[pgpointcloud] uncompressed pointcloud size

[Sandro Santilli]

Hello all,
I've been playing with pgcloud today and was surprised by the size
of uncompressed patches enough to write an email here.

I've inspected size using the PostgreSQL pg_column_size function.

The patch contains 65,535 points of 8 dimensions (of 8 bytes) each.
With the "dimensional" compression, size is 40,441 bytes.
Uncompressed, size is 4,194,487 bytes

The closest equivalent PostGIS multipoint (with half the dimensions)
is is 68,595 bytes. Makes me think that if you could store double as
many points in a MULTIPOINT you'd get double that size, which is
137,190 bytes (in reality you'd get a little less as SRID would not
be repeated). In any case that's far away from the 4M reported for
the uncompressed patch.

Could there be a bug in the code, fluffing the value far higher than
really needed to store all values ? Or how can an uncompressed pcpatch
be much bigger an a multipoint geometry (also uncompressed) ?

--strk; 

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