RE: Anyone using multi-block sizes for their databases
- From: "Murching, Bob" <bob_murching@xxxxxxxxx>
- To: "'lex.de.haan@xxxxxxxxxxxxxx'" <lex.de.haan@xxxxxxxxxxxxxx>, "'juancarlosreyesp@xxxxxxxxx'" <juancarlosreyesp@xxxxxxxxx>, "'Oracle-L@xxxxxxxxxxxxx'" <Oracle-L@xxxxxxxxxxxxx>
- Date: Thu, 21 Jul 2005 14:33:31 -0400
I more or less agree with the below sentiment. We moved to multiple block
sizes pretty aggressively out of the gate with 10g, then quickly ended up
cutting our losses and going back to an database-wide standard. It was
mostly a manageability issue - with multiple block sizes, now we had one
more thing to worry about: tuning the different buffer cache pools. Once
you take a few moments to look at the capability and its primary weakness,
you quickly realize that it's only a matter of time before Oracle
auto-allocates RAM to the different buffer cache pools. I think we'll be
taking advantage of multiple block sizes if and when that functionality
becomes available. Until then, "just pick 8k or 16k, then go back to tuning
the SQL and building the right data model" remains the most effective
mechanism for tuning....
-----Original Message-----
From: Lex de Haan [mailto:lex.de.haan@xxxxxxxxxxxxxx]
Sent: Thursday, July 21, 2005 12:52 PM
To: juancarlosreyesp@xxxxxxxxx; Oracle-L@xxxxxxxxxxxxx
Subject: RE: Anyone using multi-block sizes for their databases
Juan,
with all due respect, I believe this is *not* a good advice. I actually
think it is a *bad* advice. you try to achieve something with the wrong
technique, at a way too high price.
let me first say that the only *intended* reason for multiple blocksizes is
to make transportable tablespaces more flexible. any other reason might have
its merits, but should be considered with caution.
the biggest disadvantage of a segmented cache is that free space gets
segmented too, obviously -- typically leading to much more memory wastage
than with a single unsegmented buffer cache.
kind regards,
Lex.
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Juan Carlos Reyes Pacheco
Sent: Thursday, July 21, 2005 18:45
To: Oracle-L@xxxxxxxxxxxxx
Subject: Re: Anyone using multi-block sizes for their databases
Hi,
This works really nice, this allows to create separate areas of memory for
different things.
For example big blobs documents, in a 32k normal tables 8k indexes 16k, etc.
etc.
You have to set the database memory cache in the init.ora for each different
block size.
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