Updating statistics

[Sky Fly]

Hello all,

I've written a stored procedure which runs OK for the
first few thousand records it processes, then around
about the 10,000th record it suffers a sudden and dramatic
drop in performance (from about 40 records per second to
about 1 per second).

I've found that when this happens, if I run an UPDATE STATISTICS
query on the affected tables, performance picks up again,
which is good. However, this is a query that will be
running unattended, so I thought that I good idea would
be to put the UPDATE STATISTICS statement in the stored
procedure and have it run after about eight thousand records
have been processed.

However, I find that even though the statement is run
after the 8,000th record, the performance drop *still*
occurs after the 10,000th record. I find this odd because
the statistics have just recently been updated. Is there
anything else I should be looking at?

TIA,

--
Akin

aknak at aksoto dot idps dot co dot uk

[Uri Dimant]

Re: Updating statistics

Sky
Have you looked at execution plan of the query? Does the query optimizer
available to use indexes which defined on the table?


"Sky Fly" <nobody@blackho le.com> wrote in message
news:c6f9t6$b6n 8j$1@ID-18325.news.uni-berlin.de...[color=blue]
> Hello all,
>
> I've written a stored procedure which runs OK for the
> first few thousand records it processes, then around
> about the 10,000th record it suffers a sudden and dramatic
> drop in performance (from about 40 records per second to
> about 1 per second).
>
> I've found that when this happens, if I run an UPDATE STATISTICS
> query on the affected tables, performance picks up again,
> which is good. However, this is a query that will be
> running unattended, so I thought that I good idea would
> be to put the UPDATE STATISTICS statement in the stored
> procedure and have it run after about eight thousand records
> have been processed.
>
> However, I find that even though the statement is run
> after the 8,000th record, the performance drop *still*
> occurs after the 10,000th record. I find this odd because
> the statistics have just recently been updated. Is there
> anything else I should be looking at?
>
> TIA,
>
> --
> Akin
>
> aknak at aksoto dot idps dot co dot uk
>
>[/color]

[Sky Fly]

sp_sqlagent_get _perf_counters (was: Updating statistics)

OK,

I think I've found out what's causing the problem. After examining
a trace I ran on the db, I found out that at the times when the
performance drops, a system stored procedure - sp_sqlagent_get _perf_counters
- is running.

What I would like to know is: what does this sp do? Why does it run?
Is it safe to stop it or prevent it from running on occasion?
How do I do this?

TIA,

--
Akin

aknak at aksoto dot idps dot co dot uk

"Uri Dimant" <urid@iscar.co. il> wrote in message
news:u9nlCHoKEH A.2692@tk2msftn gp13.phx.gbl...[color=blue]
> Sky
> Have you looked at execution plan of the query? Does the query optimizer
> available to use indexes which defined on the table?
>
>
> "Sky Fly" <nobody@blackho le.com> wrote in message
> news:c6f9t6$b6n 8j$1@ID-18325.news.uni-berlin.de...[color=green]
> > Hello all,
> >
> > I've written a stored procedure which runs OK for the
> > first few thousand records it processes, then around
> > about the 10,000th record it suffers a sudden and dramatic
> > drop in performance (from about 40 records per second to
> > about 1 per second).
> >
> > I've found that when this happens, if I run an UPDATE STATISTICS
> > query on the affected tables, performance picks up again,
> > which is good. However, this is a query that will be
> > running unattended, so I thought that I good idea would
> > be to put the UPDATE STATISTICS statement in the stored
> > procedure and have it run after about eight thousand records
> > have been processed.
> >
> > However, I find that even though the statement is run
> > after the 8,000th record, the performance drop *still*
> > occurs after the 10,000th record. I find this odd because
> > the statistics have just recently been updated. Is there
> > anything else I should be looking at?
> >
> > TIA,
> >
> > --
> > Akin
> >
> > aknak at aksoto dot idps dot co dot uk
> >
> >[/color]
>
>[/color]

[Uri Dimant]

Re: sp_sqlagent_get _perf_counters (was: Updating statistics)

Sky
By running this stored procedure SQLAgent is determined if there are any
thresholds changed for
the alerting system. However you can change the interval by editing registry
key. ( May be danger)
HKEY_LOCAL_MACH INE\SOFTWARE\Mi crosoft\Microso ft SQL
Server\Server_N ame\SQLServerAg ent\Performance SamplingInterva l


