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Madhavan 3 posts Joined 10/08
10 Nov 2008
Teradata

Hi, I am new to teradata. I have found one thing in Optimizer's explain plan. That is No residual condition. Can anybody exlain about this.. Pleaseee ..!!!!!

Kumaresh 1 post Joined 11/08
10 Nov 2008

Hi,With No Residual Conditions means..In your query whichever you are passing, there might be some conditions like filters,aggregates, or comparisons,etc. So, the optimizer is predicting this EXPLAIN plan after applying all the conditions to the dataset.-------------------------------------------------------------with no residual conditionsAll applicable conditions have been applied to the rows.-------------------------------------------------------------

young chap 27 posts Joined 01/08
11 Nov 2008

Hi madhavan,No residual condition represents the query in which u r explaining lacks any filtering conditions or in general terms its a simple select * from databasename.tablename.

Madhavan 3 posts Joined 10/08
11 Nov 2008

Thanks guys..... :)

ChrisTansey 12 posts Joined 11/08
15 Nov 2008

I'd dissagree slightly with young chap here, my understanding is that no residual conditions means just as it says. The data is extracted from the table using the conditions stated in the explain step and there are no further conditions to be added to this data extraction in later steps. It does not mean there are no conditions (sel * from databasename.tablename), just no more after those applied in the step

young chap 27 posts Joined 01/08
16 Nov 2008

Hi chris Tansey,Thanks for your inputs..this will encourage newguys to teradata like me to learn interactively..i have few doubts in my mind..as you have mentioned ''The data is extracted from the table using the conditions stated in the explain step and there are no further conditions to be added to this data extraction in later steps''. does it mean that is it possible to have further conditions to be added to this data extraction in later steps if so we wont be getting ''no residual conditions'' in such scenarios?Regards,Young chap

Fred 1096 posts Joined 08/04
16 Nov 2008

In the context of this question about EXPLAIN wording, "residual conditions" would be any additional filtering (beyond the join terms, or index access criteria, etc.) that will be applied "on the fly" during THIS step - further limiting the rows put into spool and passed along to subsequent steps.In other words, which of the remaining (residual) conditions can be applied NOW rather than waiting until a later step.

ChrisTansey 12 posts Joined 11/08
17 Nov 2008

That's it, you will occassionally see 'with some residual conditions' (wording may not be exact) where further filtering of the data selected takes place, perhaps on a join to another table.

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