Home Forums Article Discussions Article Discussions by Author Discuss Content Posted by David Poole RegEx for DBAs RE: RegEx for DBAs

  • May 8, 2012 at 8:41 am

    #1484557

    Solomon Rutzky (5/8/2012)

    Jeffrey Bijkerk (5/8/2012)

    If you use regex combined with a where clause it can not use the index anymore. I think this is very important.

    Hi Jeffrey. It is important to a degree. Sometimes you need to do queries that are not going to use an index, just like using a LIKE statement where the pattern starts with % or _. Also, not all columns are indexed. So, this alone is not a reason to not use Regular Expressions, but it is a reason to not use ANY function in some situations where performance is critical.

    Take care,

    Solomon...

    I do have to agree with Solomon here. It really does depend on how it's used. You can get some very powerful index seeks followed by the desired row scan even when wrapping some columns in the likes of ISNULL(). It very much depends on what the columns of the index and the WHERE clause are.

    --Jeff Moden

    RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
    First step towards the paradigm shift of writing Set Based code:
    ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

    Change is inevitable... Change for the better is not.

    Helpful Links:
    How to post code problems
    How to Post Performance Problems
    Create a Tally Function (fnTally)