replication slots
Working with PostgreSQL Replication Slots | Simplified Guide
47.2. Logical Decoding Concepts # 47.2.1. Logical Decoding 47.2.2. Replication Slots 47.2.3. Replication Slot Synchronization 47.2.4. Output Plugins 47.2.5.
Documentation: 9.4: pg_replication_slots
PostgreSQL also has streaming replication slots (see Section 26.2.5), but they are used somewhat differently there.
Using PostgreSQL Replication Slots
In Postgres 9.4, replication slots were introduced. A process receiving changes via streaming replication can create a replication slot on the primary server.