Re: ** SQL QUERY TUNING

On Fri, 17 Apr 1998 17:09:20 +0200, Jürgen Kling <jkling_at_w-4.de> wrote:

>Who can help me to optimize the following SQL-Statement
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>select * from table
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>where tab_column = 1
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> or tab_column is null
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>Thje column TAB_COLUMN having an index, but ORACLE cant't use it. Thus
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>Oracle do an Full Table scan.
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>jkling_at_w-4.de

How many records are in the table? If there are very few, sometimes it is faster to perform a full table scan.

If the table has many records, then execute the following command on a SQL*Plus prompt:

ANALYZE TABLE table ESTIMATE STATISTICS;

Statistics about the table will be collected (number of rows, etc.) and accessible via the USER_TABLES view. The optimizer will take this into account when SQL statements are parsed, assuming you are using the COST-based optimizer.

Good luck,

Nuno Guerreiro Received on Fri Apr 17 1998 - 09:54:12 CDT