Session used by Fastexport

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Junior Supporter

Session used by Fastexport

Hi,

I have a question about the number of sessions that a fastexport uses. When i read through the fastexport manual,  came to know that in fastexport sessions parameter is optional. If no sessions parameter is specified, the default is 4 sessions. The max can be the total number of AMPS on the system.

So, my question is -

1. how to find out from the log tables, how many sessions a job has actually taken  ?

2. Is there any setting DBS/TASM that affects this ?

3. Is there any guideline to specify this fugure

Any reference to any material would really help

--samir

1 REPLY
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Teradata Employee

Re: Session used by Fastexport

  1. If you have DBQL UtilityInfo logging active, that shows the number of "special sessions" actually used. Or if you use Viewpoint rewind and look at Query Monitor "by Utility / by Job" it will show you the number of sessions including the two SQL "auxiliary" sessions in addition to the export special sessions. (Drill in to the Job to see.)
  2. Yes, TASM "Utility Sessions" will override whatever is specified in the script. The reserved UtilityDataSize queryband allows you to request "Small", "Large", or default settings, or you can set up special rules with other classification criteria instead of or in addition to UtilityDataSize.
  3. For FastExport, you nearly always will want to use 4 sessions. If you can't take advantage of 4 sessions, you probably don't need to use FastExport. For extremely large exports, you might be able to take advantage of more than four, but will rapidly reach a point of diminishing return. One per AMP is the upper limit but nearly always overkill on today's systems. An exception is if you are using TPT with many EXPORT operator instances either on a big server with lots of CPU cores / execution pipelines and high bandwidth networking, or via TPTAPI spread across a multiple-server "grid" infrastructure (as provided by some ETL tools). Then you probably want 1 or 2 sessions per instance.