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Message Posted: Tue, 04 Jan 2011 @ 12:13:32 GMT

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Hi,

Evene when Teradata accesses a table using the rowhash, it ALWAYS double-checks using the data value.

So, using your example below, assume that your query was:

     Sel *
     From table
     Where column = 1254;

Initially both rows would be found, based on row hash, but then the data value is checked and only the row with the correct data value is used in subsequent processing.

The uniqueness value is not visible to user sql, it is mainly used internally by the dbms so that every single row can be uniquely identified.

Largely forget about it.

Cheers,

Dave

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

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