[postgis-users] Postgis Lean

[Ralph Mason]

I am wondering if anyone has played with making a 'lean' version of 
postgis for 2d mapping where all the points are in the same projection.

It seems that it could radically decrease the amount of data required.  
If I look at a geometry for a two point line string, it looks like

SRID
offsetX
offsetY
scale
is3d
bvol.Z
linestring point 1 . Z
linestring point 2 . Z

This is a saving of 56 bytes for the single line string. Cutting down 
the linestring from 132 bytes to 76 bytes (43%), with no loss in 
functionality that I would use.  It would also shrink an index by some 
as well.

The savings in memory and disk access here for large datasets seems huge. 

It looks to me like doing a conditional compile to make this happen 
wouldn't be very difficult. Perhaps one for 2D only and another to 
remove SRID (so it's always considered as -1 it's just not stored). 

Can anyone spot any holes in the plan?

Thanks
Ralph