Hi All,
  I updated a large mysql database so that the tables took up less space, I set the right field types (they were all varchar rather than a mixture of int's, reals, etc) I also fixed all the dates which were in the format MM:DD:YYYY to 'YYYYMMDD' so that numerical comparisons could be used. I flushed and optimized the tables. The old database calls the script produced looked like:-
SELECT sum(numlog) FROM table1 WHERE date IN ( '12:04:2007', '12:05:20
+07', ... up to 500 odd dates)

[download]
They now look like:-
SELECT sum(numlog) FROM table1 WHERE date >= 20071204 AND date < 20080
+112

[download]
I fired it up, looking forward to what I expected to be a huge speed increase (the table I'm testing has over half a million records). Right now I want to cry as the new code it actually running slower. So I tested just the MySQL and it gave me the same results, trying out the new sql and a new take on the old:-
SELECT sum(numlog) FROM table1 WHERE date IN ( '20071204', '20071205',
+ ... 30 days)

[download]
The new one take about 4.2 seconds on average, the old one takes about 3.9 on average.
What gives???? How can all those OR's possibly be faster than a > and a <?


Lyle

In reply to Perl and MySQL woes by cosmicperl

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