Re: 9.4.1 -> 9.4.2 problem: could not access status of transaction 1

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Noah Misch <noah(at)leadboat(dot)com>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, Steve Kehlet <steve(dot)kehlet(at)gmail(dot)com>, Forums postgresql <pgsql-general(at)postgresql(dot)org>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 9.4.1 -> 9.4.2 problem: could not access status of transaction 1
Date: 2015-06-04 16:57:42
Message-ID: CA+TgmoZxY=HUxnQPUyEtdzgMw386j55-CjRKUUcbFiqJcwSv8g@mail.gmail.com
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On Thu, Jun 4, 2015 at 9:42 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> Thanks for the review.

Here's a new version. I've fixed the things Alvaro and Noah noted,
and some compiler warnings about set but unused variables.

I also tested it, and it doesn't quite work as hoped. If started on a
cluster where oldestMultiXid is incorrectly set to 1, it starts up and
indicates that the member wraparound guards are disabled. But even
after everything is fixed, they don't get enabled until after the next
full restart. I think that's because TruncateMultiXact() bails out
too early, without calling DetermineSafeOldestOffset.

My attempt at a quick fix for that problem didn't work out, so I'm
posting this version for now to facilitate further review and testing.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Attachment Content-Type Size
multixact-member-soft-fail-v2-93.patch application/x-patch 17.3 KB
multixact-member-soft-fail-v2.patch application/x-patch 17.1 KB

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