Re: increasing db_files_multiblock_read_count

From: Saar <sxmaxoz_at_us.oracle.com>
Date: Wed, 01 Jul 1998 12:15:08 -0700
Message-ID: <359A8ABB.A9FDD473@us.oracle.com>

oraclenews wrote:

> I have increased the parameter db_files_multiblock_read_count in the
> init<sid>.ora to 32.
>
> After a new instance startup the servermanager shows with the query
> show parameter db_files_ .... the value 15 ?
>

This pararameter has limits set for each port.1. It can't be bigger than 1/4 of the buffer cache.
2. Can't be bigger than max-io-transfer size divided by db_block_size.

As an example, on Digital Unix 8.0.X max-io-transfer is set to 1MB, so with block size of 8k
you'd get: 1048576/8192=128, so max for this parameter on this port is 128.

From your numbers, assuming db_block_size is 2K I guess max-io-transfer size would be
30720.

Remember it only comes into play for full table scans.

> Why ?
> Oracle 7.3.2.1.1. WSG NT40
> kind reguards
>
> Laszlo

--

 __  _    _  __    _ _   _   _ ___  ______________________________
((  /\\  /\\ ||)  |\V/| /\\ /\\ >/  Principal Performance Engineer

_))//-\\//-\\||\ |||||//-\\\\//<_ Oracle Corporation Digital SBU

////////////////// Drop x's in email (spam) //////////////////////

Received on Wed Jul 01 1998 - 14:15:08 CDT