Performance Tuning: Create index for boolean column

Question

I have written a daemon processor which will fetch rows from one database and insert them into another for synchronizing. It will fetch rows based on a boolean

Answer 1

For a query like this a partial index would serve you best.

CREATE INDEX ON tbl (id) WHERE sync_done = FALSE;

However, for a use case like this, other synchronization methods may be preferable to begin with:

• Have a look at LISTEN / NOTIFY.
• Or use a trigger in combination with dblink.
• Or one of the many available replication methods.
  Streaming Replication was added with Postgres 9.0 and has become increasingly popular.