List:General Discussion« Previous MessageNext Message »
From:johnt Date:November 21 2002 11:13pm
Subject:Re: irrelevant multi-column index yields incredible speedup!
View as plain text  
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.

John


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
> boost.
> 
> -- 
> 	Dan Nelson
> 	dnelson@stripped
Thread
irrelevant multi-column index yields incredible speedup!johnt21 Nov
  • Re: irrelevant multi-column index yields incredible speedup!Dan Nelson22 Nov
    • Re: irrelevant multi-column index yields incredible speedup!johnt22 Nov