IDS Forum

Re: Auto Update Stats

Posted By: Nita Dembla
Date: Monday, 8 July 2013, at 6:03 p.m.

In Response To: Re: Auto Update Stats (BENJAMIN THOMPSON)

Hi Benjamin,

Your description of differentiation between STATCHANGE and AUS_CHANGE i=
s
right.

One important point to note is that in 12.10xC1, AUS now supports all t=
ypes
of databases - ANSI, logging and non-logging. Additionally AUS_CHANGE h=
as
been deprecated. The AUS evaluator now prioritizes the order of tables
based on the % of change.

AUS now relies on the server to automatically use STATCHANGE and determ=
ine
if the update statistics issued by AUS refresher should be run or be a
NO-OP. This allows users to apply specific change threshold at table,
database and server levels.

Regards,
Nita Dembla, PMP=AE
IBM Informix Development
Office: 404-238-4109 (T/L: 623-7266)
nita@us.ibm.com

=

"BENJAMIN =

THOMPSON" =

<benjamin.thompso =
To

n@bskyb.com> ids@iiug.org, =

Sent by: =
cc

ids-bounces@iiug. =

org Subj=
ect

Re: Auto Update Stats [30759] =

=

07/04/2013 07:21 =

AM =

=

=

Please respond to =

ids@iiug.org =

=

=

To follow-up on my own post, Anil has asked me by email what the
relationship
is between STATCHANGE in the onconfig file and the AUS_CHANGE parameter=
of
auto update stats. I don't think the Informix manuals make this very cl=
ear.

My understanding is - and I'd appreciate it if someone could confirm or=

correct it - the following:

STATCHANGE in the onconfig file takes effect when AUTO_STAT_MODE is set=
to
1.
It means that for ALL 'update statistics' commands run - whether by AUS=
, a
third-party tool or through dbaccess - that if the percentage of change=
d
rows
does not exceed STATCHANGE the 'update statistics' command will not do
anything and complete immediately. Confusingly it still returns the res=
ult
'statistics updated' though.

The value of STATCHANGE can be overridden on a per-table basis using AL=
TER
TABLE.

The value of AUS_CHANGE in sysadmin:ph_threshold just applies to AUS an=
d I
think it stops the evaluator flagging tables with insufficient change f=
or
any
statistics updates.

I think that if AUS_CHANGE is set lower than STATCHANGE in onconfig (wi=
th
AUTO_STAT_MODE on) the evaluator will flag some tables for refresh but =
when

they come to be run the 'update statistics' command will do nothing.

***********************************************************************=
********

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Messages In This Thread

• Auto Update Stats
  ANIL GOYAL -- Wednesday, 26 June 2013, at 10:26 a.m.
  • Re: Auto Update Stats
    Nita Dembla -- Wednesday, 26 June 2013, at 3:30 p.m.
    • Re: Auto Update Stats
      ANIL GOYAL -- Thursday, 27 June 2013, at 2:28 a.m.
      • Re: Auto Update Stats
        Nita Dembla -- Sunday, 30 June 2013, at 10:33 a.m.
        • Re: Auto Update Stats
          ANIL GOYAL -- Tuesday, 2 July 2013, at 1:24 a.m.
  • Re: Auto Update Stats
    BENJAMIN THOMPSON -- Wednesday, 3 July 2013, at 9:09 a.m.
    • Re: Auto Update Stats
      Art Kagel -- Wednesday, 3 July 2013, at 9:46 a.m.
    • Re: Auto Update Stats
      BENJAMIN THOMPSON -- Thursday, 4 July 2013, at 7:21 a.m.
      • Re: Auto Update Stats
        Nita Dembla -- Monday, 8 July 2013, at 6:03 p.m.

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