postgres indexes

I'm progressively more convinced PostgreSQL is my next "emacs", as in "a tool I'm addicted to and I'm determined to find out everything about it".

I'm starting with some of the internals, and some deep descriptions about its various types of indexes.  Those pages provided me a bunch of hours of reading and knowledge on postgres internals.

http://www.louisemeta.com/blog/indexes-gin/
https://habr.com/en/company/postgrespro/blog/441962/
http://www.interdb.jp/pg/

Also, this week I read somewhere that postgres was first written in Lisp! I guess it shows when you run EXPLAIN on a query. I just confirmed it for a fact. :)