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Message Posted: Mon, 06 Apr 2015 @ 19:23:29 GMT


     
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Subj:   Re: Updating via view concurrently
 
From:   Dave Wellman

Hi,

As pointed out, a "locking row for ..." does not necessarily mean that you get a row (or row hash) lock. You also have to have an equality constraint on the PI of the target table.

Note that an INSERT/SELECT will always place a table level write lock on the target table.

To get multiple transactions inserting rows into the same table concurrently whilst minimising lock contention you have to EITHER:

- each insert must be an INSERT VALUES command (i.e. insert a single row),

OR

- have the data values outside of Teradata (e.g. in a file) so that each individual request processes a single row hash of the target table.


Cheers,

Dave

Ward Analytics Ltd - Information in motion (www.ward-analytics.com)



     
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