New in v21.2: Changefeeds are supported on regional by row tables. When working with changefeeds on regional by row tables, it is necessary to consider the following:
- Setting a table's locality to
REGIONAL BY ROWis equivalent to a schema change as thecrdb_regioncolumn becomes a hidden column for each of the rows in the table and is part of the primary key. Therefore, when existing tables targeted by changefeeds are made regional by row, it will trigger a backfill of the table through the changefeed. (See Schema changes with a column backfill for more details on the effects of schema changes on changefeeds.)
If the schema_change_policy changefeed option is configured to stop, the backfill will cause the changefeed to fail.
Setting a table to
REGIONAL BY ROWwill have an impact on the changefeed's output as a result of the schema change. The backfill and future updated or inserted rows will emit output that includes the newly addedcrdb_regioncolumn as part of the schema. Therefore, it is necessary to ensure that programs consuming the changefeed can manage the new format of the primary keys.Changing a row's region will appear as an insert and delete in the emitted changefeed output. For example, in the following output in which the region has been updated to
us-east1, the insert messages are emitted followed by the delete messages:
. . .
{"after": {"city": "washington dc", "crdb_region": "us-east1", "creation_time": "2019-01-02T03:04:05", "current_location": "52372 Katherine Plains", "ext": {"color": "black"}, "id": "54a69217-35ee-4000-8000-0000000001f0", "owner_id": "3dcc63f1-4120-4c00-8000-0000000004b7", "status": "in_use", "type": "scooter"}, "updated": "1632241564629087669.0000000000"}
{"after": {"city": "washington dc", "crdb_region": "us-east1", "creation_time": "2019-01-02T03:04:05", "current_location": "75024 Patrick Bridge", "ext": {"color": "black"}, "id": "54d242e6-bdc8-4400-8000-0000000001f1", "owner_id": "3ab9f559-b3d0-4c00-8000-00000000047b", "status": "in_use", "type": "scooter"}, "updated": "1632241564629087669.0000000000"}
{"after": {"city": "washington dc", "crdb_region": "us-east1", "creation_time": "2019-01-02T03:04:05", "current_location": "45597 Jackson Inlet", "ext": {"brand": "Schwinn", "color": "red"}, "id": "54fdf3b6-45a1-4c00-8000-0000000001f2", "owner_id": "4339c0eb-edfa-4400-8000-000000000521", "status": "in_use", "type": "bike"}, "updated": "1632241564629087669.0000000000"}
{"after": {"city": "washington dc", "crdb_region": "us-east1", "creation_time": "2019-01-02T03:04:05", "current_location": "18336 Katherine Port", "ext": {"color": "yellow"}, "id": "5529a485-cd7b-4000-8000-0000000001f3", "owner_id": "452bd3c3-6113-4000-8000-000000000547", "status": "in_use", "type": "scooter"}, "updated": "1632241564629087669.0000000000"}
{"after": null, "updated": "1632241564629087669.0000000000"}
{"after": null, "updated": "1632241564629087669.0000000000"}
{"after": null, "updated": "1632241564629087669.0000000000"}
{"after": null, "updated": "1632241564629087669.0000000000"}
. . .
See the changefeed responses section for more general information on the messages emitted from a changefeed.
See also
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