greenplumn gp_segment_config 源码
greenplumn gp_segment_config 代码
文件路径：/src/backend/catalog/gp_segment_config.c
/*
* gp_segment_config.c
*
* Copyright (c) 2017-Present VMware, Inc. or its affiliates.
*
*/
#include "postgres.h"
#include "catalog/gp_segment_configuration.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "utils/fmgroids.h"
/*
* Tell the caller whether any segment mirrors exist.
*/
bool
gp_segment_config_has_mirrors()
{
bool mirrors_exist;
Relation rel;
ScanKeyData scankey[2];
SysScanDesc scan;
HeapTuple tuple;
rel = heap_open(GpSegmentConfigRelationId, AccessShareLock);
/*
* SELECT dbid FROM gp_segment_configuration
* WHERE content != :1 AND role = :2
*/
ScanKeyInit(&scankey[0],
Anum_gp_segment_configuration_content,
BTEqualStrategyNumber, F_INT2NE,
Int16GetDatum(MASTER_CONTENT_ID));
ScanKeyInit(&scankey[1],
Anum_gp_segment_configuration_role,
BTEqualStrategyNumber, F_CHAREQ,
CharGetDatum('m'));
scan = systable_beginscan(rel, InvalidOid, false,
NULL, 2, scankey);
tuple = systable_getnext(scan);
mirrors_exist = HeapTupleIsValid(tuple);
systable_endscan(scan);
heap_close(rel, AccessShareLock);
return mirrors_exist;
}
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