How to detriment if your sample statistics is suitable

To detriment if your sample statistics is or not (TD 12) you may need to make a HELP STATISTICS statement on you table or column twice, one with full stats and the other after applying the sampling and see the difference

1- To make a help stats on table level:

HELP STATISTICS "tablename";


2- To make a help stats on Column level:

HELP STATISTICS "tablename" Column "columnname";

Collect Statistics using sample in TD 12

There is a new feature in TD 12 that you can specify the sample percent you need before running collect stat.

You can do it on the,

1- session level:

DIAGNOSTIC "COLLECTSTATS, SAMPLESIZE=20" ON FOR SESSION;

The above statment means that all collect stats starment with "USING SAMLE" keyword in the session will be collected with 20% (You can change it to what is suitable for your tables).

2- Request level:

DIAGNOSTIC "COLLECTSTATS, SAMPLESIZE=20" ON FOR REQUEST;

That's means it will applyed only on the next collect statment that follows the diagnostic statment.

How to clean / Purge DBQL Tables

delete from DBC.DBQLObjTbl Where CollectTimeStamp < '2009-10-01 00:00:00';
delete from DBC.DBQLogTbl where LogonDateTime < '2009-10-01 00:00:00';
delete from DBC.DBQLSqlTbl Where CollectTimeStamp < '2009-10-01 00:00:00';
delete from DBC.DBQLExplainTbl where CollectTimeStamp < '2009-10-01 00:00:00';
delete from DBC.DBQLStepTbl Where CollectTimeStamp < '2009-10-01 00:00:00';
delete from DBC.DBQLSummaryTbl where CollectTimeStamp < '2009-10-01 00:00:00';

Welcome to my teradata world !!

This is my first words in my new Teradata blog,

Actually i worked for a years as Teradata Database Administrator (DBA) and had a lot of experience, problem solving and tips and tricks in Teradata administration on going

I believe that we have to share our knowledge for all as the knowledge in increasing when your share it and decreasing when your keep it for your self

I will do my best to put all my knowledge on your hands.

and I hope that being useful for you

Mahmoud Karam, PMP, Teradata Certified Master