Re: RE: sequential reads/scattered reads

From: oraora oraora <oraoraora_at_rediffmail.com>
Date: Thu, 11 Jul 2002 07:25:39 -0800
Message-ID: <F001.00494EAF.20020711072539@fatcity.com>

Cary Millsap,

i selected the top 25 SQL statements in the system over various periods . all are SELECT statements only waiting for reads.

querying v$session_wait also shows more than 10 records each for DB FILE SCATTERED READS and DB FILE SEQUENTIAL READS.does not it mean that it's b'coz of I/O contention ? i am not sure .

this is on RAID set up.
will not seperating my tables and indexes to seperate tablespace help me ?

guide me Cary.it's really urgent.
i am novice DBA.

On Thu, 11 Jul 2002 Cary Millsap wrote :
>Moving stuff around won't reduce I/O traffic, it'll just spread
>it
>around across different devices.
>
>Don't focus on how much I/O your system does, focus on how much
>*time*
>an important process spends *doing* I/O. It's Amdahl's Law: If
>you
>improve I/O latencies by 50%, but your program spends only 2% of
>its
>response time doing I/O, then your program's response time will
>improve
>by only 1%.
>
>
>Cary Millsap
>Hotsos Enterprises, Ltd.

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Received on Thu Jul 11 2002 - 10:25:39 CDT