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NASCAR9
Intermediate
Joined: 08 Oct 2004
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Location: California
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 Posted: Wed Aug 26, 2015 11:27 am Post subject: RUNSTATS DB2 10 z/OS |
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Our shop runs Runstats on a regular basis. When writing queries in Data Studio and running them thru the analyzer it sometimes recommends new Runstats to make the query efficient.
My question is: Does the recommended Runstats overlay the shop created Runstats? Or does it create an additional Runstat to use until the next Batch Production job runs?
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kolusu
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Joined: 26 Nov 2002
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Location: San Jose
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| Posted: Wed Aug 26, 2015 1:25 pm Post subject: Re: RUNSTATS DB2 10 z/OS |
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| NASCAR9 wrote: | | My question is: Does the recommended Runstats overlay the shop created Runstats? Or does it create an additional Runstat to use until the next Batch Production job runs? |
Nascar9,
How exactly is your shop creating the run stats? Are you physically updating the sysibm tables with the latest information?
When you run the Utilities like REORG the runstats gets updated. However if you are doing a lot of inserts and deletes programmatically you might end up having a bad stats.
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Kolusu
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NASCAR9
Intermediate
Joined: 08 Oct 2004
Posts: 274
Topics: 52
Location: California
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| Posted: Wed Aug 26, 2015 1:45 pm Post subject: |
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kolusu,
The batch job runs the runstats based on a query to determine if they need to be run. Yes they update the sysibm tables. We are also using Real Time Statistics.
I'm asking because I get asked to run many queries that pull large amounts data, joining to many tables. I also try and use indexes when possible. Sometimes that's not possible.
Before I run any large query, I always run it thru the Data Studio Optimizer. The Optimizer will sometimes give suggestions for additional statistics. I'm just trying to make sure I'm not destroying Production Stats running my suggested stats.
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kolusu
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Joined: 26 Nov 2002
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| Posted: Wed Aug 26, 2015 2:25 pm Post subject: |
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NASCAR9,
Unless you are updating the sysibm tables via Data studio optimizer, I don't think the suggested stats are overlaying the contents. How about you do a simple test and take the run stats values before you run your query and also after you run your query which does have the suggested stats.
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Kolusu
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NASCAR9
Intermediate
Joined: 08 Oct 2004
Posts: 274
Topics: 52
Location: California
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| Posted: Thu Aug 27, 2015 10:38 am Post subject: |
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kolusu,
I did what you suggested in the TEST DB.
1. In Data Studio I checked the Timestamp for the indexes for the table.
2. I ran the recommended statistics.
3. Refreshed my Index list in Data Studio and checked the Timestamps again.
They didn't change.
If anyone has a query to list the statistics for a particular table/table space please post it.
Still not 100% positive I want to do this in Production. The query may ease my mind.
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