Well, first off, a btree index is fairly useless for this query,
because btree has no concept that the hstore has any sub-structure.
A GIN index or GIST index could work though. Secondly, you have to
remember that indexable WHERE conditions in Postgres are *always* of
the form "WHERE indexed_column indexable_operator some_comparison_value".
And the student was enlightened....
Cheers, seeing sensible explain plans now.
You might care to read
http://www.postgresql.org/docs/9.4/static/indexes.html
to get a better handle on what Postgres indexes can and can't do.
Will do, thanks again.
Mike.
