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This feature allows the vacuum to leverage multiple CPUs in order to process indexes. This enables us to perform index vacuuming and index cleanup with background workers. This adds a PARALLEL option to VACUUM command where the user can specify the number of workers that can be used to perform the command which is limited by the number of indexes on a table. Specifying zero as a number of workers will disable parallelism. This option can't be used with the FULL option. Each index is processed by at most one vacuum process. Therefore parallel vacuum can be used when the table has at least two indexes. The parallel degree is either specified by the user or determined based on the number of indexes that the table has, and further limited by max_parallel_maintenance_workers. The index can participate in parallel vacuum iff it's size is greater than min_parallel_index_scan_size. Author: Masahiko Sawada and Amit Kapila Reviewed-by: Dilip Kumar, Amit Kapila, Robert Haas, Tomas Vondra, Mahendra Singh and Sergei Kornilov Tested-by: Mahendra Singh and Prabhat Sahu Discussion: https://postgr.es/m/CAD21AoDTPMgzSkV4E3SFo1CH_x50bf5PqZFQf4jmqjk-C03BWg@mail.gmail.com https://postgr.es/m/CAA4eK1J-VoR9gzS5E75pcD-OH0mEyCdp8RihcwKrcuw7J-Q0+w@mail.gmail.com
83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* parallel.h
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* Infrastructure for launching parallel workers
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*
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* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/parallel.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PARALLEL_H
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#define PARALLEL_H
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#include "access/xlogdefs.h"
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#include "lib/ilist.h"
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#include "postmaster/bgworker.h"
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#include "storage/shm_mq.h"
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#include "storage/shm_toc.h"
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typedef void (*parallel_worker_main_type) (dsm_segment *seg, shm_toc *toc);
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typedef struct ParallelWorkerInfo
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{
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BackgroundWorkerHandle *bgwhandle;
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shm_mq_handle *error_mqh;
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int32 pid;
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} ParallelWorkerInfo;
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typedef struct ParallelContext
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{
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dlist_node node;
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SubTransactionId subid;
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int nworkers; /* Maximum number of workers to launch */
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int nworkers_to_launch; /* Actual number of workers to launch */
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int nworkers_launched;
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char *library_name;
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char *function_name;
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ErrorContextCallback *error_context_stack;
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shm_toc_estimator estimator;
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dsm_segment *seg;
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void *private_memory;
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shm_toc *toc;
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ParallelWorkerInfo *worker;
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int nknown_attached_workers;
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bool *known_attached_workers;
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} ParallelContext;
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typedef struct ParallelWorkerContext
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{
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dsm_segment *seg;
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shm_toc *toc;
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} ParallelWorkerContext;
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extern volatile bool ParallelMessagePending;
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extern PGDLLIMPORT int ParallelWorkerNumber;
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extern PGDLLIMPORT bool InitializingParallelWorker;
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#define IsParallelWorker() (ParallelWorkerNumber >= 0)
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extern ParallelContext *CreateParallelContext(const char *library_name,
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const char *function_name, int nworkers);
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extern void InitializeParallelDSM(ParallelContext *pcxt);
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extern void ReinitializeParallelDSM(ParallelContext *pcxt);
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extern void ReinitializeParallelWorkers(ParallelContext *pcxt, int nworkers_to_launch);
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extern void LaunchParallelWorkers(ParallelContext *pcxt);
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extern void WaitForParallelWorkersToAttach(ParallelContext *pcxt);
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extern void WaitForParallelWorkersToFinish(ParallelContext *pcxt);
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extern void DestroyParallelContext(ParallelContext *pcxt);
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extern bool ParallelContextActive(void);
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extern void HandleParallelMessageInterrupt(void);
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extern void HandleParallelMessages(void);
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extern void AtEOXact_Parallel(bool isCommit);
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extern void AtEOSubXact_Parallel(bool isCommit, SubTransactionId mySubId);
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extern void ParallelWorkerReportLastRecEnd(XLogRecPtr last_xlog_end);
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extern void ParallelWorkerMain(Datum main_arg);
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#endif /* PARALLEL_H */
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