[Monetdb-developers] monetdb cost model

Stefan Manegold Stefan.Manegold at cwi.nl
Mon Mar 8 19:09:51 CET 2010


On Mon, Mar 08, 2010 at 08:02:35PM +0530, anshul gangwar wrote:
> hello ,
>  
>      Is the cost model used at compile time or at runtime for estimation of cardinalities

I don't know which is "*the* cost model" that you refer to, but as we tried
to explain before the current open source version of MonetDB/XQuery does not
do any cardinality estimation for XQuery optimization, neither at compile
time nor at runtime.

The various operations in the MonetDB kernel do some "ad hoc" cardinality
estimation based on the properties of their inputs or on sampling.
See the code in MonetDB/src/gdk/ for details.

Stefan

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