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Fri, 26 September 2014 15:41

oasisin2014
Messages: 8
Registered: September 2014

Junior Member

Any suggestions to speed up a query with union all?

The query is:
Table1 union all Table2 union all Table 3 .

Fri, 26 September 2014 15:43

oasisin2014
Messages: 8
Registered: September 2014

Junior Member

Please give some suggestions. Thanks

Fri, 26 September 2014 15:43

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

Welcome to this forum.

Please read and follow the forum guidelines, to enable us to help you:

http://www.orafaq.com/forum/t/88153/0/ and read http://www.orafaq.com/forum/t/174502/

Since NOBODY can optimize SQL just by looking at it, we need a few more details.
http://www.orafaq.com/forum/m/433888/136107/#msg_433888
Please refer to URL above & be sure to provide the details requested:
1) DDL for all tables & indexes
2) EXPLAIN PLAN
3) output from SQL_TRACE & tkprof

Sat, 27 September 2014 01:02

Michel Cadot
Messages: 68765
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

Quote:

Any suggestions to speed up a query with union all?

Truncate the tables.

Sat, 27 September 2014 11:22

Lalit Kumar B
Messages: 3174
Registered: May 2013
Location: World Wide on the Web

Senior Member

Or, add Where clause to filter the data for individual tables Smile

And create respective indexes as and when required.

Since, in a production enviroment, nobody wants entire data from the tables.

[Updated on: Sat, 27 September 2014 11:24]

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