SQL: Add C-based "vndbid" type and use it for image IDs

I had already rambled on the current composite type solution in
583ae868dfd3c882a8d2dd40b5d5ed099170c1c2 and I had already explored a
few alternatives. This was the one alternative I hadn't yet explored
because I wasn't sure the operational complexity was going to be worth
it, but after seeing how bad PostgreSQL was at optimizing queries with
composite types, I figured I might as well just go with this approach.

It improves performance of some queries by a *lot* (especially the image
selection query) and it's pretty elegant and convenient to work with.
Only downside is the complexity of compiling, installing and maintaining
a vndbid.so library for PostgreSQL.

1 files changed, 12 insertions, 1 deletions

diff --git a/README.md b/README.md
index 33be6269..18b1a948 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,8 @@ can stop the container and run:
 Global requirements:
 
 - Linux, or an OS that resembles Linux. Chances are VNDB won't run on Windows.
-- PostgreSQL 10 (older versions may work)
+- A standard C build system (make/gcc/etc)
+- PostgreSQL 10+ (including development files)
 - Perl 5.26+
 - Elm 0.19.1
 
@@ -88,11 +89,21 @@ util/multi.pl (application server, optional):
 ```
 
 - Setup a PostgreSQL server and make sure you can login with some admin user
+- Build the *vndbfuncs* PostgreSQL library:
+
+```
+  make -C sql/c
+```
+
+- Copy `sql/c/vndbfuncs.so` to the appropriate directory (either run
+  `sudo make -C sql/c install` or see `pg_config --pkglibdir` or
+  `SHOW dynamic_library_path`)
 - Initialize the VNDB database (assuming 'postgres' is a superuser):
 
 ```
   # Create the database & roles
   psql -U postgres -f sql/superuser_init.sql
+  psql -U postgres vndb -f sql/vndbid.sql
 
   # Set a password for each database role:
   echo "ALTER ROLE vndb       LOGIN PASSWORD 'pwd1'" | psql -U postgres