Re: db_file_multiblock_read_count causing full scans to take longer?

Ah sorry I forgot to mention those. I'm on 10.2.0.2 (32-bit Linux). The system MBRC is currently 5, although that is very old and I've been gathering system stats to a user stats table for the past week that indicate that have it at 13 or 14.

I'll try to get that other info shortly.

Don.

On 12/19/06, Allen, Brandon <Brandon.Allen_at_oneneck.com> wrote:
> What version? What is your mbrc system stat?
>
> Yes, the higher dbfmbrc should generally improve the speed of full
> scans, that is assuming that it actually makes a difference in the
> number of required I/O operations. Often the effective multiblock read
> size isn't even close to your dbfmbrc setting due to some blocks already
> being cached, extent boundaries, etc. Are you sure you have the exact
> same plan for this query before and after the increase in dbfmbrc? Can
> you share the plans, executions statistics and wait event summary (9i+)
> from tkprof with both dbfmbrc settings? Be sure to run the trace with
> WAITS and statistics_level=all.
>
> Regards,
> Brandon
>
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