On Thu, Feb 04, 2021 at 08:34:13PM +0530, Mahendra Singh Thalor wrote: > On Tue, 2 Feb 2021 at 09:51, Julien Rouhaud <rjuju...@gmail.com> wrote: > > > > On Mon, Feb 01, 2021 at 02:00:48PM -0300, Alvaro Herrera wrote: > > > So I think that I misspoke earlier in this thread when I said this is a > > > bug, and that the right fix here is to remove the Assert() and change > > > amcheck to match. > > > > I'm attaching a patch to do so. > > Thanks Julien for the patch. > > Patch looks good to me and it is fixing the problem. I think we can > register in CF.
Thanks for looking at it! I just created an entry for the next commitfest. > > > > Changing the name may be overkill, but claryfing the hint bit usage in > > README.tuplock would definitely be useful, especially since the combination > > isn't always produced. How about adding something like: > > > > HEAP_KEYS_UPDATED > > This bit lives in t_infomask2. If set, indicates that the XMAX updated > > this tuple and changed the key values, or it deleted the tuple. > > + It can also be set in combination of HEAP_XMAX_LOCK_ONLY. > > It's set regardless of whether the XMAX is a TransactionId or a > > MultiXactId. > Make sense. Please can you update this? Sure, done in attached v2!
>From d74c216d8817659237f26baec789c6b79d337296 Mon Sep 17 00:00:00 2001 From: Julien Rouhaud <julien.rouh...@free.fr> Date: Fri, 22 Jan 2021 00:06:34 +0800 Subject: [PATCH v2] Allow HEAP_XMAX_LOCK_ONLY and HEAP_KEYS_UPDATED combination. This combination of hint bits was previously detected as a form of corruption, but it can be obtained with some mix of SELECT ... FOR UPDATE and UPDATE queries. Discussion: https://postgr.es/m/20210124061758.GA11756@nol --- contrib/amcheck/t/001_verify_heapam.pl | 14 +++++++++++++- contrib/amcheck/verify_heapam.c | 7 ------- src/backend/access/heap/README.tuplock | 5 +++-- src/backend/access/heap/hio.c | 8 +++----- 4 files changed, 19 insertions(+), 15 deletions(-) diff --git a/contrib/amcheck/t/001_verify_heapam.pl b/contrib/amcheck/t/001_verify_heapam.pl index a2f65b826d..6050feb712 100644 --- a/contrib/amcheck/t/001_verify_heapam.pl +++ b/contrib/amcheck/t/001_verify_heapam.pl @@ -4,7 +4,7 @@ use warnings; use PostgresNode; use TestLib; -use Test::More tests => 79; +use Test::More tests => 80; my ($node, $result); @@ -47,6 +47,9 @@ detects_heap_corruption( # fresh_test_table('test'); $node->safe_psql('postgres', q(VACUUM (FREEZE, DISABLE_PAGE_SKIPPING) test)); +detects_no_corruption( + "verify_heapam('test')", + "all-frozen not corrupted table"); corrupt_first_page('test'); detects_heap_corruption("verify_heapam('test')", "all-frozen corrupted table"); @@ -92,6 +95,15 @@ sub fresh_test_table ALTER TABLE $relname ALTER b SET STORAGE external; INSERT INTO $relname (a, b) (SELECT gs, repeat('b',gs*10) FROM generate_series(1,1000) gs); + BEGIN; + SAVEPOINT s1; + SELECT 1 FROM $relname WHERE a = 42 FOR UPDATE; + UPDATE $relname SET b = b WHERE a = 42; + RELEASE s1; + SAVEPOINT s1; + SELECT 1 FROM $relname WHERE a = 42 FOR UPDATE; + UPDATE $relname SET b = b WHERE a = 42; + COMMIT; )); } diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c index 88ab32490c..49f5ca0ef2 100644 --- a/contrib/amcheck/verify_heapam.c +++ b/contrib/amcheck/verify_heapam.c @@ -608,13 +608,6 @@ check_tuple_header_and_visibilty(HeapTupleHeader tuphdr, HeapCheckContext *ctx) ctx->tuphdr->t_hoff, ctx->lp_len)); header_garbled = true; } - if ((ctx->tuphdr->t_infomask & HEAP_XMAX_LOCK_ONLY) && - (ctx->tuphdr->t_infomask2 & HEAP_KEYS_UPDATED)) - { - report_corruption(ctx, - pstrdup("tuple is marked as only locked, but also claims key columns were updated")); - header_garbled = true; - } if ((ctx->tuphdr->t_infomask & HEAP_XMAX_COMMITTED) && (ctx->tuphdr->t_infomask & HEAP_XMAX_IS_MULTI)) diff --git a/src/backend/access/heap/README.tuplock b/src/backend/access/heap/README.tuplock index d03ddf6cdc..6d357565a8 100644 --- a/src/backend/access/heap/README.tuplock +++ b/src/backend/access/heap/README.tuplock @@ -147,8 +147,9 @@ The following infomask bits are applicable: - HEAP_KEYS_UPDATED This bit lives in t_infomask2. If set, indicates that the XMAX updated - this tuple and changed the key values, or it deleted the tuple. - It's set regardless of whether the XMAX is a TransactionId or a MultiXactId. + this tuple and changed the key values, or it deleted the tuple. It can also + be set in combination of HEAP_XMAX_LOCK_ONLY. It's set regardless of whether + the XMAX is a TransactionId or a MultiXactId. We currently never set the HEAP_XMAX_COMMITTED when the HEAP_XMAX_IS_MULTI bit is set. diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c index fb7ad0bab4..75223c9bea 100644 --- a/src/backend/access/heap/hio.c +++ b/src/backend/access/heap/hio.c @@ -49,12 +49,10 @@ RelationPutHeapTuple(Relation relation, /* * Do not allow tuples with invalid combinations of hint bits to be placed - * on a page. These combinations are detected as corruption by the - * contrib/amcheck logic, so if you disable one or both of these - * assertions, make corresponding changes there. + * on a page. This combination is detected as corruption by the + * contrib/amcheck logic, so if you disable this assertion, make + * corresponding changes there. */ - Assert(!((tuple->t_data->t_infomask & HEAP_XMAX_LOCK_ONLY) && - (tuple->t_data->t_infomask2 & HEAP_KEYS_UPDATED))); Assert(!((tuple->t_data->t_infomask & HEAP_XMAX_COMMITTED) && (tuple->t_data->t_infomask & HEAP_XMAX_IS_MULTI))); -- 2.20.1
