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Asked: 2026-05-21T03:53:50+00:00

I’m not trying to start a debate on which is better in general, I’m

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I’m not trying to start a debate on which is better in general, I’m asking specifically to this question. 🙂

I need to write a query to pull back a list of userid (uid) from a database containing 500k+ records. I’m returning just the one field, uid. I can query either our Oracle box or our MSSQL 2000 box. The query looks like this (this has not been simplied)

select uid
from employeeRec
where uid = 'abc123'

Yes, it really is that simply of a query. Where I need the tuninig help is that the uid is indexed and some uid could be (not many but some) ‘ABC123’ or ‘abc123’. MSSQL doesn’t care of the case-sensitivity whereas Oracle does. So for Oracle, my query would look like this:

select uid
from employeeRec
where lower(uid) = 'abc123'

I’ve learned that if you use lower on an index field in MSSQL, you render the index useless (there are ways around it but that is beyond the scope of my question here – since if I choose MSSQL, I don’t need to use lower at all). I wanted to know if I choose Oracle, and use the lower() function, will that also hurt performance of the query?

I’m looping over this query about 200 times in addition to some other queries that are being run and to process the entire loop takes 1 second per iteration and I’ve narrowed down the slowness to this particular query. For a web page, 200 seconds seems like eternity. For you CF readers, timeout value has been increased so the page doesn’t error out and there are no page errors, I’m just trying to speed up this query.

Another item to note: This database is in a different city than the other queries being run so I do expect some lag time there.

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1 Answer

  1. Editorial Team

    I wanted to know if I choose Oracle,
    and use the lower() function, will
    that also hurt performance of the
    query?

    Yes. The perforamnce reduction is because the index is on the original value and the collation i case sensitive, so all possible values must be run through the function to filter out the ones matching.

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