Re: ANALYZE and its impact on queries

Compute will generate more accurate statistics. However 20 percent will give you a pretty good sample and is an acceptable alternative if 1. you don't have the temp space for the compute, or 2. you don't have the time. And I think if you estimate using 40+ percent (or is it 30 percent?), you are getting a compute in the background anyway.

Lisa
Minneapolis,MN,USA

Dan.Hubler_at_midata.com on 06/21/2000 02:10:18 PM

Please respond to ORACLE-L_at_fatcity.com

To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> cc: (bcc: Lisa Koivu/GELCO)

Subject: ANALYZE and its impact on queries

Have a data warehouse.

Did an ANALYZE on all the tables using the ESTIMATE STATISTICS SAMPLE 10 PERCENT clause.

A query that runs for a long time given that scenario.

Did another ANALYZE on the tables using COMPUTE STATISTICS.

Explain plan show that join operation(s) change from nested loop to hash.

Does ANALYZE with COMPUTE populate any more statistics than ANALYZE with ESTIMATE does?
Or just provide more accuracy?

Thanks.

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