BitmapHeapScan: Use correct recheck flag for skip_fetch As of 7c70996ebf0949b142a9, BitmapPrefetch() used the recheck flag for the current block to determine whether or not it should skip prefetching the proposed prefetch block. As explained in the comment, this assumed the index AM will report the same recheck value for the future page as it did for the current page - but there's no guarantee.
This only affects prefetching - if the recheck flag changes, we may prefetch blocks unecessarily and not prefetch blocks that will be needed. But we don't need to rely on that assumption - we know the recheck flag for the block we're considering prefetching, so we can use that. The impact is very limited in practice - the opclass would need to assign different recheck flags to different blocks, but none of the built-in opclasses seems to do that. Author: Melanie Plageman Reviewed-by: Tomas Vondra, Andres Freund, Tom Lane Discussion: https://postgr.es/m/1939305.1712415547%40sss.pgh.pa.us Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/1fdb0ce9b10970a4b02f1ef0c269e2c1fbbecd25 Modified Files -------------- src/backend/executor/nodeBitmapHeapscan.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-)
