There are actually a few strong solutions out there for Mysql, most starting with change data capture like: https://github.com/shyiko/mysql-binlog-connector-java (I link that one in particular because he links to alternatives right in his readme!)

Pgsql is a bit harder, but if I needed to start somewhere it would be with:

https://github.com/debezium/debezium

or https://github.com/confluentinc/bottledwater-pg

These are the start of pretty sophisticated solutions where you need super real-time elasticsearch indexes and can bring up infra like Kafka.

For many applications, queueing an update when something hits your ORM to update, with the hourly/daily refresh is pretty satisfactory.