RE: Caching a huge table's data in memory

Read Cary Millsap's papers on Misunderstandings about Oracle Internals at his site www.hotsos.com <http://www.hotsos.com> . They are excellent!

-----Original Message-----
Sent: Tuesday, January 07, 2003 9:54 AM
To: Multiple recipients of list ORACLE-L

I don't think a cache table is actually "pinned" in memory. It just means that its blocks stick around once they are read and are not recycled as much as "normal" tables. That having been said, due diligence should be taken to tune the queries and caching large tables should be avoided. What good is it if you "tune", or rather, speed up one query if it takes resources
away from other queries and slows down the overall system? Sounds like a good opportunity to educate a DUHveloper. Tune the query and show her/him before and after tkprof stats. Better yet, teach her/him how to use tkprof and make them run it on each query before putting it into code. Make sure your test/development data set reflects production volumes.

Steve Orr
Bozeman, Montana

-----Original Message-----
Sent: Tuesday, January 07, 2003 8:09 AM To: Multiple recipients of list ORACLE-L

Pro: It is in memory

Con: You must buy the memory. You must be sure you don't cause the box to start paging to swap ... very bad ... VERY bad.

When you live in the land of bad applications, sometimes the politics of the

situation are such that you just do what you know is the equivalent of "fixing" things with duct tape -- a whole lot of duct tape -- rather than attempt to engage in a hopeless fight. Consider the case of an application that is so bad that a box with more than 50 Gb of RAM and 16 Alpha CPU's are

required to handle from 6 to 10 active connections. Hey, if they want to spend the money ....

> -----Original Message-----
> What are the pros and cons of caching a table's data?

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