pglogical 2Edit this page
The pglogical 2 extension provides logical streaming replication for PostgreSQL, using a publish/subscribe model. It is based on technology developed as part of EDB Postgres Distributed.
pglogical 2 is open source
EDB maintains pglogical as a service to the PostgreSQL community. For license and copyright information, or for access to the source, visit the project page at https://github.com/2ndQuadrant/pglogical
We use the following terms to describe data streams between nodes, deliberately reused from the earlier Slony technology:
- Nodes - PostgreSQL database instances
- Providers and Subscribers - roles taken by Nodes
- Replication Set - a collection of tables
pglogical is utilising the latest in-core features, so we have these version restrictions:
- Provider & subscriber nodes must run PostgreSQL 9.4+
- PostgreSQL 9.5+ is required for replication origin filtering and conflict detection
- Additionally, subscriber can be Postgres-XL 9.5+
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 publisher or subscriber side (row_filter)
- Selective replication of table columns at publisher side
- Data gather/merge from multiple upstream servers
- 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.