Cleaning up indexes

My database was converted from MySQL a while back and has maintained all
of the indexes which were previously used. Tt the time however, there
were limitations on the way PostgreSQL handled the indexes compared to
MySQL.

Meaning that under MySQL, it would make use of a multi-column index even
if the rows within did not match. When the conversion was made more
indexes were created overall to correct this and proceed with the
conversion.

Now the time has come to clean up the used indexes. Essentially, I
want to know if there is a way in which to determine which indexes are
being used and which are not. This will allow me to drop off the
unneeded ones and reduce database load as a result.

And have things changed as to allow for mismatched multi-column indexes
in version 7.4.x or even the upcoming 8.0.x?

Martin Foster
martin(at)ethereal-realms(dot)org