[SQL] Indices and time spans

[Itai Zukerman]

I have this:

      SELECT ...
      FROM trade, entry
      WHERE AGE( CURRENT_TIMESTAMP, posted ) <= '5 minutes'::TIMESPAN
        AND trade.entryId = entry.entryId

That is, fetch all trades executed in the last 5 minutes.

This query seems to run pretty slowly when trade is filled.  Putting
an index on trade ( posted ) doesn't seem to help any (the same query
plan is generated).  Any suggestions?

-itai