RE: What does LIKE '%%' actually do in a WHERE clause?

>> and if we are going to use rownum then it will be always
>> faster I suppose..

Both queries used the rownum < 101 to just get the first 100 rows.

The one with % in the WHERE clause (and the one with nothing except the joins between tables) takes over 7 minutes - it has huge cardinalities and I'm sure that it's joining all 4 tables and then returning the first 100 rows.

The one with %% joins the tables and bungs back the same 100 rows in a couple of seconds.

<SNIP>

>> not very sure randomly guess may be '%%' will ignore nulls..
Yes, % won't match nulls.

Thanks.

Cheers,
Norm.

Norman Dunbar
Contract Senior Oracle DBA
Capgemini Database Build Team
Internal : 7 28 2051
External : 0113 231 2051

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