Re: Index Compression question - afterquestion

Howard / Niall / Jan

Yep - just checked 8.1.7 as well - it doesn't appear to wipe stats on a rebuild. There goes another assumption lurking as a false training memory :-). Just goes to show. That now leaves Jan's question about poor performance after the rebuild unanswered. If it was okay before and we know the stats haven't changed what caused a slow down ?

Andy

"Andy" <andy.spaven_at_eps-hq.co.uk> wrote in message news:4uOW9.3530$9R.12191378_at_newsr2.u-net.net...
> Jan
>
> Not OS swapping - the move from non compressed to compressed indexes - if
> you'd done ALTER INDEX ... REBUILD COMPRESS COMPUTE STATISTICS NOLOGGING
> things might have been okay. Without the COMPUTE STATISTICS keywords I
> think you loose the statistics already gathered (much like dropping and
> recreating an index). Someone correct me if I'm wrong on this point.
>
> Andy
>
> "Jan Gelbrich" <j_gelbrich_at_westfalen-blatt.de> wrote in message
> news:b0bkqt$o4r2s$1_at_ID-152732.news.dfncis.de...
> > Hi, Andy ...
> >
> > "Andy" <andy.spaven_at_eps-hq.co.uk> schrieb im Newsbeitrag
> > news:mlVV9.3528$9R.12113872_at_newsr2.u-net.net...
> > > Jan
> > >
> > > I suspect that your stats were up to date but that the process of
> swapping
> > > to compressed destroyed them.
> >
> > please excuse me, I am not sysad,
> > could You be so kind to explain
> > how OS swapping can destroy statistics in the data dactionary ?
> >
> > > Did you drop and recreate the indexes or
> > > rebuild them ? If you rebuilt them did you specify compute statistics
> > > clause otherwise you loose stats (I believe) ?
> > >
> > > Andy
> > >
> >
> > This is what I did:
> >
> > ALTER INDEX ...
> > REBUILD
> > (no)compress --depends on the index
> > nologging
> > /
> >
> > And I always use COMPUTE to fresh up statistics
> > using ANALYZE or DBMS_UTILITY.
> >
> > P.S. As Daniel mentioned, I should use DBMS_STATS instead ...
> >
> > Jan
> >
> >
> >
>
>
Received on Tue Jan 21 2003 - 05:03:40 CST