Re: Inserting 8MB bytea: just 25% of disk perf used?

From: "fkater(at)googlemail(dot)com" <fkater(at)googlemail(dot)com>
To: Matthew Wakeling <matthew(at)flymine(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Inserting 8MB bytea: just 25% of disk perf used?
Date: 2010-01-18 16:13:15
Message-ID: 20100118161315.GG2913@comppasch2
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Matthew Wakeling:

> The data needs to be written first to the WAL, in order to provide
> crash-safety. So you're actually writing 1600MB, not 800.

I come back again to saving WAL to another disk. Now, after
all, I wonder: Doesn't the server wait anyway until WAL was
written to disk?

So, if true, does it should not really matter if WAL is
written to another disk then or not (besides some savings by
2x hd cache and less hd head moves).

Felix

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