Re: Compression Level

yuvalyuval wrote:
>
> Hi,
>
> I would like to compress some Oracle tables to see how well they can
> compress. Is there some sort of a guide or rules for how well tables
> can compress based on their datatypes? I know that some of our DBA's
> have managed to compress tables up to 70%.
>
> What tables if any shouldn't be compressed? Are there datatypes that
> compresses better or is it block related only?
>
> I would like to understand and decide which tables should be compressed
> without testing each table.
>
> Thanks,
>
> Yuval

compress is very much for direct mode operations. If you're doing dml on a table, then compress is most likely going to cause pain.

other than that, compression is all about efficiencies with repeating values within a block , so if you haven't got repeating values (or those repeated values are splattered all over table, then you may not get great rewards.

hth
connor

-- 
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
Co-author: "Oracle Insight - Tales of the OakTable"

web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald_at_yahoo.com


"GIVE a man a fish and he will eat for a day. But TEACH him how to fish,
and...he will sit in a boat and drink beer all day"

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