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

An index will certainly help but rather than polling which can impose load and concurrency issues if your database is heavily used it might be worth considering a notification method such as amqp or trigger/database queue based approach instead like Slony or Skytools Londiste. I have used both Slony and Londiste for trigger based replication and have found both excellent. My preference is for Londiste as it is much simpler to set up and manage (and if you have a simple use case stick to the older 2. branch).