTEs, are also not currently shared. Nevertheless, there's enough here to support a basic implementation of parallel query, and we can lift some of the current restrictions as needed. Amit Kapila and Robert Haas
10 years ago
#endif /* EXECPARALLEL_H */