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IDS Forum
Re: Update statistics issue
Posted By: Art Kagel
Date: Friday, 27 June 2014, at 1:18 p.m.
In Response To: Re: Update statistics issue (medkba)
Ooo, now you're getting into a bone of contention between very good
friends. John wrote the AUS functions and has good reason to think they
are doing the best job possible. I wrote dostats and have good reason to
think that it does the best job possible. Honestly in most cases both will
work excellently. There are some specific databases on which one or the
other will either be faster or will produce slightly better quality data
distributions. One nice feature of AUS is that it will duplicate your
existing levels of distributions if you turn on that flag in the
ph_threshold table so you can preset the levels of distributions you want
using dostats and then let AUS maintain them over time. You can do the
same with my tools by using the myschema --distributions=filename option to
generate an SQL script you can run to reproduce/refresh the current level
of distributions.
Art
Art S. Kagel, Principal Consultant
ASK Database Management
Blog: http://informix-myview.blogspot.com/
Disclaimer: Please keep in mind that my own opinions are my own opinions
and do not reflect on the IIUG, nor any other organization with which I am
associated either explicitly, implicitly, or by inference. Neither do
those opinions reflect those of other individuals affiliated with any
entity with which I am affiliated nor those of the entities themselves.
On Fri, Jun 27, 2014 at 12:46 PM, medkba <medkba@gmail.com> wrote:
> Art and John,
>
> Which is best way either to do manual or automatic. My Informix engine
> version is 11.50 FC9.
>
> Currently, this job is running manual using shell script on the HP-UX
> PA-RISC and recently we have migrated to HP integrity server so that
> expectation of this job running faster but it is slower compare to HP-UX
>
> Thank you very much
>
> On Sat, Jun 28, 2014 at 12:40 AM, John Miller iii <miller3@us.ibm.com>
> wrote:
>
> > Art:
> >
> > The newer (all the C versions) of aus_refesh wait for update to 5 minutes
> > for the aus_evaluator to
> > complete before starting any real processing. The accomplish this by
> > checking for the
> > existence of the aus_command table. If this table exists then the
> > aus_refresh will
> > sleep for 15 seconds and check again. It will loop for 20 times before
> > proceeding
> > I see now that a maximum of 5 minutes of wait time is to short and will
> > increase
> > this wait time.
> >
> > John F. Miller III
> > STSM, Lead Architect
> > miller3@us.ibm.com
> > 503-747-1366
> > IBM Informix Dynamic Server (IDS)
> >
> > ids-bounces@iiug.org wrote on 06/27/2014 09:20:31 AM:
> >
> > > From: "Art Kagel" <art.kagel@gmail.com>
> > > To: ids@iiug.org,
> > > Date: 06/27/2014 09:22 AM
> > > Subject: Re: Update statistics issue [33302]
> > > Sent by: ids-bounces@iiug.org
> > >
> > > Yes, either disable them or change them to run further apart and rely
> on
> > > what they do and disable your own scripts. Right now it looks like the
> > > refresh is running 11 minutes after the evaluator starts running and
> that
> >
> > > can't be right unless your database has very few tables. If you decide
> to
> >
> > > keep AUS running and abandon your own scripts then you should look in
> the
> >
> > > ph_run table to see how long the evaluator actually runs for (columns
> > > duration) and change the scheduling for the AUS refresh task:
> > >
> > > select * from ph_run where run_task_id = 18;
> > >
> > > Art
> > >
> > > Art S. Kagel, Principal Consultant
> > > ASK Database Management
> > >
> > > Blog: http://informix-myview.blogspot.com/
> > >
> > > Disclaimer: Please keep in mind that my own opinions are my own
> opinions
> > > and do not reflect on the IIUG, nor any other organization with which I
> > am
> > > associated either explicitly, implicitly, or by inference. Neither do
> > > those opinions reflect those of other individuals affiliated with any
> > > entity with which I am affiliated nor those of the entities themselves.
> > >
> > > On Fri, Jun 27, 2014 at 11:51 AM, medkba <medkba@gmail.com> wrote:
> > >
> > > > Thank you very much Art
> > > >
> > > > The below output executing the query
> > > >
> > > > tk_id 18
> > > > tk_name Auto Update Statistics Evaluation
> > > > tk_enable t
> > > > tk_next_execution 2014-06-28 01:00:00
> > > >
> > > > tk_id 19
> > > > tk_name Auto Update Statistics Refresh
> > > > tk_enable t
> > > > tk_next_execution 2014-06-28 01:11:00
> > > >
> > > > It means that statistics running automatically. Am i right? I need to
> > > > disable both
> > > >
> > > > On Fri, Jun 27, 2014 at 11:39 PM, Art Kagel <art.kagel@gmail.com>
> > wrote:
> > > >
> > > > > There are two AUS tasks, the AUS evaluator that determines what
> > tables
> > > > need
> > > > > their stats updated and the AUS refresh task that executes the
> > commands
> > > > > calculated by the evaluator. You can find the task manager records
> > > > > governing their execution in the sysadmin database in the table
> > ph_task.
