Andres Freund <and...@2ndquadrant.com> writes: > On 2014-04-07 16:29:57 -0400, Tom Lane wrote: >> In that case you should have another tuple slot of your own and let it >> keep the tuple (and buffer pin).
> that's not going to work, because scantuple might be free'd or pointing > to another tuple, from the next index_getnext() call. Right? It's true that scantuple is probably pointing at the xs_ctup field of the IndexScanDesc, so you need to put that data somewhere else if you want to hold onto it past the current loop iteration. > So what I now do is essentially: > while ((scantuple = index_getnext(scan, ForwardScanDirection)) != NULL) > { > ... > ht = palloc(sizeof(HeapTupleData)); /* in the right context */ > memcpy(ht, scantuple, sizeof(HeapTupleData)); > ExecStoreTuple(ht, slot, scan->xs_cbuf, false); > slot->tts_shouldFree = true; > ... > } Well, that is certainly messy. I think you could just use a local HeapTupleData variable instead of palloc'ing every time, where "local" means "has lifespan similar to the slot pointer". That is HeapTupleData my_htup; while ((scantuple = index_getnext(scan, ForwardScanDirection)) != NULL) { memcpy(&my_htup, scantuple, sizeof(HeapTupleData)); ExecStoreTuple(&my_htup, slot, scan->xs_cbuf, false); } If my_htup is just a local, you'd want to clear the slot before my_htup goes out of scope, just to be sure it doesn't try to dereference a dangling pointer. There's some vaguely similar hacking near the end of ExecDelete. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers