Submitted Questions

  • What is the difference between Global temporary tables and Volatile temporary tables?

    Global Temporary tables (GTT) -1. When they are created, its definition goes into Data Dictionary.2. When materialized data goes in temp space.3. thats why, data is active upto the session ends, and definition will remain there upto its not dropped using Drop table statement.If dropped from some other session then its should be Drop table all;4. you can collect stats on GTT.Volatile Temporary tables...

    Bikhayat kumar

    • Feb 10th, 2014

    GTT takes up space from temporary space where as VTT takes up space from spool. GTT survive TD system restarts where as VTT does not. GTT allows index to be created where as VTT does not. In a sing...

    Prashant Nile

    • Dec 13th, 2013

    GTT uses the Temp Space where as Volatile table use the Spool Space. Both are Session Based once you logged of Data gets vanished. For GTT Definitions remains as it is, as it gets stored in Data Di...

  • How teradata makes sure that there are no duplicate rows being inserted when its a SET table?

    Teradata will redirect the new inserted row as per its PI to the target AMP (on the basis of its row hash value), and if it find same row hash value in that AMP (hash synonyms) then it start comparing the whole row, and find out if duplicate.If its a duplicate it silently skips it without throwing any error.Cheers,Shilpa

    saurabh.gupta4u

    • Feb 6th, 2009

    When the target table has UPI then the Row hash of PI column will lead to the AMP and the duplicate row is rejected with an error.In case of a NUPI defined on a SET table the duplicate row is compared on all columns and if the entire row is dups then it is rejected without an error code > 0.