> > > > > Run:
> > > > >
> > > > > select tk_id, tk_name, tk_enable, tk_next_execution
> > > > > from sysadmin:ph_task
> > > > > where tk_execute matches 'aus*';
> > > > >
> > > > > If tk_enable is set to 't' then the AUS tasks are running.
> Obviously
> > if
> > > > > the evaluator is executing but the refresh is not, then stats are
> not
> >
> > > > being
> > > > > updated by AUS and if the refresh is running without the evaluator
> > > > running
> > > > > before it then the list of work its doing is probably out-of-date
> and
> > may
> > > > > even be empty. The tk_next_execution column will tell you when each
> > is
> > > > > scheduled to run next. Note that in 11.50 the evaluator was rather
> > > > > inefficient and could take longer to run than the default
> difference
> > in
> > > > the
> > > > > scheduled run times of the two tasks (1 hour) so that when the
> > refresh
> > > > > launched the evaluator may not have finished running resulting in
> the
> >
> > > > > refresh only processing some of the tables that needed to updated.
> > This
> > > > > was fixed in 11.70 and again in 12.10 by recoding the evaluator to
> > run
> > > > > faster and by changing the default scheduling of the tasks so they
> > run
> > > > > further apart.
> > > > >
> > > > > Art
> > > > >
> > > > > Art S. Kagel, Principal Consultant
> > > > > ASK Database Management
> > > > >
> > > > > Blog: http://informix-myview.blogspot.com/
> > > > >
> > > > > Disclaimer: Please keep in mind that my own opinions are my own
> > opinions
> > > > > and do not reflect on the IIUG, nor any other organization with
> which
> > I
> > > > am
> > > > > associated either explicitly, implicitly, or by inference. Neither
> do
> >
> > > > > those opinions reflect those of other individuals affiliated with
> any
> >
> > > > > entity with which I am affiliated nor those of the entities
> > themselves.
> > > > >
> > > > > On Fri, Jun 27, 2014 at 10:05 AM, medkba <medkba@gmail.com> wrote:
> > > > >
> > > > > > Yes, i have running update statistics one of the database i.e.
> most
> >
> > > > used
> > > > > > the application
> > > > > > Run UPDATE STATISTICS LOW
> > > > > > Ok, i will read this article
> > > > > > Dosstat runs weekly once
> > > > > > This is new hp blade server with 32gb memory. It means that
> > hardware
> > > > very
> > > > > > powerful but statistics job running slow then the question aries
> > why
> > > > slow
> > > > > > and hard to convenience management to change different way of
> > running.
> > > > > > How do i check aus running
> > > > > > Thank you
> > > > > > On 27 Jun 2014 21:18, "Art Kagel" <art.kagel@gmail.com> wrote:
> > > > > >
> > > > > > > "from a shell script" wasn't what I was looking for. Are you
> > running
> > > > > plan
> > > > > > > UPDATE STATISTICS? UPDATE STATISTICS LOW? UPDATE STATISTICS
> > MEDIUM?
> > > > > > > UPDATE STATISTICS HIGH? Combinations of multiple commands? Are
> > you
> > > > > > > running these in dbaccess? If so are you running against just
> > this
> > > > one
> > > > > > > table in each command or against the entire database? Are you
> > using
> > > > my
> > > > > > > dostats utility to generate an optimal set of commands?
> > > > > > >
> > > > > > > OK, first thing to do then is to read John's paper. Link here:
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > http://www.ibm.com/developerworks/data/zones/informix/library/
> > > techarticle/miller/0203miller.html#section3
> > > > > > >
> > > > > > > Quick-and-dirty:
> > > > > > >
> > > > > > > export PDQPRIORITY=100 # Or as high as you dare without
> > disrupting
> > > > > > > production resource requirements.
> > > > > > > export PSORT_NPROCS=16 # I know the max documented is 10, trust
> > me.
> > > > > > > Make sure that you have lots of memory allocated to
> > DS_TOTAL_MEMORY
> > > > to
> > > > > > > allow for all sorting to be accomplished in memory. If you want
> > to
> > > > know
> > > > > > how
> > > > > > > much memory you will need and you haven't zero'd out your
> server
> > > > stats
> > > > > > > since the last time you tried running the update statistics (ie
> > > > onstat
> > > > > > -z)
> > > > > > > then the sysmaster:sysprofile table has a row containing the
> size
> > of
> > > > > the
> > > > > > > largest sort that's been executed in KB:
> > > > > > >
> > > > > > > select value from sysmaster:sysprofile where name =
> > 'maxsortspace';
> > > > > > >
> > > > > > > I think that I remember that you are using 11.50 so you can't
> > take
> > > > > > > advantage or LOW sampling.
