On 12/26/05, Pavel Stehule <[EMAIL PROTECTED]> wrote: > (1,1) <* (1,2) = true > (1,2) <* (2,1) is NULL > (2,3) <* (1,2) = false > > it's usefull for multicriterial optimalisation
This is indeed a sane and useful function which should be adopted by the SQL standard.. in postgresql this would easily enough be implemented as a user function so I'm not sure we need special support for it. The idea is that in a multidimension comparison you can only sometimes say when one tuple is strictly less than (or greater than) another because differing dimensions are incomparable. So, like his example, we can not say if (1,2) is lesser or greater than (2,1) because saying so would require some priority of the dimensions which may not be known or may not exist, it is only clear that they are not equal.. ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
