Zsort ?

[Attila Csipa]

Maybe this would require a RFC, but I do not see this issue addressed in 
existing .map references or RFC, I wanted to hear your opinion on this (there 
was a short discussion about this, but a lot has changed in Mapserver since 
then).

What would you say if we introduced a drawing sort order inside layers ? As it 
is now, all the features are drawn by their order in the data storage. If 
using SQL queries one can define a sort order, but for shapefiles or other 
local file storages this is not an option. This would mean introducing a sort 
of ORDERITEM keyword (or an 'order' binding if we are thinking along the 
lines of RFC19) which, if present, would be used to build a sorting table, 
and then provide a seek function which would help the nextItem approach for 
these data storages.

The advantages of this should be obvious - for example if you have an area 
column in your dbf you could draw large polygons first so you would not 
obstruct small ones, or if you need to sort on a timestamp, etc.