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Re: combined index ignored
Posted by: Rick James
Date: January 24, 2010 03:40PM

The index space for a table _may_ take more room than the table. In your case, you have 5 indexes, and the table itself is not very wide. So, I am not surprised that index_size > data_size. (Nothing to be alarmed about, but may indicate spurious indexes.)

Shrinking the field sizes -> Smaller -> more cacheable -> less I/O.
Better index -> less I/O and less CPU. -- INDEX(vehicle_id,date_time) is probably having to step over lots of unneeded rows, hence high CPU.
More RAM (and bigger cache setting) -> less I/O.

The InnoDB plugin is relatively new, but includes some significant performance tweaks. At this point, I cannot be more definitive.

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