These days, one also should be aware of the disk sector size. With 4K
disks, block size of 2K, which is technically possible, is not a good idea.
I generally raise a stern eyebrow when encountering tables with more
than 100 columns. More than 255 columns raises other important issues,
so row chaining is likely to be an unimportant problem.
But I agree with your sentiment with inline CLOBS and the new varchar2
size limits, it is easy to get to very long rows with fewer columns.
For those, it might be worth thinking about specific non-default
tablespaces.
That said, I highly doubt that the non-8K block will provide enough
benefit in enough situations across all aspects of an app to cause it to
be the default across an entire database. Which means mixing tablespace
block sizes. Which means administrative overhead. Which means job
security, and overtime calls. Which might be good for some DBAs, but
not me.
Therefore - benchmark. With realistic loads and volumes. And perform
ALL related DBA activities on the benchmark environment.
/Hans
Disclaimer: My opinions are my own, and do not necessarily reflect the
opinions of Oracle Corporation.
On 01/10/2015 1:03 PM, Lothar Flatz wrote:
In most tests a block size > 8k has no advatages.
There are some benefits of bigger block size however.
Depending on the data the compression ratio could be better. If you have very long rows (> 256 columns) a bigger block can allow to store those blocks more efficiently.
On 01.10.2015 17:12, Orlando L wrote:
"oracle really only tests on the 8k block size": interesting! They claim the product supports other blocksizes too!
There must be places where 8K blocks may not be big enough to store a row, even at 1% PCTFREE.
On Wed, Sep 30, 2015 at 4:53 PM, Andrew Kerber <andrew.kerber@xxxxxxxxx <mailto:andrew.kerber@xxxxxxxxx>> wrote:
I haven't seen any advantages from using any larger block sizes.
I also saw a Tom Kyte article a while back that said they are
only intended for use with transportable table spaces, and oracle
really only tests on the 8k block size.
Sent from my iPad
> On Sep 30, 2015, at 4:29 PM, Orlando L <oralrnr@xxxxxxxxx> wrote:
>
> List,
>
> Does anyone in the list use non default blocksize of greater
than 8K for your oracle DBs; if so, is it for warehousing/OLAP
type applications? What advantages do you get with them; any
disadvantage.
>
> Orlando.
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