Greetings:
I am trying to understand the difference in the performance of a SELECT
statement by using variations when referencing a column with an AND
qualifier.
Note: SMRYFLAG is a TEXT 1 field and has 4 possible values: E, M, N or O.
Specifically if I issue the following query and state SMRYFLAG = 'M'
performance of the SELECT statement is dismal:
SELECT * FROM DALY_PROC_VIEW WHERE PRODDATE BETWEEN 07/01/2002 AND
09/30/2002 AND GRADE='1233' AND SMRYFLAG = 'M' ORDER BY
PRODDATE,CUR_CC,GRADE
However, if I use any of the following variations I get almost instant
results which, of course, is what I'm after.
This works well: SMRYFLAG IN ('M')
and
This works well: (ICHAR(SMRYFLAG)) = 77
and
This works well: SMRYFLAG = ('M')
I don't understand why simply stating SMRYFLAG = 'M' gives very poor
performance while all the other variations give almost instant response.
I'm looking for insight. I have rebuilt all the tables and indexes involved
and scanned the data looking for something unusual. Nothing turned up. I
even moved the location of the SMRYFLAG column in its table and tried
changing its data type. Still nuttin'.
What's up with this? This may provide useful insight into other possible
implications and applications.
Platform: Windows 2000 Pro
R:Base: Windows 6.5++ w/latest patch
Pentium III, 550 mHz, 256 MB RAM.
Thanks for any input.
Mike Ramsour
Voice: 740-829-4340
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