diff options
Diffstat (limited to 'src/backend/access/heap/heapam_handler.c')
| -rw-r--r-- | src/backend/access/heap/heapam_handler.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index 3e7a6b5548b..58de2c82a70 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -27,6 +27,7 @@ #include "access/syncscan.h" #include "access/tableam.h" #include "access/tsmapi.h" +#include "access/visibilitymap.h" #include "access/xact.h" #include "catalog/catalog.h" #include "catalog/index.h" @@ -2199,6 +2200,24 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, hscan->rs_ntuples = 0; /* + * We can skip fetching the heap page if we don't need any fields from the + * heap, the bitmap entries don't need rechecking, and all tuples on the + * page are visible to our transaction. + */ + if (!(scan->rs_flags & SO_NEED_TUPLES) && + !tbmres->recheck && + VM_ALL_VISIBLE(scan->rs_rd, tbmres->blockno, &hscan->rs_vmbuffer)) + { + /* can't be lossy in the skip_fetch case */ + Assert(tbmres->ntuples >= 0); + Assert(hscan->rs_empty_tuples_pending >= 0); + + hscan->rs_empty_tuples_pending += tbmres->ntuples; + + return true; + } + + /* * Ignore any claimed entries past what we think is the end of the * relation. It may have been extended after the start of our scan (we * only hold an AccessShareLock, and it could be inserts from this @@ -2310,6 +2329,16 @@ heapam_scan_bitmap_next_tuple(TableScanDesc scan, Page page; ItemId lp; + if (hscan->rs_empty_tuples_pending > 0) + { + /* + * If we don't have to fetch the tuple, just return nulls. + */ + ExecStoreAllNullTuple(slot); + hscan->rs_empty_tuples_pending--; + return true; + } + /* * Out of range? If so, nothing more to look at on this page */ |