Tags for optimizer
Identifying Used, Unused and Missing Statistics
By Rama.Korlapati, 08 Jan 2015 | 32 comments
New DBQL logging options USECOUNT and STATSUSAGE, introduced in Teradata Database 14.10, enable the logging of used and missing statistics.  The output of this logging can be utilized to find used, unused, and missing statistics globally (for all queries) or for just a subset of queries.
statistics optimizer v_database
Automated Statistics Management
By STarnow, 12 Jun 2014
Managing Teradata Optimizer statistics can be labor intensive and error prone. Many users struggle to know what columns and indexes to collect statistics on, how to detect and prevent statistics from becoming stale, and how to know if collected statistics are being used.
optimizer statistics Stats Manager TDStats
Optimizer confidence level and understanding explain plan
By ramnathjk, 15 Apr 2014 | 2 comments
Hi Guys,   I have a doubt regarding the confidence levels of the optimizer in the explain plan.   Below is the scenario that i created: 1. Created 2 tables Location and Employee with unique primary indexes on EmpNo column  
optimizer explain plan optimizer output confidence level
Explaining the EXPLAIN – New Functionality in 14.0 & 14.10
By STarnow, 17 Mar 2014
This presentation builds on Recorded Webcast # 49911 Explaining the EXPLAIN, which did just that (if you have not viewed, please do so before watching this webcast).
explain EXPLAINing plan optimizer static dynamic
Query on Skew-Sensitivity in the TD12 above Optimizer
By Santanu84, 25 Dec 2013 | 2 comments
Hi All, I was reading Carrie's blog on skew sensitivity of TD12 optimizer.http://developer.teradata.com/database/articles/skew-sensitivity-in-the-optimizer-new-in-teradata-12  
optimizer skew database
Implicit and explicit castings results in a bad plan
By TROWKRO, 23 Jul 2013 | 4 comments
Hi. I've created a very small table to illustrate the issue, I'ld like to hear opinions about. CREATE MULTISET TABLE Table_1 ,NO FALLBACK , NO BEFORE JOURNAL, NO AFTER JOURNAL, CHECKSUM = DEFAULT, DEFAULT MERGEBLOCKRATIO ( Textfield CHAR(20) CHARACTER SET LATIN NOT CASESPECIFIC )
Bad plan casting optimizer
Outer Joins and Optimizer Issues
By wpitterl, 25 Jun 2013 | 1 comment
Hi all,   I'm having some performance issues due to the way certain queries are being processed by the optimizer. I have a set of views that I want to join together, and each of these views has the same JOIN/WHERE clause combination:SELECT ...
left outer join outer join optimizer optimizer plans view view definition join insider view join performance join filtering security table security view
PMON shows a sensible "estimated time" but 'infinite' actual time.
By Boulderman, 21 Dec 2012
You would expect the other way around .... Optimizer can make estimates that are thrown off the real count based on so many factors. I dont recollect seeing this kind of situation before - I am on v13 . 
optimizer pmon estimates
Index stats vs Column stats combo , Multicolumn stats and judicious stats collection strategy
By Boulderman, 15 Dec 2012 | 2 comments
Good Day Folks... 3 Q's bunched up on stats ... <> When should you collect Index stats  and column stats for the component columns , both as against just Index stats. How does index stats help and how does stats on component columns that make up the Ix help 
statistics optimizer index cpu columns collection
Huge Cardinality estimates for TIMESTAMP COLUMNS
By m.tahoon, 12 Jul 2012 | 7 comments
estimated cardinality for the following predicate towards timestamp column is far too high vs date column 1) Table DDL: --------------------------------------
optimizer timestamp cardinality timestamp column

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