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CREATE VIEW as SELECT CTID, ....
  SELECT currtid( a view, ..).
This commit is contained in:
Hiroshi Inoue
2002-05-22 07:46:58 +00:00
parent 79420840ee
commit a3519a2fcc
2 changed files with 99 additions and 33 deletions
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66
src/backend/utils/adt/tid.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/tid.c,v 1.29 2002/03/30 01:02:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/tid.c,v 1.30 2002/05/22 07:46:58 inoue Exp $
*
* NOTES
* input routine largely stolen from boxin().
@ -21,6 +21,7 @@
#include "access/heapam.h"
#include "catalog/namespace.h"
#include "utils/builtins.h"
#include "catalog/pg_type.h"
#define DatumGetItemPointer(X) ((ItemPointer) DatumGetPointer(X))
#define ItemPointerGetDatum(X) PointerGetDatum(X)
@ -133,6 +134,65 @@ setLastTid(const ItemPointer tid)
Current_last_tid = *tid;
}
/*
* Handle CTIDs of views.
* CTID should be defined in the view and it must
* correspond to the CTID of a base relation.
*/
static Datum
currtid_for_view(Relation viewrel, ItemPointer tid)
{
TupleDesc att = RelationGetDescr(viewrel);
RuleLock *rulelock;
RewriteRule *rewrite;
int i, natts = att->natts, tididx = -1;
for (i = 0; i < natts ; i++)
{
if (strcasecmp(NameStr(att->attrs[i]->attname), "ctid") == 0)
{
if (att->attrs[i]->atttypid != TIDOID)
elog(ERROR, "ctid isn't of type TID");
tididx = i;
}
}
if (tididx < 0)
elog(ERROR, "currtid can't handle views with no CTID");
if (rulelock = viewrel->rd_rules, !rulelock)
elog(ERROR, "the view has no rules");
for (i = 0; i < rulelock->numLocks; i++)
{
rewrite = rulelock->rules[i];
if (rewrite->event == CMD_SELECT)
{
Query *query;
TargetEntry *tle;
if (length(rewrite->actions) != 1)
elog(ERROR, "only one select rule is allowed in views");
query = (Query *) lfirst(rewrite->actions);
tle = (TargetEntry *) nth(tididx, query->targetList);
if (tle && tle->expr && nodeTag(tle->expr) == T_Var)
{
Var *var = (Var *) tle->expr;
RangeTblEntry *rte;
if (var->varno > 0 && var->varno < INNER && var->varattno == SelfItemPointerAttributeNumber)
{
rte = (RangeTblEntry *) nth(var->varno - 1, query->rtable);
if (rte)
{
heap_close(viewrel, AccessShareLock);
return DirectFunctionCall2(currtid_byreloid, ObjectIdGetDatum(rte->relid), PointerGetDatum(tid));
}
}
}
break;
}
}
elog(ERROR, "currtid can't handle this view");
return (Datum) 0;
}
Datum
currtid_byreloid(PG_FUNCTION_ARGS)
{
@ -149,6 +209,8 @@ currtid_byreloid(PG_FUNCTION_ARGS)
}
rel = heap_open(reloid, AccessShareLock);
if (rel->rd_rel->relkind == RELKIND_VIEW)
return currtid_for_view(rel, tid);
ItemPointerCopy(tid, result);
heap_get_latest_tid(rel, SnapshotNow, result);
@ -170,6 +232,8 @@ currtid_byrelname(PG_FUNCTION_ARGS)
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,
"currtid_byrelname"));
rel = heap_openrv(relrv, AccessShareLock);
if (rel->rd_rel->relkind == RELKIND_VIEW)
return currtid_for_view(rel, tid);
result = (ItemPointer) palloc(sizeof(ItemPointerData));
ItemPointerCopy(tid, result);