| sample size in user_table [message #273816] |
Thu, 11 October 2007 15:05  |
navkrish
Messages: 189
Registered: May 2006
Location: NJ,USA
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Senior Member |
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running below query
SELECT table_name, MONITORING, num_rows, sample_size,
TO_CHAR (last_analyzed, 'DD/MM/YYYY HH24-mi-ss') analyzed
FROM all_tables
WHERE table_name = 'BUSINESS_NAME_BNM'
output in db 1:
BUSINESS_NAME_BNM NO 27535125 5081100 08/10/2007 08-44-37
output in db 2:
BUSINESS_NAME_BNM NO 28533200 0 11/10/2007 00-10-53
1) any reason why it could be?
2) what is the significant of sample_size?
Regards,
Naveen
[Updated on: Thu, 11 October 2007 15:06] Report message to a moderator |
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| Re: sample size in user_table [message #273818 is a reply to message #273816] |
Thu, 11 October 2007 15:27  |
OracleDisected
Messages: 25
Registered: September 2007
Location: Mexico
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Junior Member |
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When you have gathered statistcs with estimation instead of calculation. Estimation takes a percentage of blocks (sample size) in order to estimate rows for table.
Regards
[Edit MC: url to poster blog removed. We don't care about your blog in this post. If you have an answer on your site, post a link to this answer. If you don't, post your blog url in Marketplace]
[Updated on: Fri, 12 October 2007 00:01] by Moderator Report message to a moderator |
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| Re: sample size in user_table [message #273830 is a reply to message #273816] |
Thu, 11 October 2007 17:44 |
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BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal
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Senior Member |
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which is better? good, fast or cheap???
compute is more accurate than estimate; but compute consumes more resources than estimate.
How close is "good enough"?
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