Dan, thanks for your reply.
When I changed the table definition to use the single index and
the multi-index I reloaded the data from scratch each time.
(I did the trials many times from scratch just to be sure and I
do get consistent results)
I also just did an optimize table as you suggest on the single
index just to be sure and I get the same results.
On Thu, Nov 21, 2002 at 05:22:05PM -0600, Dan Nelson wrote:
> In the last episode (Nov 21), johnt@stripped said:
> > Adding an irrelevant second column to an index instead of just a
> > single column index gives an incredible speedup and I don't know why!
> If you then remove the index, is it still fast? Maybe you are just
> seeing the results of mysql rebuilding the state key. When you modify
> an index, I believe mysql ends up rebuilding all indexes on that table.
> "optimize table mytable" would probably have given you the same speed
> Dan Nelson