RE: inefficient SQL detector

From: Christopher Spence <cspence_at_FuelSpot.com>
Date: Thu, 04 Oct 2001 13:41:46 -0700
Message-ID: <F001.003A2800.20011004134701@fatcity.com>

Have a look at the following script:

http://www.vampired.net/scripts/php/tuning.php (badsql.sql)

It allows you to run it against any database (8.1.6+) without having to adjust the buffer gets, executions, parsed calls to match the norm of the database.

On your script, it happens to return 0 rows on my test databases because of the execution count and the buffer gets being higher than my norm.

HTH, "Do not criticize someone until you walked a mile in their shoes, that way when you criticize them, you are a mile a way and have their shoes."

Christopher R. Spence
Oracle DBA
Phone: (978) 322-5744
Fax: (707) 885-2275

Fuelspot
73 Princeton Street
North, Chelmsford 01863

-----Original Message-----
Sent: Wednesday, October 03, 2001 5:26 PM To: Multiple recipients of list ORACLE-L

Yesterday while on a search for inefficient SQL I developed the following SQL;
which did a decent job of highlighting 1 - 2 dozen SQL statements that were HIGHLY inefficient. The goal was to identify the SQL that did a "lot" of buffer_gets (> 2000000); that ran "frequently" (> 100 times); that only returned a "few" number of rows (1-2 per execution) and that did "many" (> 1000) buffer_gets for each execution. You should adjust these criteria to better match your own application & environment.

select disk_reads, buffer_gets, rows_processed, executions, (buffer_gets/executions) ratio, sql_text from v$sql

where buffer_gets    > 2000000
 and  executions     > 100
 and  executions*2   > rows_processed

group by disk_reads, buffer_gets, rows_processed, executions, sql_text having (buffer_gets/executions) > 1000
order by 4
/

Alternatively this SQL can be order by 5

We are in the process of adding indexes that hopefully will GREATLY increase the selectivity of the SQL, rather than doing cartesian joins across tables.

HTH & YMMV!
--

Charlie Mengler                            Maintenance Warehouse  
charliem_at_mwh.com                           10641 Scripps Summit Ct.
858-831-2229                               San Diego, CA 92131    
United WE Stand!                           Justice WILL Be Served!

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Author: Charlie Mengler
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Author: Christopher Spence
INET: cspence_at_FuelSpot.com

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