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https://git.postgresql.org/git/postgresql.git
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247 lines
6.2 KiB
C
247 lines
6.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* tid.c
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* Functions for the built-in type tuple id
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*
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* Portions Copyright (c) 1996-2002, 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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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/tid.c,v 1.31 2002/06/20 20:29:38 momjian Exp $
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*
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* NOTES
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* input routine largely stolen from boxin().
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "catalog/namespace.h"
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#include "utils/builtins.h"
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#include "catalog/pg_type.h"
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#define DatumGetItemPointer(X) ((ItemPointer) DatumGetPointer(X))
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#define ItemPointerGetDatum(X) PointerGetDatum(X)
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#define PG_GETARG_ITEMPOINTER(n) DatumGetItemPointer(PG_GETARG_DATUM(n))
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#define PG_RETURN_ITEMPOINTER(x) return ItemPointerGetDatum(x)
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#define LDELIM '('
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#define RDELIM ')'
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#define DELIM ','
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#define NTIDARGS 2
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/* ----------------------------------------------------------------
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* tidin
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* ----------------------------------------------------------------
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*/
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Datum
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tidin(PG_FUNCTION_ARGS)
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{
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char *str = PG_GETARG_CSTRING(0);
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char *p,
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*coord[NTIDARGS];
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int i;
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ItemPointer result;
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BlockNumber blockNumber;
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OffsetNumber offsetNumber;
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for (i = 0, p = str; *p && i < NTIDARGS && *p != RDELIM; p++)
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if (*p == DELIM || (*p == LDELIM && !i))
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coord[i++] = p + 1;
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if (i < NTIDARGS)
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elog(ERROR, "invalid tid format: '%s'", str);
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blockNumber = (BlockNumber) atoi(coord[0]);
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offsetNumber = (OffsetNumber) atoi(coord[1]);
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result = (ItemPointer) palloc(sizeof(ItemPointerData));
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ItemPointerSet(result, blockNumber, offsetNumber);
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PG_RETURN_ITEMPOINTER(result);
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}
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/* ----------------------------------------------------------------
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* tidout
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* ----------------------------------------------------------------
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*/
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Datum
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tidout(PG_FUNCTION_ARGS)
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{
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ItemPointer itemPtr = PG_GETARG_ITEMPOINTER(0);
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BlockId blockId;
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BlockNumber blockNumber;
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OffsetNumber offsetNumber;
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char buf[32];
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static char *invalidTid = "()";
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if (!ItemPointerIsValid(itemPtr))
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PG_RETURN_CSTRING(pstrdup(invalidTid));
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blockId = &(itemPtr->ip_blkid);
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blockNumber = BlockIdGetBlockNumber(blockId);
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offsetNumber = itemPtr->ip_posid;
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sprintf(buf, "(%d,%d)", (int) blockNumber, (int) offsetNumber);
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PG_RETURN_CSTRING(pstrdup(buf));
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}
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/*****************************************************************************
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* PUBLIC ROUTINES *
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*****************************************************************************/
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Datum
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tideq(PG_FUNCTION_ARGS)
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{
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ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
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ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
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PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) ==
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BlockIdGetBlockNumber(&(arg2->ip_blkid)) &&
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arg1->ip_posid == arg2->ip_posid);
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}
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#ifdef NOT_USED
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Datum
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tidne(PG_FUNCTION_ARGS)
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{
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ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
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ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
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PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) !=
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BlockIdGetBlockNumber(&(arg2->ip_blkid)) ||
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arg1->ip_posid != arg2->ip_posid);
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}
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#endif
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/*
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* Functions to get latest tid of a specified tuple.
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*
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* Maybe these implementations should be moved to another place
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*/
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static ItemPointerData Current_last_tid = {{0, 0}, 0};
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void
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setLastTid(const ItemPointer tid)
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{
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Current_last_tid = *tid;
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}
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/*
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* Handle CTIDs of views.
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* CTID should be defined in the view and it must
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* correspond to the CTID of a base relation.
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*/
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static Datum
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currtid_for_view(Relation viewrel, ItemPointer tid)
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{
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TupleDesc att = RelationGetDescr(viewrel);
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RuleLock *rulelock;
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RewriteRule *rewrite;
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int i, natts = att->natts, tididx = -1;
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for (i = 0; i < natts ; i++)
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{
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if (strcasecmp(NameStr(att->attrs[i]->attname), "ctid") == 0)
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{
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if (att->attrs[i]->atttypid != TIDOID)
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elog(ERROR, "ctid isn't of type TID");
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tididx = i;
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}
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}
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if (tididx < 0)
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elog(ERROR, "currtid can't handle views with no CTID");
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if (rulelock = viewrel->rd_rules, !rulelock)
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elog(ERROR, "the view has no rules");
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for (i = 0; i < rulelock->numLocks; i++)
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{
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rewrite = rulelock->rules[i];
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if (rewrite->event == CMD_SELECT)
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{
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Query *query;
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TargetEntry *tle;
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if (length(rewrite->actions) != 1)
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elog(ERROR, "only one select rule is allowed in views");
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query = (Query *) lfirst(rewrite->actions);
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tle = (TargetEntry *) nth(tididx, query->targetList);
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if (tle && tle->expr && nodeTag(tle->expr) == T_Var)
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{
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Var *var = (Var *) tle->expr;
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RangeTblEntry *rte;
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if (var->varno > 0 && var->varno < INNER && var->varattno == SelfItemPointerAttributeNumber)
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{
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rte = (RangeTblEntry *) nth(var->varno - 1, query->rtable);
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if (rte)
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{
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heap_close(viewrel, AccessShareLock);
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return DirectFunctionCall2(currtid_byreloid, ObjectIdGetDatum(rte->relid), PointerGetDatum(tid));
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}
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}
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}
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break;
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}
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}
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elog(ERROR, "currtid can't handle this view");
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return (Datum) 0;
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}
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Datum
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currtid_byreloid(PG_FUNCTION_ARGS)
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{
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Oid reloid = PG_GETARG_OID(0);
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ItemPointer tid = PG_GETARG_ITEMPOINTER(1);
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ItemPointer result;
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Relation rel;
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result = (ItemPointer) palloc(sizeof(ItemPointerData));
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if (!reloid)
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{
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*result = Current_last_tid;
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PG_RETURN_ITEMPOINTER(result);
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}
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rel = heap_open(reloid, AccessShareLock);
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if (rel->rd_rel->relkind == RELKIND_VIEW)
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return currtid_for_view(rel, tid);
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ItemPointerCopy(tid, result);
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heap_get_latest_tid(rel, SnapshotNow, result);
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heap_close(rel, AccessShareLock);
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PG_RETURN_ITEMPOINTER(result);
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}
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Datum
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currtid_byrelname(PG_FUNCTION_ARGS)
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{
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text *relname = PG_GETARG_TEXT_P(0);
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ItemPointer tid = PG_GETARG_ITEMPOINTER(1);
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ItemPointer result;
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RangeVar *relrv;
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Relation rel;
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,
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"currtid_byrelname"));
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rel = heap_openrv(relrv, AccessShareLock);
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if (rel->rd_rel->relkind == RELKIND_VIEW)
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return currtid_for_view(rel, tid);
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result = (ItemPointer) palloc(sizeof(ItemPointerData));
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ItemPointerCopy(tid, result);
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heap_get_latest_tid(rel, SnapshotNow, result);
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heap_close(rel, AccessShareLock);
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PG_RETURN_ITEMPOINTER(result);
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}
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