pglogical 3 v3.7

The pglogical 3 extension provides logical streaming replication for PostgreSQL, using a publish/subscribe model. It is based on technology developed as part of the BDR3 project.

We use the following terms to describe data streams between nodes:

  • Nodes - PostgreSQL database instances
  • Providers and Subscribers - roles taken by Nodes
  • Replication Set - a collection of tables

These terms have been deliberately reused from the earlier Slony technology.

pglogical is new technology utilizing the latest in-core features, so we require both provider and subscriber nodes to run PostgreSQL 10 or newer.

Use cases supported are:

  • Upgrades between major versions (given the above restrictions)
  • Full database replication
  • Selective replication of sets of tables using replication sets
  • Selective replication of table rows at either provider or subscriber side (row_filter)
  • Selective replication of table columns at provider side
  • Data gather/merge from multiple upstream servers

Architectural details:

  • pglogical works on a per-database level, not whole server level like physical streaming replication
  • One Provider may feed multiple Subscribers without incurring additional disk write overhead
  • One Subscriber can merge changes from several origins and detect conflict between changes with automatic and configurable conflict resolution (some, but not all aspects required for multi-master).
  • Cascading replication is implemented in the form of changeset forwarding.