Out of temp space

I would appreciate some help understanding how Oracle 8i uses Temp space for queries.

I have been working with a rather simple query, joining two tables and a couple of additional restrictions in the where clause.

Something like:

SELECT t1.field1, t1.field2, t2.field3
FROM table1 t1, table2 t2
WHERE t1.pk=t2.fk
AND criteria1 = 'some value'
AND criteria2 like 'other value %'

it worked nicely, ran in a few seconds.

Then I added an OR to it:

OR criteria2 like 'value %'

It ran for about 1/2 hour until it crashed with an ODBC error. It wasn't difficult to determine that the Temp datafile autoexended repeatedly until it finally ran out of disk space. Why would adding that OR criteria to the WHERE clause cause it to require so much additional TEMP?

-- 
Randy Harris
(tech at promail dot com)