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Long time of execution when change from unicode to nonunicode

  • May 13, 2011 at 4:31 pm

    #239532

    Hi everybody, I has a table 'SO287D' with fields unicode and I has created a table 'SO287D_N' with equal structure but with fields nonunicode. When I execute a script with SO287D, the execution time is 3min but when execute with 'SO287D_N' the time is so so long.

    There is some relation between data type unicode/nonunicode and execution time?

    Thanks by your help!

  • May 13, 2011 at 5:25 pm

    #1324586

    Yes, there is a relationship. If you are comparing Unicode values to Non-Unicode values the Non-Unicode values undergo what's called an "Implicit Data Type Conversion" (IDTC). An IDTC can negate the use of indexes, cause scans and spike CPU usage if comparing large data sets or Unicode to Non-Unicode data. Your script probably needs to be reviewed to make sure that all comparisons between variables & columns are of the same data type.

    There are no special teachers of virtue, because virtue is taught by the whole community.
    --Plato

  • May 13, 2011 at 5:32 pm

    #1324587

    Thanks! I going to looking for more information about IDTC and will change the comparisons where are different the type of data (unicode/nonunicode).

    You has give a light!

  • May 14, 2011 at 2:36 am

    #1324610

    Lisset (5/13/2011)

    Hi everybody, I has a table 'SO287D' with fields unicode and I has created a table 'SO287D_N' with equal structure but with fields nonunicode. When I execute a script with SO287D, the execution time is 3min but when execute with 'SO287D_N' the time is so so long.

    There is some relation between data type unicode/nonunicode and execution time?

    Thanks by your help!

    Might also be of benefit to ensure that your new table has the "same" indexes (and perhaps statistics) on it as the old table.

  • May 14, 2011 at 8:03 am

    #1324628

    diamondgm (5/14/2011)

    Might also be of benefit to ensure that your new table has the "same" indexes (and perhaps statistics) on it as the old table.

    That is definitely a good thing to check...I took that part for granted based on "equal structure" from the original post.

    There are no special teachers of virtue, because virtue is taught by the whole community.
    --Plato

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