== Google Summer of Code 2021 ==

**Augment PostGIS 3.2 with GIST support added to PG14**

''Expected outcome'': Speed up GiST index building in PostGIS

''Skills required'': C or willing to learn, ability to compile PostgreSQL code, ability to compile PostGIS code, some familiarity with PostGIS / PostgreSQL is preferable

''Mentors'': Giuseppe Broccolo, Regina Obe

''Difficulty'': Medium

``Student Test'':

1. git clone PostGIS code from one of PostGIS repos -
2. git clone code from PostgreSQL git repo (master branch) - 
3. Compile both and install PostGIS 3.2 (master branch) extension into PostgreSQL 14 dev database
4. Setup a public fork of PostGIS repo for your work and do the development work
5. Once ready submit a pull request to any of PostGIS repos 


''Additional detail'':

Recently this patch <https://commitfest.postgresql.org/29/2276/> which adds
more infrastructure to the GiST has been included in PG14. It should speed
up the build of a GiST index after some (fast) pre-sorting of the data
which needs to be indexed. Some tests for the PG's internal type point
(that uses Zsort as fast pre-sorting of the data) showed that the build is
up to 5 times faster.

I'd like to study a possible implementation for PostGIS data types.
Basically, it would require to add this support function
<https://github.com/glukhovn/postgres/blob/225a49161fae9388651373d4beb8dcba99059339/src/include/access/gist.h#L37>
and this other one
<https://github.com/glukhovn/postgres/blob/225a49161fae9388651373d4beb8dcba99059339/src/include/access/gist.h#L38>
in the operator classes which use the GiST infrastructure (e.g. this one
<https://github.com/postgis/postgis/blob/8b13c3e2f8366d902dbf516ec17de09ae84361f4/postgis/postgis.sql.in#L781>
).