External Sources
A secondary database can be backed by an external source. Rather than accepting transactions from clients, it subscribes to an upstream feed and records what it reads as XTDB transactions.
The database is then a read-only mirror of that upstream — it rejects writes from the Postgres wire-compatible server and the Flight SQL server, and tracks the upstream as it changes.
Supported sources
Section titled “Supported sources”- Postgres
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Change-data-capture from a Postgres database — see Postgres External Source.
- Kafka Connect
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Records from a Kafka Connect topic — see Kafka Connect External Source.
Configuring an external source
Section titled “Configuring an external source”An external source is set up when you attach the secondary database: add an externalSource: entry to the ATTACH DATABASE config, alongside its log: and storage:.
See each source’s setup guide for the specifics.
Ingest-only nodes
Section titled “Ingest-only nodes”External sources can also run on a dedicated ingest-only node — a node with no query surface, useful for scaling ingestion independently of the nodes serving queries. See Ingest-only nodes.