Are you able to cluster the table ? The idea is that rows ordered in the same way as the index might reduce it's size ?
I'm not sure on this. There are other indexes on these table partitions as well.
Another bit of useful info that I should have shared immediately is that this is a monthly partitioned table, going back years. We don't drop old partitions (yet) on this one. For now we've only added this index to a few individual partitions. The hope was to add it to all of them and then eventually the template (using an older version of pg_partman).
Don.
