On Wed, May 15, 2019 at 11:54 AM Andres Freund <and...@anarazel.de> wrote:
> Attached is a prototype of a variation of this. I added a > table_tuple_tid_valid(TableScanDesc sscan, ItemPointer tid) > callback / wrapper. Currently it just takes a "plain" scan, but we could > add a separate table_beginscan variant too. > > For heap that just means we can just use HeapScanDesc's rs_nblock to > filter out invalid tids, and we only need to call > RelationGetNumberOfBlocks() once, rather than every > table_tuple_tid_valid(0 / table_get_latest_tid() call. Which is a good > improvement for nodeTidscan's table_get_latest_tid() call (for WHERE > CURRENT OF) - which previously computed the relation size once per > tuple. > Question on the patch, if not too late Why call table_beginscan() in TidNext() and not in ExecInitTidScan() ? Seems cleaner to have it in ExecInitTidScan().
