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help / color / mirror / Atom feedFrom: Tom Lane <[email protected]>
To: Heikki Linnakangas <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Ashutosh Bapat <[email protected]>
Cc: Maxim Orlov <[email protected]>
Cc: Alexander Korotkov <[email protected]>
Cc: wenhui qiu <[email protected]>
Cc: Postgres hackers <[email protected]>
Subject: Re: POC: make mxidoff 64 bits
Date: Sun, 14 Dec 2025 17:55:36 -0500
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
<[email protected]>
Heikki Linnakangas <[email protected]> writes:
> Ok, I have pushed this. Thanks!
Coverity is unhappy about this bit:
/srv/coverity/git/pgsql-git/postgresql/src/bin/pg_upgrade/multixact_read_v18.c: 282 in GetOldMultiXactIdSingleMember()
276 if (!TransactionIdIsValid(*xactptr))
277 {
278 /*
279 * Corner case 2: we are looking at unused slot zero
280 */
281 if (offset == 0)
>>> CID 1676077: Control flow issues (DEADCODE)
>>> Execution cannot reach this statement: "continue;".
282 continue;
283
284 /*
285 * Otherwise this is an invalid entry that should not be
It sees the earlier test for offset == 0, and evidently is assuming
that the loop's "offset++" will not wrap around. Now I think that
the point of this check is exactly that "offset++" could have wrapped
around, but the commentary is not so clear that I'm certain this is a
false positive. If that is the intention, what do you think of
rephrasing this comment as "we have wrapped around to unused slot
zero"?
regards, tom lane
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