Index overhead cost reporting

Hi,

I was wondering whether anyone has any insight with regards to
measuring and reporting the overhead of maintaining indexes on
relations. If an UPDATE is issued to a table with, say, 6 indexes, it
would be useful to determine how much time is spent updating each of
those indexes. And perhaps such timings would not be confined to
indexes, but also other dependants that add overhead, such as
triggers, rules, and in future, eager incremental materialised view
updates.

One use case I had in mind is observing whether any index is
particularly burdensome to the overall plan. Then an analysis of
those numbers could show that, for example, 25% of the time spent on
DML on table my_table were spent on maintaining index
idx_my_table_a... and index that's not often used.

Is that something that could be provided in an EXPLAIN ANALYSE node?

Thom