[postgis-devel] gserialized-v2

Sandro Santilli strk at kbt.io
Sat Jun 22 01:05:12 PDT 2019

On Fri, Jun 21, 2019 at 03:01:54PM -0700, Paul Ramsey wrote:

> - gserialized_from_lwgeom() (and the two functions riding on top of
> it, geometry_serialize() and geography_serialize(), which are
> preferred when calling from inside ./postgis) will write out v2
> geometries, so databases will slowly get re-written with the new form
> over time

What I'd like to be able to do:

  1. See the info about serialization version and full flagset from ST_Summary
  2. Compare ST_MemSize(force_v1(v1)) and ST_MemSize(force_v2(v2))
     (this would need exposing V1 encoding to the SQL level)
  3. Use `UPDATE mytable SET geom = ST_Noop(geom)` to force all things to v2

> - The extra flag space on gflags that has been freed up by moving the
> IsSolid flag into the xflags area could be used of an IsPoint flag, to
> allow a lightweight point type. A lightweight x/y point could then be
> 24 bytes (varsize + srid/flags + x + y) instead of 32 bytes (varsize +
> srid/flags + type + padding + x + y), for a 25% savings for simple
> points.

This is a good one!

Where's the serialized version info, btw ?
Would you show some C structs in this thread ? :)

Note my `make check` fails  pretty early with:

  ../loader/Point ........ failed (dumper geog test: dumping loaded table: /tmp/pgis_reg/dumper.err)
  Done (postgis major version: 3).
  Output shape: Point
  Dumping: XUnknown WKB type (0) for record 0


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