greenplumn appendonlywriter 源码
greenplumn appendonlywriter 代码
文件路径：/src/include/access/appendonlywriter.h
/*-------------------------------------------------------------------------
*
* appendonlywriter.h
* Definitions for appendonlywriter.c
*
* Portions Copyright (c) 2006-2008, Greenplum inc.
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/include/access/appendonlywriter.h
*
*-------------------------------------------------------------------------
*/
#ifndef APPENDONLYWRITER_H
#define APPENDONLYWRITER_H
#include "access/aosegfiles.h"
/*
* Maximum concurrent number of writes into a single append only table.
* TODO: may want to make this a guc instead (can only be set at gpinit time).
*/
#define MAX_AOREL_CONCURRENCY 128
/*
* Segfile 0 is reserved for special case write operations that don't need
* to worry about concurrency. Currently these are:
*
* - Table rewrites that are sometimes done as a part of ALTER TABLE.
* - CTAS, which runs on an exclusively locked destination table.
*
* There's no particular reason those operations couldn't use the normal
* routines for finding a target segment, but this is historical behavior.
* Similarly, the normal routines don't choose segfile 0, but there's no
* particular reason reason it couldn't be used for normal operations.
*/
#define RESERVED_SEGNO 0
/*
* functions in appendonlywriter.c
*/
extern void LockSegnoForWrite(Relation rel, int segno);
extern int ChooseSegnoForWrite(Relation rel);
extern int ChooseSegnoForCompactionWrite(Relation rel, List *avoid_segnos);
extern int ChooseSegnoForCompaction(Relation rel, List *avoidsegnos);
extern void AORelIncrementModCount(Relation parentrel);
#endif /* APPENDONLYWRITER_H */
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