Hey everyone ! Bumping an older thread <https://www.postgresql.org/message-id/flat/CA%2BKBOKwJkG5_vMi3W6D9mXMbLJA_i4qrpPfa-Kg5EqLvBBMYow%40mail.gmail.com>, I've read the GIN readme in the code base and have skimmed through the implementation, it made me wonder - would it be possible to use the index to query for distinct / count distinct values, at least for some key types ?
For instance, say I have a GIN index on a single, highly cardinal but non-unique text column (a-la 'name'); from my very limited understanding, would it be possible to query for distinct / count distinct values via roughly: - Traversing the GIN entry tree tuples - Gathering the key data from said tuples - Discarding keys with no / empty posting lists, as they aren't discarded from the tree - Traversing the pending list for indices with fastupdate & merging the result set I'm probably off by quite a lot, but I'd really appreciate your great insight on the above. Thanks ! Danny
