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11.2.0.4

Heuristic TEMP Table Transformation

There are at least three different ways how the Oracle optimizer can come up with a so called TEMP table transformation, that is materializing an intermediate result set:- As part of a star transformation the repeated access to dimensions can be materialized- As part of evaluating GROUPING SETs intermediate result sets can be materialized- Common Subquery/Table Expressions (CTE, WITH clause)Probably the most common usage of the materialization is in conjunction with the WITH clause.This is nothing new but since I came across this issue several times recently, here's a short demonstration and a reminder that this so called "TEMP Table Transformation" - at least in the context of the WITH clause - isn't really cost-based, in contrast to most other optimizer transformations nowadays - although the unnest transformation of subqueries also has a "no-brainer" variant where costing isn't considered.The logic simp

Warning: Problems with 9.2 clients connecting to databases patched to 11.2.0.4…

I mentioned this a couple of days ago on Twitter, but I’ve only just go round to posting here…

I recently had to back out some 11.2.0.4 patches because the patch seems to cause problems with Oracle 9.2 client connections where 11.2.0.3 worked fine. I’m not sure how widespread the problem is. All I can tell you is we had two separate occasions (services) where this happened, so we’ve put a halt on patching to 11.2.0.4 until we can identify and upgrade the old clients.

Why are there 9.2 clients lurking around? In some cases it’s due to certification of legacy apps. In other cases it’s because the service owner has been working on a, “if it ain’t broke, don’t fix it”, basis. I guess now it’s broke, we gotta fix it. :)

If you have legacy client installations lurking around, you might want to tread carefully when testing this patch.

Good luck!