Home » RDBMS Server » Performance Tuning » How gathering of stats/ analyze stats work? (10g)
How gathering of stats/ analyze stats work? [message #338973] Wed, 06 August 2008 06:23 Go to next message
beetel
Messages: 96
Registered: April 2007
Member
My colleague says that during gathering of statistics, what happens is that data scattered throughout different blocks are defragmented and put in a sort of adjacent/continuous blocks. I thought that there is no such movement in location of data - but what happens is that the stats table is updated on 'where' the data are and so Oracle can know where to locate them quickly by reading that table.. Am confused here.. please enlighten.
Re: How gathering of stats/ analyze stats work? [message #338984 is a reply to message #338973] Wed, 06 August 2008 06:55 Go to previous messageGo to next message
Michel Cadot
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Registered: March 2007
Location: Nanterre, France, http://...
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Your colleagues are wrong.
Gathering statistics is just gathering statistics.

Regards
Michel
Re: How gathering of stats/ analyze stats work? [message #338994 is a reply to message #338984] Wed, 06 August 2008 07:11 Go to previous messageGo to next message
beetel
Messages: 96
Registered: April 2007
Member
thanks... that colleague is my boss. So am now searching for some real, hard evidence (documentation) to show him.
If you can also provide me with the same (link) that will be really great.
Re: How gathering of stats/ analyze stats work? [message #339009 is a reply to message #338994] Wed, 06 August 2008 08:40 Go to previous messageGo to next message
Michel Cadot
Messages: 64132
Registered: March 2007
Location: Nanterre, France, http://...
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There is no documentation saying what something does not do. I'm pretty sure gathering does not make coffee nor mow the lawn and I'm pretty sure this is mention nowhere.
Ask him to provide you a document that says gathering does what he said.

Regards
Michel
Re: How gathering of stats/ analyze stats work? [message #339012 is a reply to message #338973] Wed, 06 August 2008 08:48 Go to previous message
BlackSwan
Messages: 25045
Registered: January 2009
Location: SoCal
Senior Member
1) pick a table (TABLE_A) & then save ROWIDS to a NEWTABLE1.
2) Gather STATS
3) Save ROWIDs of TABLE_A to NEWTABLE2
4) select * from NEWTABLE1 minus select * from NEWTABLE2.
If "boss" is correct, then many rows returned.
If reality is correct, few or zero rows returned.
(new rows may be reported/returned) & can be eliminated by using date/timestamp qualifier.
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