Implementation details

Postgres replication protol use-cases

The postgres replication protocol provides the necessary information to propagate the update. This table summarizes the various cases used to build a WHERE clause.

Operation	Indicator	Values	OldValues	Where	Notes
UPDATE	K	Modified values	Old primary Key	PK=OldValues.PK	Primary key was modified
UPDATE	O	Modified values	Full row	columns=OldValues	Replica identity full
UPDATE	00	Modified values including PK		PK=Values.PK	Primary Key was not modified
DELETE	K	Primary key		PK=Values.PK	Primary key was deleted
DELETE	O	Full row		columns=Values	Replica Identity Full
DELETE	00	Should never happen

References

• Articles
  • Fastware
  • Dolthub
• Postgres Documentation
  • Logical replication
  • Logical decoding
• Protocol:
  • Streaming Replication
  • Logical Replication
• Go pgx and tools
  • jackc/pgx
  • jack/pglogrepl