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Why the time of masking of 2 similar tables differs so much?


I have 2 tables A and B to mask, I am masking a single column using a substitution rule in each table with random 9 digits (%n%n%n%n%n%n%n%n%n). Table A has 180_000 rows and 38 columns; table B has 100_000 rows and 33 columns. Neither of them has triggers. Masking of A takes about 2 hours, masking of B takes about 1 minute. Could you please advise why it takes 120 times longer to mask table A that it takes to mask table B, and how it could be optimized.

Thank you,


  • Options
    Eddie DEddie D Posts: 1,788 Rose Gold 5
    Hi Constantine, thank you for your forum post.

    Does the advice in this help article, answer your question on how to optimize your substitution rule?

    Many Thanks
    Eddie Davis
    Senior Product Support Engineer
    Redgate Software Ltd
    Email: support@red-gate.com
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    ConstantineConstantine Posts: 2 New member
    edited May 9, 2019 6:07PM
    Hi Eddie, 

    Thank you for your response. I have reread the article and made some changes to the table structure adding an identity column. Now it runs very fast.

    Thank you again,

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