MIME-Version: 1.0
References: <432626F9-65DF-4F0D-B345-26CFC3E2CFAC@yandex-team.ru>
 <CAN4CZFNCyEOC8exfEn9SVV=uhzUA4KQYcVRUea2E0ts-rvXg3w@mail.gmail.com>
 <A355EB21-614C-43A9-85A0-D4822DC13B04@yandex-team.ru>
 <9A5AEB25-5E58-4657-9064-7D4F8D50A77D@yandex-team.ru>
In-Reply-To: <9A5AEB25-5E58-4657-9064-7D4F8D50A77D@yandex-team.ru>
From: Zsolt Parragi <zsolt.parragi@percona.com>
Date: Mon, 2 Mar 2026 23:19:22 +0000
Message-ID: 
 <CAN4CZFNdvMqgHpB04SSqDjv1Z5g3Dv2Z6Uyb4P5dDo6p04Z=Kg@mail.gmail.com>
Subject: Re: amcheck: add index-all-keys-match verification for B-Tree
To: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Archived-At: 
 <https://www.postgresql.org/message-id/CAN4CZFNdvMqgHpB04SSqDjv1Z5g3Dv2Z6Uyb4P5dDo6p04Z%3DKg%40mail.gmail.com>
Precedence: bulk

I don't see any other logic problems in the code, I only have a few
minor comments/questions:

+ * Bloom filter says (key, tid) not in heap.  Follow TID to verify; this
+ * amortizes random heap lookups when the filter has false negatives, or

This comment could be a bit confusing, as bloom filters typically have
false positives, not negatives.
Maybe it would be better to phrase this somehow differently?

Another thing is that now amcheck can create two bloom filters,
allocated at the same time, both up to maintenance_work_mem.
Isn't that a detail that should be at least mentioned somewhere?

And in the documentation, shouldn't this new check mention something
similar to heapallindexed, which describes the check possibly missing
corruption because of the bloom filter?

+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("index tuple in index \"%s\" does not match heap tuple",
+ RelationGetRelationName(state->rel)),

Shouldn't this also print out the table name?