| From: | Matthew Kirkwood <matthew(at)hairy(dot)beasts(dot)org> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | pgsql-patches(at)postgresql(dot)org |
| Subject: | Re: A patch for xlog.c |
| Date: | 2001-02-24 23:01:06 |
| Message-ID: | Pine.LNX.4.10.10102242240090.17152-100000@sphinx.mythic-beasts.com |
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| Thread: | |
| Lists: | pgsql-hackers pgsql-patches |
On Sat, 24 Feb 2001, Bruce Momjian wrote:
> I am confused why mmap() is better than writing to a real file.
It isn't, except that it allows to initialise the logfile in
one syscall, without first allocating and zeroing (and hence
dirtying) 16Mb of memory.
> Don't we need to write to a real file so it is available for database
> recovery?
The mmap isn't used for the destination, but for the source;
it's just a cheap way to get your hands on 16Mb of zeroes.
Matthew.
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