Re: Multiple Indexing, performance impact

> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Strange that even at 1024 performance still drops off at 7. Seems it
> > may be more than buffer thrashing.
>
> Yeah, if anything the knee in the curve seems to be worse at 1024
> buffers. Curious. Deserves more investigation, perhaps.
>
> This does remind me that I'd been thinking of suggesting that we
> raise the default -B to something more reasonable, maybe 1000 or so
> (yielding an 8-meg-plus shared memory area). This wouldn't prevent
> people from setting it small if they have a small SHMMAX, but it's
> probably time to stop letting that case drive our default setting.
> Since 64 is already too much to let 7.1 fit in SHMMAX = 1MB, I think
> the original rationale for using 64 is looking pretty broken anyway.
> Comments?

BSD/OS has a 4MB max but we document how to increase it by recompiling
the kernel. Maybe if we fail the startup we can tell them how to
decrease the buffers in postgresql.conf file. Seems quite clear.

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