Re: Index Compression question

Jan

If you're using CBO, the stats for the indexes might need to be rebuilt. That could explain why user stuff is slow (Oracle avoiding indexes without stats) and a heavy duty task (batch perhaps?) is running faster (it's also avoiding an index - this time one that wasn't a help - often the case if you're reading a large %age of the table thru the index).

Andy

"Jan Gelbrich" <j_gelbrich_at_westfalen-blatt.de> wrote in message news:b08kg8$n044m$1_at_ID-152732.news.dfncis.de...
> Hello,
>
> due to most information I have (the doc, some books and NG FAQ),
> index compression can be good for performance,
> on compressable indexes only, of course.
>
> Last night I compressed half of my indexes (most composites, their
> cardinalities were good enough to do so),
> which reduced space requirements as I expected,
> but today, when all people are at their
> working places again, everybody complains that I made the whole system
slow
> down -
> expect of one heavy duty task, which runs as fast as never before.
>
> I know that there are various reasons why a system can be slow eventually,
> but for now I want to make sure that it was not due to my actions ...
>
> So my Question is: does index compression have *negative* performance
> effects ?
> If so, I would have to rebuild some crucial indexes again with NOCOMPRESS
> ...
>
> I would appreciate any comments from the experienced gurus ...
>
> Jan
>
>
Received on Fri Jan 17 2003 - 04:39:12 CST