Add pg_stat_statements extemsion for Postgres Query Optimization

[olivierobert]

Why

While Postgres is used in all client projects we do, not much attention is put on performance beyond n+1 queries (via the gem bullet). Besides, if a project does not use New Relic or another similar third-party service, we usually have no insights into how the database queries are performing.

Postgres comes with its own extension to log and analyze all queries: https://www.postgresql.org/docs/current/pgstatstatements.html. This is a good overview article: http://blog.crunchydata.com/blog/tentative-smarter-query-optimization-in-postgres-starts-with-pg_stat_statements.

It does not have any performance hits on the actual database. It's an easy win for observability.

Who Benefits?

• Developers who struggle with database performance issues.
• Clients who can have faster apps.

Next Steps

• Add pg_stat_statements by default in the Rails template

• Document the usage on Compass code conventions for Rails