PostgreSQL-9.3.4 was so slow.
I had been using PostgreSQL-9.3.4 and enabled streaming replication. My web application queries against a primary database, but queries were so slow. Since I couldn't find any hardware issue and disk I/O issue. Everything looked good.How to fix the performance issue
I looked at PostgreSQL release notes (9.3.4 through 9.3.19). I couldn't find any query issues, but I decided to upgrade primary and secondary databases at the same time. After I upgraded, query performance is much better than ever. I strongly recommend to upgrade 9.3.x to 9.3.19 as soon as possible if you are still using a lower version. This is just a minor version up, so you can keep database cluster.