> > > > > > >
> > > > > > > BTW, in another reply you said you are only runing vanilla
> UPDATE
> >
> > > > > > > STATISTICS with no modifiers. This command does not update the
> > data
> > > > > > > distributions for the table, it only updates a few columns in
> > > > > systables,
> > > > > > > syscolumns, sysfragments, and sysindices/sysindexes like nrows
> > and
> > > > > npused
> > > > > > > in systables, colmin and colmax in syscolumns, nlevels,
> nleaves,
> > > > uniq,
> > > > > > > clust, and nrows in sysindices. You need to run a combination
> of
> > LOW,
> > > > > > > MEDIUM, and HIGH on individual sets of columns to get really
> > useful
> > > > > data
> > > > > > > distributions in minimum time. If you use my dostats utility,
> as
> > do
> > > > > > > hundreds of Informix sites, it will take care of that for you.
> > > > > > >
> > > > > > > BTW, have you disabled Auto Update Statistics (AUS)? Because if
> > not
> > > > > then
> > > > > > > AUS is running every night updating stats for you (almost as
> well
> > as
> > > > > > > dostats would) so you should not have to be running update
> > statistics
> > > > > > > manually (or from cron) anyway.
> > > > > > >
> > > > > > > Art
> > > > > > >
> > > > > > > Art S. Kagel, Principal Consultant
> > > > > > > ASK Database Management
> > > > > > >
> > > > > > > Blog: http://informix-myview.blogspot.com/
> > > > > > >
> > > > > > > Disclaimer: Please keep in mind that my own opinions are my own
> > > > > opinions
> > > > > > > and do not reflect on the IIUG, nor any other organization with
> > > > which I
> > > > > > am
> > > > > > > associated either explicitly, implicitly, or by inference.
> > Neither do
> > > > > > > those opinions reflect those of other individuals
> affiliatedwith
> > any
> > > > > > > entity with which I am affiliated nor those of the entities
> > > > themselves.
> > > > > > >
> > > > > > > On Fri, Jun 27, 2014 at 8:48 AM, medkba <medkba@gmail.com>
> > wrote:
> >
> > > > > > >
> > > > > > > > Running from cron jobs daily from shell script
> > > > > > > > Not using PDQPRIORITY
> > > > > > > > 23 CPUs
> > > > > > > > 8 cpu vps is used increased from 6 to 8 no improvement
> > > > > > > >
> > > > > > > > Please let me if require more information
> > > > > > > >
> > > > > > > > Thank you very much
> > > > > > > > On 27 Jun 2014 19:43, "Art Kagel" <art.kagel@gmail.com>
> wrote:
> > > > > > > >
> > > > > > > > > How are you running update statistics for that table? What
> > > > > > environment
> > > > > > > > > variables have you set? Are you using PDQPRIORITY? What
> > engine
> > > > > > version
> > > > > > > > > and edition are you using? How many cores are on the
> machine
> > and
> > > > > how
> > > > > > > many
> > > > > > > > > CPU VPs are configured?
> > > > > > > > >
> > > > > > > > > Have you read John Miller's paper in optimizing update
> > statistics
> > > > > > runs?
> > > > > > > > >
> > > > > > > > > Art
> > > > > > > > >
> > > > > > > > > Art S. Kagel, Principal Consultant
> > > > > > > > > ASK Database Management
> > > > > > > > >
> > > > > > > > > Blog: http://informix-myview.blogspot.com/
> > > > > > > > >
> > > > > > > > > Disclaimer: Please keep in mind that my own opinions are my
> > own
> > > > > > > opinions
> > > > > > > > > and do not reflect on the IIUG, nor any other organization
> > with
> > > > > > which I
> > > > > > > > am
> > > > > > > > > associated either explicitly, implicitly, or by inference.
> > > > Neither
> > > > > do
> > > > > > > > > those opinions reflect those of other individuals
> affiliated
> > with
> > > > > any
> > > > > > > > > entity with which I am affiliated nor those of the entities
> > > > > > themselves.
> > > > > > > > >
> > > > > > > > > On Fri, Jun 27, 2014 at 3:30 AM, medkba <medkba@gmail.com>
> > > > wrote:
> > > > > > > > >
> > > > > > > > > > Hi All,
> > > > > > > > > >
> > > > > > > > > > I am having one table and contains data 23326189 and
> taking
> >
> > > > about
> > > > > > 15
> > > > > > > > mins
> > > > > > > > > > to complete update statistics
> > > > > > > > > >
> > > > > > > > > > Is there any opportunities to minimize this time?
> > > > > > > > > >
> > > > > > > > > > thank you very much
> > > > > > > > > >
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> >
> > > > > > > > > > Forum Note: Use "Reply" to post a response in the
> > discussion
> > > > > forum.
> > > > > > > > > >
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> > > > > > > > > Forum Note: Use "Reply" to post a response in the
> discussion
> > > > forum.
> > > > > > > > >
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> > > > > > > > --089e0158b87c65336e04fcd0b829
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> > > > > > > > Forum Note: Use "Reply" to post a response in the discussion
> > forum.
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> > > > > > > --089e01182b54c5879104fcd123c5
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> > > > > > > Forum Note: Use "Reply" to post a response in the discussion
> > forum.
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> > > > > Forum Note: Use "Reply" to post a response in the discussion forum.
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> > > > --001a1132edec24236a04fcd34826
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> > > > Forum Note: Use "Reply" to post a response in the discussion forum.
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> > > --001a11c34198a6cf4d04fcd3af97
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