RE: LOB Table - PCTVERSION 50%
Date: Fri, 21 Oct 2016 15:27:44 +0000
Message-ID: <CE70217733273F49A8A162EE074F64D90150344777_at_exmbx05.thus.corp>
Assuming your 22294's are being reported as the cause of the 1555's then you probably need more space for deleted LOBs; but the pctversion relates to percentage below current HWM of the LOB segment, but this does mean that if the LOB segment has only recently started filling and has not yet reached steady stats then 10% may be too small now, but will be sufficient in the future.
Broadly speaking there are usually no side effects to worry about with a larger pctversion - except the section of the LOBINDEX relating to "reusable space" can become that much larger.
Given that you're asking about pctversion I think you must be using basicfile LOBs. Have you considered using RETENTION rather than PCTVERSION - this allows the LOB segment to hold deleted LOBs until the time specified in the undo_retention parameter has passed.
There are lots of things about LOBs that are not documented - including nasty effects of concurrency and deletes/updates, and you might like to read the short series in my blog on LOB problems in case anything I say there matches your planned usage.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
_at_jloracle
From: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] on behalf of Nik Tek [niktek2005_at_gmail.com] Sent: 20 October 2016 20:19
To: ORACLE-L
Cc: Nik Tek
Subject: LOB Table - PCTVERSION 50%
Hi Oracle gurus,
I have a question, I'm noticing lot of ora-1555 and ora-22294 (snapshot too old) errors.
The default value is 10% for PCTVERSION as you all know.
I was wondering if I can change the value to 50%, would this have any side effects? How do I measure if there a problem?
I could not find much of the information related to PCTVERSION for LOB tables.
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Thank you
NikTeki
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Received on Fri Oct 21 2016 - 17:27:44 CEST