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help / color / mirror / Atom feedFrom: Julien Rouhaud <[email protected]>
Subject: [PATCH v2] Allow HEAP_XMAX_LOCK_ONLY and HEAP_KEYS_UPDATED combination.
Date: Fri, 22 Jan 2021 00:06:34 +0800
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
--+HP7ph2BbKc20aGI--
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