Re: Update Statistics
Andrew Ford said:
> For the following table on IDS versions 9.30xC2 and up
>
> create table t (
> a integer,
> b integer,
> c integer,
> d integer,
> e integer
> )>
> create unique index idx1 on t (a, b);
> create index idx2 on t (b, c, d);
> create index idx3 on t (b, c, e);>
> do
dostats.ec -- period!
> update statistics low for table t (a, b);
> update statistics low for table t (b, c, d);
> update statistics low for table t (b, c, e);>
> have the same net effect as
>
> update statistics low for table t (a, b, c, d, e);>
> ?
>
> and do
>
> update statistics medium for table t distributions only;
> update statistics high for table t (a) distributions only;
> update statistics high for table t (b) distributions only;
> update statistics high for table t (d) distributions only;
> update statistics high for table t (e) distributions only;>
> have the same net effect as
>
> update statistics medium for table t (c) distributions only;
> update statistics high for table t (a, b, d, e) distributions only;>
> ?
>
> Sorry if this has been answered before.
>
> Tried the following but no definitive answer was found.
>
> http://www3.software.ibm.com/ibmdl/pub/software/dw/dm/informix/0211desai/0211desai.pdf
> (understand the optimizer)
> http://www-128.ibm.com/developerworks/db2/zones/informix/library/techarticle/miller/0203miller.html
> (tuning update statistics)
> http://publibfp.boulder.ibm.com/epubs/pdf/8344.pdf (9.3 performance tuning
> guide)
> http://groups-beta.google.com/group/comp.databases.informix/browse_frm/thread/a852f14f35a0038d/6a2d537ae8d21b02?q=update+statistics+repeated+column&rnum=1&hl=en#6a2d537ae8d21b02
> (cdi post, but based on 7.21 recommendations)
>
> Also, anyone aware of SET EXPLAIN ON in 9.30.UC2 for update statistics
> only
> writing out 1 char to the sqexplain.out file?
>
> Thanks,
>
> Andrew
>
>
> sending to informix-list
>
--
Bye now,
Obnoxio
"C'est pas parce qu'on n'a rien ' dire qu'il faut fermer sa gueule"
- Coluche
A smile is a gift that is free to the giver and precious to the recipient.
But giving someone the finger is free too, and I find it more personal and
sincere.
sending to informix-list