On 27.04.2007 07:31, Mladen Gogala wrote:
> 3) When you have very write-intensive application and relatively slow
> peripherals. I frequently see compressed tables used on Linux boxes
> which have notoriously low I/O capacity. I work for a company that
> is loading tons of data (~ 3,000,000 records a day) into several
> tables for later processing. I tuned I/O well (6 4GB redo logs,
> 8MB log buffer, 2 DB writer processes, asynchronous I/O, 20 freelists,
> 25% of free space, 32 inittrans, reverse index for primary key and
> the analog boxes feeding the database were still too fast. I also
> went after the Linux kernel and fixed network parameters, Ext3
> mount options and the Ethernet drivers. My compressing few critical
> tables made a difference and caused the boxes to report backlog once
> a week instead of once a day. It has cut down the number of I/O
> requests for approximately 12% which was enough. Once we overgrow
> that, the only thing to do will be to buy a box with more I/O
> bandwidth.
I guess with "write intesive" you mean "will be frequently truncated and
bulk loaded / recreated". Tom Kyte writes in "Effective Oracle by
Design" that modified blocks are not compressed. So in an OLTP
application you likey won't benefit from table compression.
Kind regards
robert
Received on Fri Apr 27 2007 - 04:39:32 CDT
