Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
>> For that matter, I would expect that O_DIRECT also defeats readahead,
>> so I'd fully expect it to be a loser for seqscans too.
> I am told on FreeBSD it does not disable read-ahead, just caching;
> something that needs more research.
Hmm. I always thought of read-ahead as preloading buffer cache entries.
It'd be interesting to get a description of *exactly* what this flag
does, rather than handwavy approximations. Time to start reading the
kernel code, I suppose.
regards, tom lane
In response to
pgsql-hackers by date
|Next:||From: Brent Verner||Date: 2002-01-04 21:59:50|
|Subject: Re: More problem with scripts|
|Previous:||From: Brent Verner||Date: 2002-01-04 21:53:34|
|Subject: Re: O_DIRECT use|