amcheck: Fix snapshot usage in bt_index_parent_check

We were using SnapshotAny to do some index checks, but that's wrong and
causes spurious errors when used on indexes created by CREATE INDEX
CONCURRENTLY.  Fix it to use an MVCC snapshot, and add a test for it.

Backpatch of 6bd469d26aca to branches 14-16.  I previously misidentified
the bug's origin: it came in with commit 7f563c09f890 (pg11-era, not
5ae2087202af as claimed previously), so all live branches are affected.

Also take the opportunity to fix some comments that we failed to update
in the original commits and apply pgperltidy.  In branch 14, remove the
unnecessary test plan specification (which would have need to have been
changed anyway; c.f. commit 549ec201d613.)

Diagnosed-by: Donghang Lin <donghanglin@gmail.com>
Author: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Reviewed-by: Andrey Borodin <x4mmm@yandex-team.ru>
Backpatch-through: 17
Discussion: https://postgr.es/m/CANtu0ojmVd27fEhfpST7RG2KZvwkX=dMyKUqg0KM87FkOSdz8Q@mail.gmail.com

diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
index eb41f3bea7cb67d25518e83d8ede7bc5a49b31c3..b49acb2b9ef2ebe74d8e4ddbf594048fe3d65bac 100644 (file)
--- a/contrib/amcheck/t/002_cic.pl
+++ b/contrib/amcheck/t/002_cic.pl
@@ -74,7 +74,8 @@ $in_progress_h->query_safe(q(BEGIN; SELECT pg_current_xact_id();));
 # delete one row from table, while background transaction is in progress
 $node->safe_psql('postgres', q(DELETE FROM quebec WHERE i = 1;));
 # create index concurrently, which will skip the deleted row
-$node->safe_psql('postgres', q(CREATE INDEX CONCURRENTLY oscar ON quebec(i);));
+$node->safe_psql('postgres',
+       q(CREATE INDEX CONCURRENTLY oscar ON quebec(i);));
 
 # check index using bt_index_parent_check
 $result = $node->psql('postgres',

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 32648c6c6d0e97bb79fb784579221be39482ab46..120f02cf23723bdee8efa579dc1e9cae1326ffc3 100644 (file)
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -90,9 +90,11 @@ typedef struct BtreeCheckState
        BufferAccessStrategy checkstrategy;
 
        /*
-        * Info for uniqueness checking. Fill these fields once per index check.
+        * Info for uniqueness checking. Fill this field and the one below once
+        * per index check.
         */
        IndexInfo  *indexinfo;
+       /* Table scan snapshot for heapallindexed and checkunique */
        Snapshot        snapshot;
 
        /*