"James DeMichele" <James.DeMichele@redfin.com> wrote ..
> Then, I have the following index on the table:
> "this_index" (status, source_id, <another_column>)
If you have many queries of this type, do
CLUSTER this_index ON tablename;
and retry the SELECT.
MySQL is using some sort of auto-clustering ISAM on the other box mayhaps?
In Postgres you will have to re-CLUSTER periodically if there are INSERTs and UPDATEs.