Re: mysql query with modulus in where clause
Posted by:
Rick James
Date: January 12, 2013 11:13AM
> WHERE (2567 -lastModifiedCalendarId) % 7 =0
There is no advantage in trying to optimize "% 7" (assuming the values are somewhat evenly distributed. The optimizer is likely to decide that a table scan is better than bouncing between an index and the data.
> and 2567 - lastUsedCalendarId < 7
On the other hand, _this_ might be optimizable:
AND lastUsedCalendarId > 2567 - 7
would let the optimizer consider using
> index idx_lastUsedCalendarId(lastUsedCalendarId)
The optimizer will not (or at least very rarely) use more than one INDEX in a single SELECT. So, based on what I see so far, this is useless:
> index idx_lastModifiedCalendarId(lastModifiedCalendarId),
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January 11, 2013 03:02PM
Re: mysql query with modulus in where clause
1997
January 12, 2013 11:13AM
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