EXPERT RESPONSE
The ANALYZE command provides Oracle with the ability to collect statistics that are then used by the optimizer. The optimizer MUST have up to date statistics to allow your SQL to perform at its best. You must make sure that your statistics on a table and index are up to date, so you should analyze your tables on a regular basis.
However, before we go much further, you should note that you should use the Oracle supplied package, DBMS_STATS. You should not use the ANALYZE command as it does not deal well with many of the features that tables can utilize today. So please remember to always use DBMS_STATS to analyze your table.
There are lots of books that go into great depth on the subject of using DBMS_STATS and reading explain plans that will provide you with the background for better utilizing this important feature of the Cost Based Optimizer.
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