Hi,
Yes, R-trees has been supported by mysql for quite some time,
but nevertheless they still require the first column of multi-column
index to be part of WHERE in order to activate such index.
Jacek
Bongki Moon wrote:
The problem Jacek was referrreing to comes from the fact that
the composite index is asymmetric - treating the first column as the major.
This limitation may be allevaited, to some extent if not all, by making
the composite index symmetric. Grid files and R-trees are examples of such
symmetric indexes. Unfortunately, however, I don't think they are supported
by mysql as yet.
Bongki
On Fri, 23 Jun 2006, Jacek Becla wrote:
The overhead related to adding 3rd element to the index is reasonable,
the only problem with such composite index is that you have to use a
constraint on the very first column of a composite index, so in practice
a query without spatial constraint will not be able to use such index.
BTW, the cleanest solution to providing truly good support for both
spatial and temporal queries is to duplicate data and optimize (cluster)
each copy differently (and I know Jim Gray agrees with that 100%).
The only problem is the cost (however this might turn out to be
the cheapest solution anyway...)
Jacek
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