Horton

Re: [PATCH] Transaction traceability - txid_status(bigint)

Craig Ringer <craig@2ndquadrant.com>

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From: Craig Ringer <craig@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Petr Jelinek <petr@2ndquadrant.com>, Simon Riggs <simon@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Andres Freund <andres@anarazel.de>, Jim Nasby <Jim.Nasby@bluetreble.com>, Álvaro Herrera <alvaro.herrera@2ndquadrant.com>
Date: 2017-03-20T05:38:18Z
Lists: pgsql-hackers

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On 14 March 2017 at 19:57, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Mar 13, 2017 at 10:22 PM, Craig Ringer <craig@2ndquadrant.com> wrote:
>> I'll introduce a new LWLock, ClogTruncationLock, which will be held
>> from when we advance the new clogOldestXid field through to when clog
>> truncation completes.
>
> +1.

OK, here's the revised patch. Relevant comments added where needed.

It still changes the xlog record for clog truncation to carry the new
xid, but I've left advancing oldestXid until the checkpoint as is
currently the case, and only advanced oldestClogXid when we replay
clog truncation.

-- 
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Commits

  1. Add a txid_status function.

  2. Track the oldest XID that can be safely looked up in CLOG.