Re: WAL segments (names) not in a sequence

From: German Becker <german(dot)becker(at)gmail(dot)com>
To: Amit Langote <amitlangote09(at)gmail(dot)com>
Cc: Sergey Konoplev <gray(dot)ru(at)gmail(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WAL segments (names) not in a sequence
Date: 2013-05-24 18:08:41
Message-ID: CALyjCLsAvEHrOTNtxTj6t_tRZFUbChHiwdVctH5mRja7LYny-w@mail.gmail.com
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Thanks Amit, I understand now. Is there a way to know/predict how many
prealocated segments will there be in a certain moment? What does it
deppend on?

On Fri, May 24, 2013 at 12:46 PM, Amit Langote <amitlangote09(at)gmail(dot)com>wrote:

> > I didn't quite understand what you mean by that... But anyways so do you
> > people think this sequence number overlap is "normal" ?
>
> There is "no overlap" at all. The newer segments that you see are
> "pre-allocated" ones. They have not been written to yet.
>
> From the "ls -l pg_xlog" output that you sent, it can be seen that
> segments starting from 000000010000000E000000A8 through
> 00000001000000100000007E have been pre-allocated (at that point of
> time) and 000000010000000E000000A7 is currently being written to. Just
> look at the modified times in your "ls -l" listing.
> 000000010000000E000000A7 has May 22 15:32 (the latest writes seem to
> have happened to this segment) whereas pre-allocated ones seem to have
> around May 22 12:05 to 12:15 (which are yet to be written to).
>
> Does that help?
>
> --
> Amit Langote
>

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