greenplumn gp_distribution_policy 源码
greenplumn gp_distribution_policy 代码
文件路径：/gpcontrib/gp_distribution_policy/gp_distribution_policy.c
/*
* Copyright (c) 2013 EMC Corporation All Rights Reserved
*
* This software is protected, without limitation, by copyright law
* and international treaties. Use of this software and the intellectual
* property contained therein is expressly limited to the terms and
* conditions of the License Agreement under which it is provided by
* or on behalf of EMC.
*
* ---------------------------------------------------------------------
*
* Interface to functions related to checking the correct distribution in GPDB.
*
* This is used to expose these functions in a dynamically linked library
* so that they can be referenced by using CREATE FUNCTION command in SQL,
* like below:
*
*CREATE OR REPLACE FUNCTION gp_distribution_policy_table_check(oid, smallint[])
* RETURNS bool
* AS '$libdir/gp_distribution_policy.so','gp_distribution_policy_table_check'
* LANGUAGE C VOLATILE STRICT; *
*/
#include "postgres.h"
#include "access/table.h"
#include "access/tableam.h"
#include "fmgr.h"
#include "funcapi.h"
#include "access/table.h"
#include "utils/builtins.h"
#include "utils/snapmgr.h"
#include "cdb/cdbhash.h"
#include "cdb/cdbvars.h"
#include "utils/lsyscache.h"
#include "miscadmin.h"
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
extern Datum gp_distribution_policy_table_check(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(gp_distribution_policy_table_check);
/*
* Verifies the correct data distribution (given a GpPolicy)
* of a table in a segment.
*/
Datum
gp_distribution_policy_table_check(PG_FUNCTION_ARGS)
{
Oid relOid = PG_GETARG_OID(0);
bool result = true;
TupleTableSlot *slot;
/* Open relation in segment */
Relation rel = table_open(relOid, AccessShareLock);
GpPolicy *policy = rel->rd_cdbpolicy;
/* Validate that the relation is a table */
if (rel->rd_rel->relkind != RELKIND_RELATION &&
rel->rd_rel->relkind != RELKIND_MATVIEW)
{
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("input relation is not a table")));
}
slot = table_slot_create(rel, NULL);
TableScanDesc scandesc = table_beginscan(rel, GetActiveSnapshot(), 0, NULL);
/* Initialize hash function and structure */
CdbHash *hash;
hash = makeCdbHashForRelation(rel);
while (table_scan_getnextslot(scandesc, ForwardScanDirection, slot))
{
CHECK_FOR_INTERRUPTS();
cdbhashinit(hash);
/* Add every attribute in the distribution policy to the hash */
for (int i = 0; i < policy->nattrs; i++)
{
int attnum = policy->attrs[i];
bool isNull;
Datum attr;
attr = slot_getattr(slot, attnum, &isNull);
cdbhash(hash, i + 1, attr, isNull);
}
/* End check if one tuple is in the wrong segment */
if (cdbhashreduce(hash) != GpIdentity.segindex)
{
result = false;
break;
}
}
table_endscan(scandesc);
ExecDropSingleTupleTableSlot(slot);
table_close(rel, AccessShareLock);
PG_RETURN_BOOL(result);
}
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