Keeping snapshots of shared buffers and prewarming accordingly.
One major problem that i face during a failover is that contents of shared buffers on the slave are invalid or irrelevant. pg_prewarm that came with 9.4 is a good solution but usually you would use it by prewarming a table, or you could manually get the pages from pg_buffercache and prewarm the pages you had on the master prior to the failover, not everyone can do this especially during a failover, i reckon only a few can, so i wrote an extension called ' pgcozy ' (comments about the name should be directed to @ DenishPatel hehe). This extension basically utilizes 2 well known extensions, pg_buffercache and pg_prewarm. pg_buffercache has helped me so many times in the past that i couldn't even count, it shows the contents (pages) of the shared buffers and their popularity. pg_prewarm is a new (9.4) extension that can be used on the block or relation level. In our case we will use it in the block level and we will put these 2 extensions to work. pgcozy, stores on demand...