Cost Based Analysis

From: Ken Whitaker <kwhitake_at_moon.jic.com>
Date: 1997/02/26
Message-ID: <01bc2440$f2d0ac40$43cf87d0@kwhitake.jic.om>#1/1

What is the difference between

analyze table XXXX ESTIMATE statistics; analyze table XXXX COMPUTE statistics;

One of my developers ask me the question; I know the usual compute looks at every row in the table vs estimate does a percent of the table. The estimate is quick vs compute may take a while for a large table.

The table is locked while the analyze is running ie can't drop it.

I usually am faced with explaining the rule vs cost to developers but this question has
merit. Looking at the explain plan I noticed no difference on queries; whereas without
any analyze ie rule based may use a different explain plan.

Anyone noticed anything, I tend to tell folks to use the estimate as it runs faster; why would the
compute be better to use.

Platform Solaris 2.5.1 / Oracle 7.3.2.3 / 50,000 rows - 2mil row tables

Thanks,
kwhitake_at_moon.jic.com Received on Wed Feb 26 1997 - 00:00:00 CST