Statistics and Index Usage Data

Hello all:

I’m curious if there are any ways to query custom/extended multivariate statistics usage? I tried a few web searches, but can’t find anything there or in the docs. I imagine this simply isn’t implemented (is it expensive to keep this data?), but just wanted to double check.

Also, is there any way to query index usage based on type of index (brin, gist, btree, etc.)? I couldn’t see anything obvious to do so here: https://wiki.postgresql.org/wiki/Index_Maintenance#Summarize_keyspace_of_a_B-Tree_index

[FYI: Many of the links at the bottom of the above page (related to index pruning) fail on current versions of postgreSQL.]

Best I could come up with so far was a text search for the USING clause in indexdef of pg_indexes.

Thanks,

Casey Meijer