#DateWhereItemComment
14502 Jul 2012 @ 01:31 PDTcarrie's blogAutomated Demotions on the Appliance: What are Query Milestones?You can only change the priority (by changing the account string) of a running query if you are NOT using TASM. On the appliance platform you are not using TASM, so it would seem to me that you s...
14428 Jun 2012 @ 03:57 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations Thanks, Neil!
14318 Jun 2012 @ 08:32 PDTDatabaseTo Peek or Not to Peek, That is the QuestionRichard, You will see A (Always specific) as the cache flag for a query if the optimizer determines through its previously saved metrics that the specific plan (S the first time) produces a bet...
14211 Jun 2012 @ 09:32 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations Pinal, Different cost profiles can have an impact on optimizer estimates. However, I do not have any direct experience trying out different cost profiles, so I am not able to make a recommenda...
14106 Jun 2012 @ 08:15 PDTcarrie's blogUtility Session Management - It's Inside the Database in Teradata 13.10! (UPDATED)Hi Bob, If you are using TASM, it is recommended that you use TASM utility throttle to manage concurrency of load jobs. TENACITY and SLEEP will be ignored if the load job is under the control of...
14006 Jun 2012 @ 08:11 PDTcarrie's blogControlling the Flow of Work in TeradataCPU seconds consumed by a query is reported in DBQL (Database Query Log). It is reported in both AMP CPU seconds and Parser CPU seconds. See the DBQL chapter in the Database Administration manual...
13904 Jun 2012 @ 08:08 PDTcarrie's blogSimplifying AMP Worker Task Monitoring and Getting it RightThe number of AWTs used by load jobs is easy to predict and you don't need to look at Reusage data. For each load job, here is what will be used: FastLoad or TPT Load Operator: Phase I: ...
13801 Jun 2012 @ 08:52 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations Hi Bill, Good question. That limit has already been lifted. In 14.0 you may define up to 512 single or multicolumn statistics. Thanks, -Carrie
13729 May 2012 @ 03:15 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations Please note: This posting was updated on May 29, 2012, to reflect more accurate information on dynamic AMP sampling.
13629 May 2012 @ 11:37 PDTcarrie's blogControlling the Flow of Work in TeradataHi Pinal, In order to address your comments, I have put out a new blog posting that addresses flow control for spawned messages and how that all works. Please see my latest blog posting, and ...
13522 May 2012 @ 08:07 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations For your point #1, if all your queries against a table are always and only going to do a full table scan and never join to other tables, then you are correct that collecting statistics on predicate...
13415 May 2012 @ 01:23 PDTDatabaseSkew-Sensitivity in the Optimizer: New in Teradata 12Thank you for your kind words! As you probably already know, you can always look at explain text after a query runs (or before ), seeking out steps with large row redistributions. DBQLStepTbl ...
13310 May 2012 @ 01:43 PDTcarrie's blogAutomated Demotions on the Appliance: What are Query Milestones?Vasu, You are not able to set or change CPU limits on the appliance platforms. If you are on a platform with full TASM and were on 13.10, you would use Viewpoint Workload Designer to set C...
13210 May 2012 @ 01:36 PDTcarrie's blogGlobal Temp Tables with Tactical Applications?There are a couple of considerations here. First, if NOT having cached plans (you won't get cached plans using GTTs) is NOT causing you performance issues, then there is probably no need to chan...
13104 May 2012 @ 07:58 PDTcarrie's blogHow to set a System-Level CPU limit for Capacity-on-DemandThe CPU limit has nothing to do with the relative weight that is used by the different allocation groups. The CPU limit is a ceiling that limits how much CPU can be used by the RP or AG. You onl...
13004 May 2012 @ 07:57 PDTcarrie's blogAutomated Demotions on the Appliance: What are Query Milestones?If the query milestone is removed, then that means that no query will get it's priority diminished once it has started to run. All queries will run at their original priority until they complete. ...
12927 Apr 2012 @ 04:25 PDTcarrie's blogAutomated Demotions on the Appliance: What are Query Milestones?Vasudev, The appliance platforms are intended to be simple, easy to use, with few knobs to turn or decisions to make. For that reason, you cannot change priority settings using any of the vari...
12826 Apr 2012 @ 08:10 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations Speaking of the resources the collect stats operations can use, there are some enahncements available in Teradata 14.0 that will reduce that. In Teradata 14.0 performance improvements to stats c...
12723 Apr 2012 @ 08:39 PDTcarrie's blogTwo Levels of Concurrency Control for Load Utilities in Teradata 13.10Hi Raj, If you are on the appliance and you are on 13.10, you can create system throttles and/or utility throttles. Without using utility throttles there is no way to specify something less f...
12620 Apr 2012 @ 08:42 PDTcarrie's blogTwo Levels of Concurrency Control for Load Utilities in Teradata 13.10Hi Raj, Changing MaxLoadAWT to 48 and MaxLoadTasks to 12 is reasonable if that load job concurrency level is adequate for your needs. You are correct that 12 FastLoads all in phase I will use 3...
12516 Apr 2012 @ 09:27 PDTDatabaseSkew-Sensitivity in the Optimizer: New in Teradata 12I cannot tell you for sure that missing stats are contributing to skewed processing you are experiencing. Under some circumstances more fully collecting statistics provides the optimizer with more...
12413 Apr 2012 @ 11:23 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations PLEASE NOTE: A small change was made to the above text on April 13, to add this new bullet under the "Collect full statistics" list. It was left out in the original posting: • Single-colum...
12313 Apr 2012 @ 11:21 PDTcarrie's blogTeradata 13.10 Statistics Collection Recommendations The new default limit for the size of the histogram values fields is 25 bytes in Teradata 14.0. However, the limit can be increased by specifying a greater value on the COLLECT STATISTICS statemen...
12211 Apr 2012 @ 04:10 PDTDatabaseSkew-Sensitivity in the Optimizer: New in Teradata 12Without stats collected on the join columns, the optimizer assumes that the table with a small number of distinct values on the join columns will have a complete match. If there is not a complete ...
12111 Apr 2012 @ 04:06 PDTDatabaseStatistics Collection Recommendations for Teradata 12You do not necessarily need to recollect statistics on columns unrelated to partitioning at the same time as you recollect on PARTITON and the partitioning columns. However, if the entire table has...

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