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| author | Thomas Munro <tmunro@postgresql.org> | 2023-09-05 18:26:12 +1200 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2023-09-05 19:53:43 +1200 |
| commit | f691f5b80a85c66d715b4340ffabb503eb19393e (patch) | |
| tree | 26a06c87096de2f9571956b4370ccbf1852d4cba /src/backend/access/heap/heapam.c | |
| parent | aa0d3504560d40f4300a3d49d1c6c3bfc3b894e5 (diff) | |
| download | postgresql-f691f5b80a85c66d715b4340ffabb503eb19393e.tar.gz postgresql-f691f5b80a85c66d715b4340ffabb503eb19393e.zip | |
Remove the "snapshot too old" feature.
Remove the old_snapshot_threshold setting and mechanism for producing
the error "snapshot too old", originally added by commit 848ef42b.
Unfortunately it had a number of known problems in terms of correctness
and performance, mostly reported by Andres in the course of his work on
snapshot scalability. We agreed to remove it, after a long period
without an active plan to fix it.
This is certainly a desirable feature, and someone might propose a new
or improved implementation in the future.
Reported-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CACG%3DezYV%2BEvO135fLRdVn-ZusfVsTY6cH1OZqWtezuEYH6ciQA%40mail.gmail.com
Discussion: https://postgr.es/m/20200401064008.qob7bfnnbu4w5cw4%40alap3.anarazel.de
Discussion: https://postgr.es/m/CA%2BTgmoY%3Daqf0zjTD%2B3dUWYkgMiNDegDLFjo%2B6ze%3DWtpik%2B3XqA%40mail.gmail.com
Diffstat (limited to 'src/backend/access/heap/heapam.c')
| -rw-r--r-- | src/backend/access/heap/heapam.c | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index dc3c4074ed6..88a123d38a6 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -425,7 +425,6 @@ heapgetpage(TableScanDesc sscan, BlockNumber block) LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, page); lines = PageGetMaxOffsetNumber(page); ntup = 0; @@ -565,8 +564,6 @@ heapgettup_start_page(HeapScanDesc scan, ScanDirection dir, int *linesleft, /* Caller is responsible for ensuring buffer is locked if needed */ page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); - *linesleft = PageGetMaxOffsetNumber(page) - FirstOffsetNumber + 1; if (ScanDirectionIsForward(dir)) @@ -598,8 +595,6 @@ heapgettup_continue_page(HeapScanDesc scan, ScanDirection dir, int *linesleft, /* Caller is responsible for ensuring buffer is locked if needed */ page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); - if (ScanDirectionIsForward(dir)) { *lineoff = OffsetNumberNext(scan->rs_coffset); @@ -864,7 +859,6 @@ heapgettup_pagemode(HeapScanDesc scan, /* continue from previously returned page/tuple */ block = scan->rs_cblock; /* current page */ page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); lineindex = scan->rs_cindex + dir; if (ScanDirectionIsForward(dir)) @@ -884,7 +878,6 @@ heapgettup_pagemode(HeapScanDesc scan, { heapgetpage((TableScanDesc) scan, block); page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); linesleft = scan->rs_ntuples; lineindex = ScanDirectionIsForward(dir) ? 0 : linesleft - 1; @@ -1372,7 +1365,6 @@ heap_fetch(Relation relation, */ LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, relation, page); /* * We'd better check for out-of-range offnum in case of VACUUM since the @@ -1663,7 +1655,6 @@ heap_get_latest_tid(TableScanDesc sscan, buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid)); LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, relation, page); /* * Check for bogus item number. This is not treated as an error |