Re: pg_waldump and PREPARE

On 2019-Apr-26, Fujii Masao wrote:

> Hi,
> 
> pg_waldump report no detail information about PREPARE TRANSACTION record,
> as follows.
> 
>     rmgr: Transaction len (rec/tot):    250/   250, tx:        485,
> lsn: 0/020000A8, prev 0/02000060, desc: PREPARE
> 
> I'd like to modify pg_waldump, i.e., xact_desc(), so that it reports
> detail information like GID, as follows. Attached patch does that.
> This would be helpful, for example, when diagnosing 2PC-related
> trouble by checking the status of 2PC transaction with the specified GID.
> Thought?
> 
>     rmgr: Transaction len (rec/tot):    250/   250, tx:        485,
> lsn: 0/020000A8, prev 0/02000060, desc: PREPARE gid abc: 2004-06-17
> 05:26:27.500240 JST

I think this is a great change to make.

Strangely, before your patch, ParsePrepareRecord seems completely
unused.

I'm not sure I like the moving of that routine to xactdesc.c ...
on one hand, it would be side-by-side with ParseCommitRecord, but OTOH
it seems weird to have twophase.c call xactdesc.c.  I also wonder if
defining the structs in the way you do is the most sensible arrangement.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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