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Repair CLUSTER failure after ALTER TABLE SET WITHOUT OIDS. Turns out

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there are corner cases involving dropping toasted columns in which the
previous coding would fail, too: the new version of the table might not
have any TOAST table, but we'd still propagate possibly-wide values of
dropped columns forward.
This commit is contained in:
Tom Lane 2005-02-06 20:19:08 +00:00
parent 4f82112473
commit 2a6c032503
1 changed files with 62 additions and 11 deletions
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73
src/backend/commands/cluster.c
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@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.131 2004/12/31 21:59:41 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.132 2005/02/06 20:19:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -605,32 +605,80 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex)
Relation NewHeap,
OldHeap,
OldIndex;
TupleDesc oldTupDesc;
TupleDesc newTupDesc;
int natts;
Datum *values;
char *nulls;
IndexScanDesc scan;
HeapTuple tuple;
/*
* Open the relations I need. Scan through the OldHeap on the OldIndex
* and insert each tuple into the NewHeap.
* Open the relations we need.
*/
NewHeap = heap_open(OIDNewHeap, AccessExclusiveLock);
OldHeap = heap_open(OIDOldHeap, AccessExclusiveLock);
OldIndex = index_open(OIDOldIndex);
/*
* Their tuple descriptors should be exactly alike, but here we only
* need assume that they have the same number of columns.
*/
oldTupDesc = RelationGetDescr(OldHeap);
newTupDesc = RelationGetDescr(NewHeap);
Assert(newTupDesc->natts == oldTupDesc->natts);
/* Preallocate values/nulls arrays */
natts = newTupDesc->natts;
values = (Datum *) palloc0(natts * sizeof(Datum));
nulls = (char *) palloc(natts * sizeof(char));
memset(nulls, 'n', natts * sizeof(char));
/*
* Scan through the OldHeap on the OldIndex and copy each tuple into the
* NewHeap.
*/
scan = index_beginscan(OldHeap, OldIndex, SnapshotNow, 0, (ScanKey) NULL);
while ((tuple = index_getnext(scan, ForwardScanDirection)) != NULL)
{
/*
* We must copy the tuple because heap_insert() will overwrite the
* commit-status fields of the tuple it's handed, and the
* retrieved tuple will actually be in a disk buffer! Thus, the
* source relation would get trashed, which is bad news if we
* abort later on. (This was a bug in releases thru 7.0)
* We cannot simply pass the tuple to heap_insert(), for several
* reasons:
*
* Note that the copied tuple will have the original OID, if any, so
* this does preserve OIDs.
* 1. heap_insert() will overwrite the commit-status fields of the
* tuple it's handed. This would trash the source relation, which is
* bad news if we abort later on. (This was a bug in releases thru
* 7.0)
*
* 2. We'd like to squeeze out the values of any dropped columns,
* both to save space and to ensure we have no corner-case failures.
* (It's possible for example that the new table hasn't got a TOAST
* table and so is unable to store any large values of dropped cols.)
*
* 3. The tuple might not even be legal for the new table; this is
* currently only known to happen as an after-effect of ALTER TABLE
* SET WITHOUT OIDS.
*
* So, we must reconstruct the tuple from component Datums.
*/
HeapTuple copiedTuple = heap_copytuple(tuple);
HeapTuple copiedTuple;
int i;
heap_deformtuple(tuple, oldTupDesc, values, nulls);
/* Be sure to null out any dropped columns */
for (i = 0; i < natts; i++)
{
if (newTupDesc->attrs[i]->attisdropped)
nulls[i] = 'n';
}
copiedTuple = heap_formtuple(newTupDesc, values, nulls);
/* Preserve OID, if any */
if (NewHeap->rd_rel->relhasoids)
HeapTupleSetOid(copiedTuple, HeapTupleGetOid(tuple));
simple_heap_insert(NewHeap, copiedTuple);
@ -641,6 +689,9 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex)
index_endscan(scan);
pfree(values);
pfree(nulls);
index_close(OldIndex);
heap_close(OldHeap, NoLock);
heap_close(NewHeap, NoLock);