How to use extensions in Postgres installed with Homebrew on Mac OSX - postgresql

Question

I'd like to use the SPI extension in Postgres 10.2, which I installed with Homebrew. However,
CREATE EXTENSION spi;
fails with
ERROR: could not open extension control file "/usr/local/share/postgresql/extension/spi.control": No such file or directory
Looking inside that extension directory, I see many extensions, but not SPI. The Postgres documentation mentions that extensions would reside in a contrib directory of the distribution and that you can then build them individually, but I can't seem to find this directory anywhere. Any idea how I can obtain and install the SPI module?

Answer 1

https://www.postgresql.org/docs/current/static/contrib-spi.html
Each of the groups of functions described below is provided as a
separately-installable extension.
so you check and try:
t=# select * from pg_available_extensions where name in ('refint','timetravel','autoinc','insert_username','moddatetime');
name | default_version | installed_version | comment
-----------------+-----------------+-------------------+-------------------------------------------------------------
moddatetime | 1.0 | | functions for tracking last modification time
autoinc | 1.0 | | functions for autoincrementing fields
insert_username | 1.0 | | functions for tracking who changed a table
timetravel | 1.0 | | functions for implementing time travel
refint | 1.0 | | functions for implementing referential integrity (obsolete)
(5 rows)
t=# create extension refint ;
CREATE EXTENSION
t=# create extension timetravel;
CREATE EXTENSION
and so on...