Forum OpenACS Development: Re: OpenACS 4 Permissions scalability

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Posted by Jun Yamog on
Hi,

I wonder if Oracle CBO will have any impact on the queries?  Also PG vacumm analyze?

It looks good that we can improve on performance.

Anyway if needed to see how it scales, I can try it on my P4.  On a side note, going from P3 to P4 OACS does scale linearly.  So does CCM, CCM does get more juice if JDK 1.4 is used.  Although its a one off apache bench out of curiosity benchmark.

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Posted by Jeff Davis on
I vacuum analyze the test db regularly so that's not an issue with the numbers I posted. The default on oracle is to use the CBO. I have seen some queries like this where the rule based optimizer is faster (sometimes a lot faster) but it's hit and miss (and I think dependent on quirks of both the data and the rule based optimizer). One other hint which sometimes made a difference for oracle was to say /*+ FIRST_ROWS */ (I think thats right, though it's from memory).

I don't know what people think about trying to tweak the queries like that since it's all such a black art (to me at least).