citus/src/backend/distributed/sql/udfs/citus_drop_trigger/12.2-1.sql

69 lines
3.3 KiB
PL/PgSQL

CREATE OR REPLACE FUNCTION pg_catalog.citus_drop_trigger()
RETURNS event_trigger
LANGUAGE plpgsql
SET search_path = pg_catalog
AS $cdbdt$
DECLARE
constraint_event_count INTEGER;
v_obj record;
dropped_table_is_a_partition boolean := false;
BEGIN
FOR v_obj IN SELECT * FROM pg_event_trigger_dropped_objects()
WHERE object_type IN ('table', 'foreign table')
LOOP
-- first drop the table and metadata on the workers
-- then drop all the shards on the workers
-- finally remove the pg_dist_partition entry on the coordinator
PERFORM master_remove_distributed_table_metadata_from_workers(v_obj.objid, v_obj.schema_name, v_obj.object_name);
-- If both original and normal values are false, the dropped table was a partition
-- that was dropped as a result of its parent being dropped
-- NOTE: the other way around is not true:
-- the table being a partition doesn't imply both original and normal values are false
SELECT (v_obj.original = false AND v_obj.normal = false) INTO dropped_table_is_a_partition;
-- The partition's shards will be dropped when dropping the parent's shards, so we can skip:
-- i.e. we call citus_drop_all_shards with drop_shards_metadata_only parameter set to true
IF dropped_table_is_a_partition
THEN
PERFORM citus_drop_all_shards(v_obj.objid, v_obj.schema_name, v_obj.object_name, drop_shards_metadata_only := true);
ELSE
PERFORM citus_drop_all_shards(v_obj.objid, v_obj.schema_name, v_obj.object_name, drop_shards_metadata_only := false);
END IF;
PERFORM master_remove_partition_metadata(v_obj.objid, v_obj.schema_name, v_obj.object_name);
END LOOP;
FOR v_obj IN SELECT * FROM pg_event_trigger_dropped_objects()
LOOP
-- Remove entries from pg_catalog.pg_dist_schema for all dropped tenant schemas.
-- Also delete the corresponding colocation group from pg_catalog.pg_dist_colocation.
--
-- Although normally we automatically delete the colocation groups when they become empty,
-- we don't do so for the colocation groups that are created for tenant schemas. For this
-- reason, here we need to delete the colocation group when the tenant schema is dropped.
IF v_obj.object_type = 'schema' AND EXISTS (SELECT 1 FROM pg_catalog.pg_dist_schema WHERE schemaid = v_obj.objid)
THEN
PERFORM citus_internal.unregister_tenant_schema_globally(v_obj.objid, v_obj.object_name);
END IF;
-- remove entries from citus.pg_dist_object for all dropped root (objsubid = 0) objects
PERFORM master_unmark_object_distributed(v_obj.classid, v_obj.objid, v_obj.objsubid);
END LOOP;
SELECT COUNT(*) INTO constraint_event_count
FROM pg_event_trigger_dropped_objects()
WHERE object_type IN ('table constraint');
IF constraint_event_count > 0
THEN
-- Tell utility hook that a table constraint is dropped so we might
-- need to undistribute some of the citus local tables that are not
-- connected to any reference tables.
PERFORM notify_constraint_dropped();
END IF;
END;
$cdbdt$;
COMMENT ON FUNCTION pg_catalog.citus_drop_trigger()
IS 'perform checks and actions at the end of DROP actions';