Cleanup build

[cvvergara]

Before working on the src code,
the build needs to be cleaned up and adjusted so it can find postgres in other environments besides unix.

[cvvergara]

The postgres version number was not been captured correctly

POSTGRESQL_VERSION_NUMBER=120700
-- POSTGRESQL_VERSION_STRING=PostgreSQL 12.7 (Ubuntu 12.7-0ubuntu0.20.04.1)
-- Found POSTGRESQL: /usr/include/postgresql/12/server (found version "12.7") 
Found compatible PostgreSQL 12.7 (Ubuntu 12.7-0ubuntu0.20.04.1)
-- PG_FULL_VERSION=120000

[cvvergara]

MobilityDb is not using protobuf in its code and it is not building postgis so there is no need to checj for protobuf

[cvvergara]

Understanding with Postgis 3
The error is different, (note that on first error when creating the extension it stops, there might me more)

ERROR:  could not load library "/usr/lib/postgresql/11/lib/libMobilityDB.so": /usr/lib/postgresql/11/lib/libMobilityDB.so: undefined symbol: getSRSbySRID

But interesting:

git grep getSRSbySRID ..
../point/include/postgis.h:extern char *getSRSbySRID(FunctionCallInfo fcinfo, int32_t srid, bool short_crs);
../point/src/tpoint_out.c:      srs = getSRSbySRID(fcinfo, srid, true);
../point/src/tpoint_out.c:      srs = getSRSbySRID(fcinfo, srid, false);

On Postgres 3 that one is defined in:
https://github.com/postgis/postgis/blob/stable-3.1/libpgcommon/lwgeom_cache.c
on Postgres 2.5 is defined in
https://github.com/postgis/postgis/blob/stable-2.5/postgis/lwgeom_export.c

In any case It is not the topic of this PR, yet. but those comments are a reminder of what to look when trying to make it work with PostGIS 3

[cvvergara]

Need to find PostGIS to make sure that postgis-2.5 is found and that it is used

[cvvergara]

@estebanzimanyi
There is no need to review while it is work in progress, I haven't clicked the button of "Ready for review", it still a draft

[cvvergara]

@estebanzimanyi
From what I understand in this code:
https://github.com/MobilityDB/MobilityDB/blob/develop/CMakeLists.txt#L149-L169
When lwgeom is not found, then there is a fatal error and nothing is done.
So its always building "with postgis", never without it.

[cvvergara]

There is a FindGSL but its avaliable on cmake 3.2 will see what happens when using that one
https://cmake.org/cmake/help/latest/module/FindGSL.html

[estebanzimanyi]

@estebanzimanyi <https://github.com/estebanzimanyi> From what I understand in this code: https://github.com/MobilityDB/MobilityDB/blob/develop/CMakeLists.txt#L149-L169 When lwgeom is not found, then there is a fatal error and nothing is done. So its always building "with postgis", never without it.

Indeed MobilityDB is always built with postgis. BTW these lines come from Regina https://github.com/MobilityDB/MobilityDB/pull/19/files

[cvvergara]

About the lines, that is using the FindPostgresql, I created a custom one
https://github.com/cvvergara/MobilityDB/blob/cleanup-build/cmake/FindPOSTGRESQL.cmake
So now everything is based on the custom one, that gets everything that its needed in mobitlityDB
To avoid confision its FindPOSTGRESQL instead of FindPostgresql

[cvvergara]

Basically the description of the changes of this PR are on the titles of the different commits.

[cvvergara]

@estebanzimanyi Now you can review :-)