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 > > _______________________________________________ LSST-data mailing list [email protected] http://www.lsstmail.org/mailman/listinfo/lsst-data
