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Message Posted: Fri, 19 Sep 2003 @ 21:17:27 GMT
It seems unlikely that the case statements in and of themselves are the problem. More likely there are execution plan differences between the select count(*) and the actual query. This is likely because of the difference in size of the spool files as a result of the number of projected columns in the actual query vs. the select count(*). This can for example influence join ordering or join geography.
As to why the actual query suddenly started running longer my first advise would-be to review the actual queries explain and look for issues. Example issue are duplicating large tables or redistributing a large table on a non unique value.
If you have a old explain to compare with that would be better yet.
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