Sunday, November 27, 2011

Who is using your Undo space? - Improved Script

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Hi folks!
I have extended the Undo usage scripts to include two additional indicators:
1) undo change vector size statistics
2) Used undo records/blocks

and support for RAC infrastructure, so you can spot the hungriest UNDO eaters for any given instance.

Then the script for Oracle 11g is as follows:
set pagesize 400
set linesize 140
col name for a25
col program for a50
col username for a12
col osuser for a12
SELECT a.inst_id, a.sid, c.username, c.osuser, c.program, b.name,
a.value, d.used_urec, d.used_ublk
FROM gv$sesstat a, v$statname b, gv$session c, gv$transaction d
WHERE a.statistic# = b.statistic#
AND a.inst_id = c.inst_id
AND a.sid = c.sid
AND c.inst_id = d.inst_id
AND c.saddr = d.ses_addr
AND a.statistic# = 284
AND a.value > 0
ORDER BY a.value DESC

If you want to run this script on versions 10g1 and 10g2, just replace the statistic# with 176; 216 if your database is 11gR1... or use the following version independent script!!! (Hope we don't change the statistic name).

set pagesize 400
set linesize 140
col name for a25
col program for a50
col username for a12
col osuser for a12
SELECT a.inst_id, a.sid, c.username, c.osuser, c.program, b.name,
a.value, d.used_urec, d.used_ublk
FROM gv$sesstat a, v$statname b, gv$session c, gv$transaction d
WHERE a.statistic# = b.statistic#
AND a.inst_id = c.inst_id
AND a.sid = c.sid
AND c.inst_id = d.inst_id
AND c.saddr = d.ses_addr
AND b.name = 'undo change vector size'
AND a.value > 0
ORDER BY a.value DESC
 
Read the popular 2008 article Who is using your UNDO space?

Interested on MySQL Performance? Read  Book Review - High Performance MySQL


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Wednesday, November 23, 2011

First pervasive-post

Today I'm writing this post from a Samsung Galaxy, my hand sized tablet, camera included, microphone and lots of fun.

I have been busy this year and that is thanks to the tremendous success of the Database Machine/Exadata.

Traveled all over the caribbean and south america, plus my first OOW experience as Oracle employee: always exciting!



Bandeja Paisa / Paisa "tray" - Medellin, Colombia


Sao Paulo Subway System

Oracle Open World 2011
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