| From: | Andreas Pflug <pgadmin(at)pse-consulting(dot)de> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Inefficient bytea escaping? |
| Date: | 2006-05-27 11:52:52 |
| Message-ID: | 44783D94.7060004@pse-consulting.de |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> I wrote:
>
>>I'm off for a little visit with oprofile...
>
>
> It seems the answer is that fwrite() does have pretty significant
> per-call overhead, at least on Fedora Core 4. The patch I did yesterday
> still ended up making an fwrite() call every few characters when dealing
> with bytea text output, because it'd effectively do two fwrite()s per
> occurrence of '\' in the data being output. I've committed a further
> hack that buffers a whole data row before calling fwrite(). Even though
> this presumably is adding one extra level of data copying, it seems to
> make things noticeably faster:
(semi-OT) This recoding seems like a perfect preparation for a third
COPY format, compressed.
>
> Let me know what this does on your Debian machine ...
Takes a while, need a different kernel booted because the current isn't
oprofile ready.
Regards,
Andreas
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