Re: Performance Question - High I/O per Insert

  • From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Wed, 22 Sep 2004 20:46:15 +0100

Conventional path still uses array inserts.
How are you checking the costs - 
    logical I/Os divided by executes
    logical I/Os divided by rows_processed ?

If the former, then you are probably out by
a factor of the arraysize.    


Jonathan Lewis
The Co-operative Oracle Users' FAQ
Optimising Oracle Seminar - schedule updated Sept 19th

----- Original Message ----- 
From: "Mark Strickland" <mstrickland@xxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Wednesday, September 22, 2004 8:42 PM
Subject: Performance Question - High I/O per Insert

I'm trying to understand why I'm seeing a high number of I/Os for
inserts.  Inserts are through SQL*Loader conventional patch.  Average
row length is 129 bytes, no longs or blobs.  The table has five indexes
and each index has a blevel of 2.  According to v$sqlarea, each insert
uses 650 logical I/Os, 69 physical I/Os.  I would expect fewer than 20
I/Os per insert.  There are db file sequential read waits on the data
files that make up the index tablespace.  That file system also contains
the archived logs.  Not surprised at the contention.  Can someone point
me in the right direction to understand this?  Thx.

Mark Strickland

Seattle,  WA



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