Re: Analyze

"Stephan" <test_at_test.com> wrote in message news:<wZko9.527393$2I.17016311_at_nlnews00.chello.com>...
> Oracle 7.3.4 and higher:
>
> - Is ANALYZING tables a MUST to achieve good performance?
> (imagine you NEVER analyze tables)

It depends. As Sybrand noted, if your application sql is written towards the rule-based optimizer, analysis may be bad. In a production environment where tables are imported from somewhere else, if YOU never analyze tables, someone else might have, and if any table in a query has been analysed, the CBO is immediately called into play, and users start screaming it's slow and programmers are protesting they haven't changed anything and what the heck is wrong, which is why you should never used optimizer_mode=choose if you are using any rule-based software.

As Daniel noted, it can be a very good thing, but I must temper that with the caution that CBO is just a sophomore (literally, sophisticated idiot) program, and will require some tweaking on some sql because it can do dumb things.

So as far as MUST goes, I'd say no. Most modern apps should be written with it in mind though. Also, new features may require it, and if those features are necessary for good performance, well, there you go. Most OTS software that has been around for a while hasn't been written for CBO. [other questions snipped, answered properly by others]

jg

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