Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, PostgreSQL Win32 port list <pgsql-hackers-win32(at)postgresql(dot)org>
Subject: Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint
Date: 2004-01-30 17:13:55
Message-ID: 15426.1075482835@sss.pgh.pa.us
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Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> The trick is to somehow record all files modified since the last
> checkpoint, and open/fsync/close each one. My idea is to stat() each
> file in each directory and compare the modify time to determine if the
> file has been modified since the last checkpoint.

This seems a complete non-starter, as stat() generally has at best
one-second resolution on mod times, even if you assume that the kernel
keeps mod time fully up-to-date at all times. In any case, it's
difficult to believe that stat'ing everything in a database directory
will be faster than keeping track of it for ourselves.

regards, tom lane

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