Citus Blog

Materialized views were a long awaited feature within Postgres for a number of years. They finally arrived in Postgres 9.3, though at the time were limited. In Postgres 9.3 when you refreshed materialized views it would hold a lock on the table while they were being refreshed. If your workload was extremely business hours based this could work, but if you were powering something to end-users this was a deal breaker. In Postgres 9.4 we saw Postgres achieve the ability to refresh materialized views concurrently. With this we now have fully baked materialized view support, but even still we've seen they may not always be the right approach.