I'll second what Chris said, which is that all the joined columns should be of the same type for speed.
Also, your substring and LIKE comparisons are going to be problematic, as those are string operations, not numeric, and MySQL is having to convert all the decimal values to strings before comparing them. It works but as you've found can be very slow, since you a) have to convert every row, and b) have to do an unindexed comparison. Dan On 10/27/06, Chris <[EMAIL PROTECTED]> wrote:
[EMAIL PROTECTED] wrote: >> From: Jerry Schwartz [mailto:[EMAIL PROTECTED] >> >> What is going slower, INSERT / UPDATES or SELECTS? > > Complex SELECTs > >> CHAR should make for quite efficient processing, since to a >> large degree nobody cares what's in there: it just slams the >> data in, or does a simple byte-by-byte comparison. There is >> probably hardware support for that kind of operation. Decimal >> arithmetic, on the other hand, requires more data >> manipulations. The size of the column probably is outweighed >> by the more complex data handling. > > I am doing the following operations: > > - Joins based on indexed columns Did you change *all* columns involved in the joins? Otherwise you have: decimal joining to char which mysql will need to convert internally to be the same type.. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
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