Re: WAL does not recover gracefully from out-of-disk-sp ace

From: Ian Lance Taylor <ian(at)airs(dot)com>
To: "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: WAL does not recover gracefully from out-of-disk-sp ace
Date: 2001-03-08 18:51:38
Message-ID: sivgpkf611.fsf@daffy.airs.com
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"Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM> writes:

> > But we need it regardless --- if you didn't want a fully-allocated WAL
> > file, why'd you bother with the original seek-and-write-1-byte code?
>
> I considered this mostly as hint for OS about how log file should be
> allocated (to decrease fragmentation). Not sure how OSes use such hints
> but seek+write costs nothing.

Doing a seek to a large value and doing a write is not a hint to a
Unix system that you are going to write a large sequential file. If
anything, it's a hint that you are going to write a sparse file. A
Unix kernel will optimize by not allocating blocks you aren't going to
write to.

Ian

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