| From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Scaling XLog insertion (was Re: Moving more work outside WALInsertLock) |
| Date: | 2012-03-07 07:07:37 |
| Message-ID: | CAHGQGwFUMW-8eGjAVOQEhEem16RYD6WRLF4H_EXHZwdCn=V-ow@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Mar 7, 2012 at 5:32 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> What I suggest is that it should not be necessary to crawl forward one
> page at a time to figure out how many pages will be needed to store N
> bytes worth of WAL data. You're basically implementing a division
> problem as repeated subtraction. Getting the extra WAL-segment-start
> overhead right would be slightly tricky; but even if you didn't want to
> try to make it pure straight-line code, at the very least it seems like
> you could set it up so that the loop iterates only once per segment not
> page.
+1
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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