# crabka-connect-postgres
`crabka-connect-postgres` is a Postgres logical-decoding source connector for
`crabka-connect`.
The connector reads `pgoutput` changes from a logical replication slot and emits
Kafka Connect-style records with Protobuf-framed keys and values. DELETE events
emit a Protobuf-framed key with a `None` value, which represents a tombstone for
compacted topics.
## Offsets and acknowledgement
The connector tracks Postgres LSNs with `SourceOffset`. The offset partition
contains the database and replication slot, and the offset position contains the
LSN.
The live source reads with `pg_logical_slot_peek_binary_changes`, so polling does
not advance the replication slot. After the runtime writes the sink record,
commits the sink, and durably saves the checkpoint, it calls
`Source::acknowledge`. The connector then advances the Postgres slot to the
acknowledged LSN.
## Setup expectations
This slice expects:
- A `pgoutput` logical replication slot.
- A publication covering the configured tables.
- Configured table names for the source.
- No initial snapshot support. Only changes available through logical decoding
are emitted.
When table names are configured, the connector creates the publication if it is
missing and validates that the publication covers the configured tables. It also
creates the logical slot if it is missing.