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RE: Use of Multiple BLOCK Sizes ?

From: Mark W. Farnham <>
Date: Tue, 19 Dec 2006 11:27:16 -0500
Message-ID: <>

IMHO, perfectly and succinctly stated, Chris.

At this writing it should also be noted that I have never seen a definitive publication of whether Oracle ever plans to fully support transportable tablespaces (and as a side effect more completely support long term use of multiple database block sizes within a single instance) by incorporating multiple block size cache allocation (by demand? by target? by target dynamically modified by workload demand?) into automated memory allocation. Current releases require individual buffer cache specifications for each block size you have if you have multiple block sizes, which adds the tradeoff of "wasting" some memory some of the time unless your actual workload demand for buffers is constant by block size. (That is unlikely to be true unless you are specifically building such a case in a laboratory experiment.) I'm not even sure whether anyone at Oracle considers it a worthy task, let alone thinks it should rise to implementation priority. Since Oracle has repeatedly stated that the intent of multiple block sizes in the database is for full support of transportable tablespaces, as opposed to being for performance issues, the impetus for multiblock size automated cache size support is most productively supported on manageability grounds. (So if all y'all want to eliminate one downside to multiple block sizes in a single database for performance, the problem that needs to be highlighted is that you have many tablespaces far to large to unload and reload that differ in block size and therefore will interfere with utiliation of Oracle's automation features if you move to an integrated global database. Mentioning performance and multiple block sizes in the same conversation seems to universally result in pulling the neck cord on the talking doll with the pre-selected recording: "Multiple block sizes are not intended for performance.")


-----Original Message-----
From: []On Behalf Of Christian Antognini
Sent: Tuesday, December 19, 2006 9:37 AM To:
Subject: RE: Use of Multiple BLOCK Sizes ?


> Does use of Multiple BLOCK sizes (for different Tablespaces) help in
> Performance of a Hybrid Application?

Every decision you take about the physical storage of a table has an impact on performance. Every. However, how significant the impact is and if it is good or bad depends on the utilization of the blocks. Therefore, IMHO, to find the best storage options you have to carefully understand your data and how Oracle and your application use it.



Received on Tue Dec 19 2006 - 10:27:16 CST

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