"Sky Fly" <nobody@blackho le.com> wrote in message
news:c6g5g2$blu q1$1@ID-18325.news.uni-berlin.de...[color=blue]
> OK,
>
> I think I've found out what's causing the problem. After examining
> a trace I ran on the db, I found out that at the times when the
> performance drops, a system stored procedure -[/color]
sp_sqlagent_get _perf_counters[color=blue]
> - is running.
>
> What I would like to know is: what does this sp do? Why does it run?
> Is it safe to stop it or prevent it from running on occasion?
> How do I do this?
>
> TIA,
>
> --
> Akin
>
> aknak at aksoto dot idps dot co dot uk
>
> "Uri Dimant" <urid@iscar.co. il> wrote in message
> news:u9nlCHoKEH A.2692@tk2msftn gp13.phx.gbl...[color=green]
> > Sky
> > Have you looked at execution plan of the query? Does the query optimizer
> > available to use indexes which defined on the table?
> >
> >
> > "Sky Fly" <nobody@blackho le.com> wrote in message
> > news:c6f9t6$b6n 8j$1@ID-18325.news.uni-berlin.de...[color=darkred]
> > > Hello all,
> > >
> > > I've written a stored procedure which runs OK for the
> > > first few thousand records it processes, then around
> > > about the 10,000th record it suffers a sudden and dramatic
> > > drop in performance (from about 40 records per second to
> > > about 1 per second).
> > >
> > > I've found that when this happens, if I run an UPDATE STATISTICS
> > > query on the affected tables, performance picks up again,
> > > which is good. However, this is a query that will be
> > > running unattended, so I thought that I good idea would
> > > be to put the UPDATE STATISTICS statement in the stored
> > > procedure and have it run after about eight thousand records
> > > have been processed.
> > >
> > > However, I find that even though the statement is run
> > > after the 8,000th record, the performance drop *still*
> > > occurs after the 10,000th record. I find this odd because
> > > the statistics have just recently been updated. Is there
> > > anything else I should be looking at?
> > >
> > > TIA,
> > >
> > > --
> > > Akin
> > >
> > > aknak at aksoto dot idps dot co dot uk
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]

[Sky Fly]

Re: sp_sqlagent_get _perf_counters (was: Updating statistics)

Hello Uri,

I tried changing this setting in the registry to 0; I tried changing
it to a very large value; I tried deleting the alerts in EM;
all made no difference.

So I've decided that I will call update statistics every 10 seconds
or so. This appears to minimise the original problem, but I don't
know if it will have any effect on the performance of the database.
Can you advise?

"Uri Dimant" <urid@iscar.co. il> wrote in message
news:uAguObrKEH A.808@tk2msftng p13.phx.gbl...[color=blue]
> Sky
> By running this stored procedure SQLAgent is determined if there are any
> thresholds changed for
> the alerting system. However you can change the interval by editing[/color]
registry[color=blue]
> key. ( May be danger)
> HKEY_LOCAL_MACH INE\SOFTWARE\Mi crosoft\Microso ft SQL
> Server\Server_N ame\SQLServerAg ent\Performance SamplingInterva l
>
>
> "Sky Fly" <nobody@blackho le.com> wrote in message
> news:c6g5g2$blu q1$1@ID-18325.news.uni-berlin.de...[color=green]
> > OK,
> >
> > I think I've found out what's causing the problem. After examining
> > a trace I ran on the db, I found out that at the times when the
> > performance drops, a system stored procedure -[/color]
> sp_sqlagent_get _perf_counters[color=green]
> > - is running.
> >
> > What I would like to know is: what does this sp do? Why does it run?
> > Is it safe to stop it or prevent it from running on occasion?
> > How do I do this?
> >
> > TIA,
> >
> > --
> > Akin
> >
> > aknak at aksoto dot idps dot co dot uk
> >
> > "Uri Dimant" <urid@iscar.co. il> wrote in message
> > news:u9nlCHoKEH A.2692@tk2msftn gp13.phx.gbl...[color=darkred]
> > > Sky
> > > Have you looked at execution plan of the query? Does the query[/color][/color][/color]
optimizer[color=blue][color=green][color=darkred]
> > > available to use indexes which defined on the table?
> > >
> > >
> > > "Sky Fly" <nobody@blackho le.com> wrote in message
> > > news:c6f9t6$b6n 8j$1@ID-18325.news.uni-berlin.de...
> > > > Hello all,
> > > >
> > > > I've written a stored procedure which runs OK for the
> > > > first few thousand records it processes, then around
> > > > about the 10,000th record it suffers a sudden and dramatic
> > > > drop in performance (from about 40 records per second to
> > > > about 1 per second).
> > > >
> > > > I've found that when this happens, if I run an UPDATE STATISTICS
> > > > query on the affected tables, performance picks up again,
> > > > which is good. However, this is a query that will be
> > > > running unattended, so I thought that I good idea would
> > > > be to put the UPDATE STATISTICS statement in the stored
> > > > procedure and have it run after about eight thousand records
> > > > have been processed.
> > > >
> > > > However, I find that even though the statement is run
> > > > after the 8,000th record, the performance drop *still*
> > > > occurs after the 10,000th record. I find this odd because
> > > > the statistics have just recently been updated. Is there
> > > > anything else I should be looking at?
> > > >
> > > > TIA,
> > > >
> > > > --
> > > > Akin
> > > >
> > > > aknak at aksoto dot idps dot co dot uk
> > > >
> > > >
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]