From c87aff065c33e1a3c9bf0350f9160e84bfce1c36 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 27 Mar 2023 13:37:16 -0400
Subject: [PATCH] amcheck: Generalize one of the recently-added update chain
checks.
Commit bbc1376b39627c6bddd8a0dc0a7dda24c91a97a0 checked that if
a redirected line pointer pointed to a tuple, the tuple should be
marked both HEAP_ONLY_TUPLE and HEAP_UPDATED. But Andres Freund
pointed out that *any* tuple that is marked HEAP_ONLY_TUPLE should
be marked HEAP_UPDATED, not just one that is the target of a
redirected line pointer. Do that instead.
To see why this is better, consider a redirect line pointer A
which points to a heap-only tuple B which points (via CTID)
to another heap-only tuple C. With the old code, we'd complain
if B was not marked HEAP_UPDATED, but with this change, we'll
complain if either B or C is not marked HEAP_UPDATED.
(Note that, with or without this commit, if either B or C were
not marked HEAP_ONLY_TUPLE, we would also complain about that.)
Discussion: http://postgr.es/m/CA%2BTgmobLypZx%3DcOH%2ByY1GZmCruaoucHm77A6y_-Bo%3Dh-_3H28g%40mail.gmail.com
---
contrib/amcheck/verify_heapam.c | 20 +++++++++-----------
src/bin/pg_amcheck/t/004_verify_heapam.pl | 11 +++++------
2 files changed, 14 insertions(+), 17 deletions(-)
diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c
index 1dc9d89f306..ce3114f4e6c 100644
--- a/contrib/amcheck/verify_heapam.c
+++ b/contrib/amcheck/verify_heapam.c
@@ -624,17 +624,6 @@ verify_heapam(PG_FUNCTION_ARGS)
(unsigned) nextoffnum));
}
- /*
- * Redirects are created by updates, so successor should be
- * the result of an update.
- */
- if ((next_htup->t_infomask & HEAP_UPDATED) == 0)
- {
- report_corruption(&ctx,
- psprintf("redirected line pointer points to a non-heap-updated tuple at offset %u",
- (unsigned) nextoffnum));
- }
-
/* HOT chains should not intersect. */
if (predecessor[nextoffnum] != InvalidOffsetNumber)
{
@@ -954,6 +943,15 @@ check_tuple_header(HeapCheckContext *ctx)
*/
}
+ if (HeapTupleHeaderIsHeapOnly(tuphdr) &&
+ ((tuphdr->t_infomask & HEAP_UPDATED) == 0))
+ {
+ report_corruption(ctx,
+ psprintf("tuple is heap only, but not the result of an update"));
+
+ /* Here again, we can still perform further checks. */
+ }
+
if (infomask & HEAP_HASNULL)
expected_hoff = MAXALIGN(SizeofHeapTupleHeader + BITMAPLEN(ctx->natts));
else
diff --git a/src/bin/pg_amcheck/t/004_verify_heapam.pl b/src/bin/pg_amcheck/t/004_verify_heapam.pl
index cc4aa4af875..90ba59ec0b7 100644
--- a/src/bin/pg_amcheck/t/004_verify_heapam.pl
+++ b/src/bin/pg_amcheck/t/004_verify_heapam.pl
@@ -617,12 +617,10 @@ for (my $tupidx = 0; $tupidx < $ROWCOUNT; $tupidx++)
}
elsif ($offnum == 17)
{
- # at offnum 19 we will unset HEAP_ONLY_TUPLE and HEAP_UPDATED flags.
+ # at offnum 19 we will unset HEAP_ONLY_TUPLE flag
die "offnum $offnum should be a redirect" if defined $tup;
push @expected,
qr/${header}redirected line pointer points to a non-heap-only tuple at offset \d+/;
- push @expected,
- qr/${header}redirected line pointer points to a non-heap-updated tuple at offset \d+/;
}
elsif ($offnum == 18)
{
@@ -637,10 +635,9 @@ for (my $tupidx = 0; $tupidx < $ROWCOUNT; $tupidx++)
}
elsif ($offnum == 19)
{
- # unset HEAP_ONLY_TUPLE and HEAP_UPDATED flag, so that update chain
- # validation will complain about offset 17
+ # unset HEAP_ONLY_TUPLE flag, so that update chain validation will
+ # complain about offset 17
$tup->{t_infomask2} &= ~HEAP_ONLY_TUPLE;
- $tup->{t_infomask} &= ~HEAP_UPDATED;
}
elsif ($offnum == 22)
{
@@ -688,6 +685,8 @@ for (my $tupidx = 0; $tupidx < $ROWCOUNT; $tupidx++)
$tup->{t_infomask2} |= HEAP_ONLY_TUPLE;
push @expected,
qr/${header}tuple is root of chain but is marked as heap-only tuple/;
+ push @expected,
+ qr/${header}tuple is heap only, but not the result of an update/;
}
elsif ($offnum == 33)
{
--
2.39.5