heapam: Track heap block in IndexFetchHeapData. Add an explicit BlockNumber field (xs_blk) to IndexFetchHeapData that tracks which heap block is currently pinned in xs_cbuf.
heapam_index_fetch_tuple now uses xs_blk to determine when buffer switching is needed, replacing the previous approach that compared buffer identities via ReleaseAndReadBuffer on every non-HOT-chain call. This is preparatory work for an upcoming commit that will add index prefetching using a read stream. Delegating the release of a currently pinned buffer to ReleaseAndReadBuffer won't work anymore -- at least not when the next buffer that the scan needs to pin is one returned by read_stream_next_buffer (not a buffer returned by ReadBuffer). Author: Peter Geoghegan <[email protected]> Reviewed-By: Andres Freund <[email protected]> Discussion: https://postgr.es/m/CAH2-Wz=g=jtsydb4utb5su2zcvss7vbp+zmvvag6abocb+s...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/c7d09595e46ff513ae0a23ae80e58871a321174f Modified Files -------------- src/backend/access/heap/heapam_indexscan.c | 31 ++++++++++++++++++------------ src/include/access/heapam.h | 5 +++-- 2 files changed, 22 insertions(+), 14 deletions(-)
