diff options
Diffstat (limited to 'src/backend/access/heap/heapam.c')
| -rw-r--r-- | src/backend/access/heap/heapam.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 86a2e6bae6a..6f4ff2718fe 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -277,7 +277,6 @@ initscan(HeapScanDesc scan, ScanKey key, bool is_rescan) scan->rs_startblock = 0; } - scan->rs_initblock = 0; scan->rs_numblocks = InvalidBlockNumber; scan->rs_inited = false; scan->rs_ctup.t_data = NULL; @@ -302,11 +301,22 @@ initscan(HeapScanDesc scan, ScanKey key, bool is_rescan) pgstat_count_heap_scan(scan->rs_rd); } +/* + * heap_setscanlimits - restrict range of a heapscan + * + * startBlk is the page to start at + * numBlks is number of pages to scan (InvalidBlockNumber means "all") + */ void heap_setscanlimits(HeapScanDesc scan, BlockNumber startBlk, BlockNumber numBlks) { + Assert(!scan->rs_inited); /* else too late to change */ + Assert(!scan->rs_syncscan); /* else rs_startblock is significant */ + + /* Check startBlk is valid (but allow case of zero blocks...) */ + Assert(startBlk == 0 || startBlk < scan->rs_nblocks); + scan->rs_startblock = startBlk; - scan->rs_initblock = startBlk; scan->rs_numblocks = numBlks; } @@ -477,7 +487,7 @@ heapgettup(HeapScanDesc scan, /* * return null immediately if relation is empty */ - if (scan->rs_nblocks == 0) + if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; @@ -511,7 +521,7 @@ heapgettup(HeapScanDesc scan, /* * return null immediately if relation is empty */ - if (scan->rs_nblocks == 0) + if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; @@ -651,7 +661,7 @@ heapgettup(HeapScanDesc scan, if (backward) { finished = (page == scan->rs_startblock) || - (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks <= 0 : false); + (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false); if (page == 0) page = scan->rs_nblocks; page--; @@ -662,7 +672,7 @@ heapgettup(HeapScanDesc scan, if (page >= scan->rs_nblocks) page = 0; finished = (page == scan->rs_startblock) || - (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks <= 0 : false); + (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false); /* * Report our new scan position for synchronization purposes. We @@ -754,7 +764,7 @@ heapgettup_pagemode(HeapScanDesc scan, /* * return null immediately if relation is empty */ - if (scan->rs_nblocks == 0) + if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; @@ -785,7 +795,7 @@ heapgettup_pagemode(HeapScanDesc scan, /* * return null immediately if relation is empty */ - if (scan->rs_nblocks == 0) + if (scan->rs_nblocks == 0 || scan->rs_numblocks == 0) { Assert(!BufferIsValid(scan->rs_cbuf)); tuple->t_data = NULL; @@ -914,7 +924,7 @@ heapgettup_pagemode(HeapScanDesc scan, if (backward) { finished = (page == scan->rs_startblock) || - (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks <= 0 : false); + (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false); if (page == 0) page = scan->rs_nblocks; page--; @@ -925,7 +935,7 @@ heapgettup_pagemode(HeapScanDesc scan, if (page >= scan->rs_nblocks) page = 0; finished = (page == scan->rs_startblock) || - (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks <= 0 : false); + (scan->rs_numblocks != InvalidBlockNumber ? --scan->rs_numblocks == 0 : false); /* * Report our new scan position for synchronization purposes. We |