Re: O_DIRECT option used?

Read the developer's FAQ on advanced features.  We don't think it will
be a big win.

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Ruslan A Dautkhanov wrote:
>             Hello,
>
>         In the FreeBSD 4.5 appear additional O_DIRECT option for open(2),
>     which mean "eliminate or reduce cache effects". I think, that double
>     buffering the same disk blocks is ineffective. I grepped all
>     PostgreSQL sources for this options and didn't find this anywhere.
>     PgSQL have it's own disk caches, which should be smart
>     (DB can know what data should be cached first better than OS).
>     Why wasting OS memory for double caches? OS can use this caches
>     for other disk blocks, so total cached disk blocks in whole
>     system will be much bigger. If you have no plans to implement this,
>     please let us know what source files I should looking for patching.
>     I think it's somewhere DB tables files are opened (and maybe
>     WAL files too).   Thanks a lot on any comments.
>
>
>
>     ---
>      best regards,
>     Ruslan A Dautkhanov   rusland@scn.ru

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