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Make DROP TABLE rollback-able: postpone physical file delete until commit.

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(WAL logging for this is not done yet, however.)  Clean up a number of really
crufty things that are no longer needed now that DROP behaves nicely.  Make
temp table mapper do the right things when drop or rename affecting a temp
table is rolled back.  Also, remove "relation modified while in use" error
check, in favor of locking tables at first reference and holding that lock
throughout the statement.
This commit is contained in:
Tom Lane
2000-11-08 22:10:03 +00:00
parent ebe0b23690
commit 3908473c80
46 changed files with 1305 additions and 1187 deletions
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61
src/backend/parser/parse_relation.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.49 2000/09/29 18:21:36 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_relation.c,v 1.50 2000/11/08 22:09:58 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -34,6 +34,7 @@ static Node *scanRTEForColumn(ParseState *pstate, RangeTblEntry *rte,
char *colname);
static Node *scanJoinForColumn(JoinExpr *join, char *colname,
int sublevels_up);
static bool isForUpdate(ParseState *pstate, char *relname);
static List *expandNamesVars(ParseState *pstate, List *names, List *vars);
static void warnAutoRange(ParseState *pstate, char *refname);
@ -477,6 +478,7 @@ addRangeTableEntry(ParseState *pstate,
bool inFromCl)
{
char *refname = alias ? alias->relname : relname;
LOCKMODE lockmode;
Relation rel;
RangeTblEntry *rte;
Attr *eref;
@ -502,17 +504,22 @@ addRangeTableEntry(ParseState *pstate,
/*
* Get the rel's OID. This access also ensures that we have an
* up-to-date relcache entry for the rel. We don't need to keep it
* open, however. Since this is open anyway, let's check that the
* number of column aliases is reasonable. - Thomas 2000-02-04
* up-to-date relcache entry for the rel. Since this is typically
* the first access to a rel in a statement, be careful to get the
* right access level depending on whether we're doing SELECT FOR UPDATE.
*/
rel = heap_openr(relname, AccessShareLock);
lockmode = isForUpdate(pstate, relname) ? RowShareLock : AccessShareLock;
rel = heap_openr(relname, lockmode);
rte->relid = RelationGetRelid(rel);
maxattrs = RelationGetNumberOfAttributes(rel);
eref = alias ? (Attr *) copyObject(alias) : makeAttr(refname, NULL);
numaliases = length(eref->attrs);
/*
* Since the rel is open anyway, let's check that the
* number of column aliases is reasonable. - Thomas 2000-02-04
*/
maxattrs = RelationGetNumberOfAttributes(rel);
if (maxattrs < numaliases)
elog(ERROR, "Table \"%s\" has %d columns available but %d columns specified",
refname, maxattrs, numaliases);
@ -527,7 +534,12 @@ addRangeTableEntry(ParseState *pstate,
}
rte->eref = eref;
heap_close(rel, AccessShareLock);
/*
* Drop the rel refcount, but keep the access lock till end of transaction
* so that the table can't be deleted or have its schema modified
* underneath us.
*/
heap_close(rel, NoLock);
/*----------
* Flags:
@ -643,6 +655,41 @@ addRangeTableEntryForSubquery(ParseState *pstate,
return rte;
}
/*
* Has the specified relname been selected FOR UPDATE?
*/
static bool
isForUpdate(ParseState *pstate, char *relname)
{
/* Outer loop to check parent query levels as well as this one */
while (pstate != NULL)
{
if (pstate->p_forUpdate != NIL)
{
if (lfirst(pstate->p_forUpdate) == NULL)
{
/* all tables used in query */
return true;
}
else
{
/* just the named tables */
List *l;
foreach(l, pstate->p_forUpdate)
{
char *rname = lfirst(l);
if (strcmp(relname, rname) == 0)
return true;
}
}
}
pstate = pstate->parentParseState;
}
return false;
}
/*
* Add the given RTE as a top-level entry in the pstate's join list,
* unless there already is an entry for it.