#DateWhereItemComment
4508 Sep 2010 @ 02:46 PDTcarrie's blogRejection CAN be RewardingI think your point is a good one. You have to look at the estimates that the optimizer is producing for the category of queries that you would like to reject, if you plan to base rejection on est...
4403 Sep 2010 @ 04:11 PDTcarrie's blogPenalty Box Over-Population You could split a single penalty box into two or more penalty boxes, but if you are still using CPU limits on all of them, you may end up with similar issues if you are not aware of how many concur...
4330 Aug 2010 @ 08:02 PDTcarrie's blogPenalty Box Over-Population Hi Dave, Glad you agree. Thanks for commenting. I did do an earlier post called "rejection can be rewarding" that confirms your viewpoint that some queries are "too bad to run". It's at htt...
4226 Aug 2010 @ 08:13 PDTcarrie's blogPenalty Box Over-Population Managing the level of concurrency in a penalty box is a very good idea. If queries classified directly into a penalty box workload, you could indeed set up a query limit on the workload and keep c...
4113 Aug 2010 @ 03:26 PDTcarrie's blogIf You’re Not Collecting Statistics on Your Dictionary Tables, Do It. Now.Hi Ian, Whether or not stats will help on your dictionary tables will depend on whether doing so improves your query plans, or doesn’t. If you're users are not doing complex queries against d...
4030 Jul 2010 @ 08:39 PDTcarrie's blogCPU Limits at Multiple LevelsSorry, I missed that April question, so let me respond to that first. Anytime a CPU limit is changed, whether manually by the DBA, or automatically by TASM, all active work that is under the ...
3926 Jul 2010 @ 10:44 PDTcarrie's blogCollecting Stats on PARTITION for NON-PARTITIONED tables Hi Kevin, You bring up a good point. As mentioned above, from 12.0.3 onwards PARTITION statistics on a table (if they exist) are used to estimate table cardinality for good extrapolation, ev...
3823 Jul 2010 @ 08:39 PDTcarrie's blogIf You’re Not Collecting Statistics on Your Dictionary Tables, Do It. Now.Hi Tony. Good question. A new access right called "STATISTICS" was introduced in Teradata 13.0. This right can be granted to other users on DBC tables which enables them to collect stats.
3714 Jul 2010 @ 09:48 PDTcarrie's blogCollecting Stats on PARTITION for NON-PARTITIONED tables The target table receives a table level lock, based on your explain information above. Pseudo table lock which is applied at the row hash level is something different, it not a base table lock. F...
3612 Jul 2010 @ 11:19 PDTcarrie's blogCrossing NUSI Update Contention Off Your Watch ListPlease replace the last paragraph in the above text (which is outdated information) with the following text: Enhancements made in V2R6.2 improved the performance of rollbacks on a table with a N...
3512 Jul 2010 @ 11:11 PDTcarrie's blogCollecting Stats on PARTITION for NON-PARTITIONED tables Hi Bodhi, When you say "different load jobs" do you mean different TPump jobs? Locking conflicts will be different depending on the type of load approach you are intending to use. Only TPump ...
3430 Jun 2010 @ 08:41 PDTcarrie's blogIf You’re Not Collecting Statistics on Your Dictionary Tables, Do It. Now.The advantage you will get from collecting stats on the dictionary tables will depend on whether you are submitting SQL of any complexity against those DBC tables. Such SQL could be coming from 3r...
3318 Jun 2010 @ 09:36 PDTcarrie's blogExpedite Your Tactical Queries, Whether You Think They Need It or NotHi Robert, For you first question, it is not uncommon for sites to add additional AWTs/AMP to add back in some of the AWTs that were taken out of the general pool for use by the new tactical re...
3215 Jun 2010 @ 08:42 PDTDatabaseStatistics Collection Recommendations for Teradata 12Hi Jack, The fact that you are getting "no confidence" in your explain text AFTER collecting statistics makes me think that you might have missed some important statistics. In addition to coll...
3114 Jun 2010 @ 08:48 PDTcarrie's blogIf You’re Not Collecting Statistics on Your Dictionary Tables, Do It. Now.Hi Shrinivas, If you look at the explain of a collect statistics statement, the database applies an access lock on the table on which statistics are being collected. This is to minimize any blo...
3008 Jun 2010 @ 09:16 PDTcarrie's blogSome Rules are Meant to be Broken: Things that Don't Obey CPU Limits I am not sure that I am correctly reading your question. Please let me know if I have mis-interpreted what you are asking. Whether or not a system is in flow control will not impact how CPU lim...
2927 May 2010 @ 02:38 PDTcarrie's blogExpedite Your Tactical Queries, Whether You Think They Need It or NotIt sounds like you are considering throttles to control the concurrency of the non-tactical work. Many sites do find throttles to be valuable for this purpose. Reserved AMP worker tasks is also a ...
2821 May 2010 @ 01:28 PDTcarrie's blogMore on ResUsageSAWT When Collection and Logging Rates DifferAwtInuseMax gives you the maximum AWT count from all the AMPs in the node. Please refer to my example above.
2720 May 2010 @ 02:24 PDTcarrie's blogTips on using Sampled StatsHi Meenakshi, There are two questions here: WHY DO YOU NEED PPI FOR A UPI TABLE? A unique PI controls data distribution, prevents duplicates, and allows you to access a table directly and ...
2618 May 2010 @ 01:46 PDTcarrie's blogMore on ResUsageSAWT When Collection and Logging Rates DifferYou are correct: If logging/collect interval the same, AwtInuse should never be greater than AwtInuseMax. You never want to divide a max column in any ResUsage table by CollectIntervals. The m...
2514 May 2010 @ 08:27 PDTcarrie's blogMore on ResUsageSAWT When Collection and Logging Rates DifferIn the article, when I talked about softening due to averaging, I was talking about the situation where the logging and collect intervals were different. In that case you would have to divide the ...
2411 May 2010 @ 05:01 PDTDatabaseStatistics Collection Recommendations for Teradata 12Aa, There is no method that I am aware of for getting index recommendations from out of the explain. There is a tool that is part of the Teradata Analyst Pack that you could use for that purpos...
2311 May 2010 @ 05:00 PDTDatabaseStatistics Collection Recommendations for Teradata 12Hari, Please share this information with your team if you think it will be useful to them. I am glad to hear you found it helpful. Thanks so much, -Carrie
2230 Mar 2010 @ 08:10 PDTcarrie's blogCPU Limits at Multiple LevelsTo learn about Teradata, see the courses offered via the Teradata Education Network at www.teradata.com/t/TEN.
2109 Mar 2010 @ 10:57 PSTDatabaseStatistics Collection Recommendations for Teradata 12To learn about Teradata, see the courses offered via the Teradata Education Network at www.teradata.com/t/TEN. To learn about the Teradata Certified Professional Program, see the TCPP website at...

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