AngaraStream

AngaraStream provides Change Data Capture (CDC) for AngaraBase via subscriptions over a table’s change log.

API

-- create a subscription on a table's DML events
CREATE SUBSCRIPTION "my-sub" ON TABLE public.orders
  FOR EVENTS (INSERT, UPDATE, DELETE)
  WITH (start_offset = 'latest');

-- poll up to N events (does NOT advance the cursor)
SELECT * FROM angara_stream_poll('my-sub', batch_size => 100);

-- acknowledge up to an offset (advances the cursor)
SELECT angara_stream_ack('my-sub', offset => 42);

-- remove the subscription
DROP SUBSCRIPTION "my-sub";

FOR EVENTS (...) may list any subset of INSERT/UPDATE/DELETE; an empty list defaults to all three.

start_offset semantics

The start_offset WITH-option controls which events a new subscription sees.

The change-log buffer is bounded: events older than the retained window have already been evicted and are not delivered even with 'earliest' — the cursor starts at the oldest event still in the buffer. For a full re-seed you must drop and recreate the subscription (and reload the table out of band):

DROP SUBSCRIPTION "my-sub";
CREATE SUBSCRIPTION "my-sub" ON TABLE public.orders
  FOR EVENTS (INSERT, UPDATE, DELETE)
  WITH (start_offset = 'earliest');

SQLSTATE