SCHEMATA_REPLICAS view

Preview

This product or feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of the Service Specific Terms. Pre-GA products and features are available "as is" and might have limited support. For more information, see the launch stage descriptions.

The INFORMATION_SCHEMA.SCHEMATA_REPLICAS view contains information about schemata replicas.

Required role

To get the permissions that you need to query the INFORMATION_SCHEMA.SCHEMATA_REPLICAS view, ask your administrator to grant you the BigQuery Data Viewer (roles/bigquery.dataViewer) IAM role on the project. For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through custom roles or other predefined roles.

Schema

The INFORMATION_SCHEMA.SCHEMATA_REPLICAS view contains information about dataset replicas. The INFORMATION_SCHEMA.SCHEMATA_REPLICAS view has the following schema:

Column	Type	Description
catalog_name	STRING	The project ID of the project that contains the dataset.
schema_name	STRING	The dataset ID of the dataset.
replica_name	STRING	The name of the replica.
location	STRING	The region or multi-region the replica was created in.
replica_primary_assigned	BOOL	If the value is TRUE, the replica has the primary assignment.
replica_primary_assignment_complete	BOOL	If the value is TRUE, the primary assignment is complete. If the value is FALSE, the replica is not (yet) the primary replica, even if replica_primary_assigned equals TRUE.
creation_time	TIMESTAMP	The replica's creation time. When the replica is first created, it is not fully synced with the primary replica until creation_complete equals TRUE. The value of creation_time is set before creation_complete equals TRUE.
creation_complete	BOOL	If the value is TRUE, the initial full sync of the primary replica to the secondary replica is complete.
replication_time	TIMESTAMP	The value for replication_time indicates the staleness of the dataset. Some tables in the replica might be ahead of this timestamp. This value is only visible in the secondary region. If the dataset contains a table with streaming data, the value of replication_time will not be accurate.

Scope and syntax

Queries against this view must include a region qualifier. The following table explains the region scope for this view:

View name	Resource scope	Region scope
[PROJECT_ID.]`region-REGION`.INFORMATION_SCHEMA.SCHEMATA_REPLICAS[_BY_PROJECT]	Project level	REGION

Replace the following:

• Optional: PROJECT_ID: the ID of your Google Cloud project. If not specified, the default project is used.

• REGION: any dataset region name. For example, `region-us`.

Note: You must use a region qualifier to query INFORMATION_SCHEMA views. The location of the query execution must match the region of the INFORMATION_SCHEMA view.

Examples

This section lists example queries of the INFORMATION_SCHEMA.SCHEMATA_REPLICAS view.

Example: List all replicated datasets in a region

The following example lists all the replicated datasets in the US region:

SELECT * FROM `region-us`.INFORMATION_SCHEMA.SCHEMATA_REPLICAS;

The result is similar to the following:

+---------------------+-------------------+--------------+----------+--------------------------+-------------------------------------+---------------------+-------------------+------------------+
|    catalog_name     |    schema_name    | replica_name | location | replica_primary_assigned | replica_primary_assignment_complete |    creation_time    | creation_complete | replication_time |
+---------------------+-------------------+--------------+----------+--------------------------+-------------------------------------+---------------------+-------------------+------------------+
| myproject           | replica1          | us-east7     | us-east7 |                     true |                                true | 2023-04-17 20:42:45 |              true |             NULL |
| myproject           | replica1          | us-east4     | us-east4 |                    false |                               false | 2023-04-17 20:44:26 |              true |             NULL |
+---------------------+-------------------+--------------+----------+--------------------------+-------------------------------------+---------------------+-------------------+------------------+

Example: List replicated datasets and the primary replica for each

The following example lists all replicated datasets and their primary replica in the US region:

SELECT
 catalog_name,
 schema_name,
 replica_name AS primary_replica_name,
 location AS primary_replica_location,
 replica_primary_assignment_complete AS is_primary,
FROM
 `region-us`.INFORMATION_SCHEMA.SCHEMATA_REPLICAS
WHERE
 replica_primary_assignment_complete = TRUE
 AND replica_primary_assigned = TRUE;

The result is similar to the following:

+---------------------+-------------+----------------------+--------------------------+------------+
|    catalog_name     | schema_name | primary_replica_name | primary_replica_location | is_primary |
+---------------------+-------------+----------------------+--------------------------+------------+
| myproject           | my_schema1  | us-east4             | us-east4                 |       true |
| myproject           | my_schema2  | us                   | US                       |       true |
| myproject           | my_schema2  | us                   | US                       |       true |
+---------------------+-------------+----------------------+--------------------------+------------+

Example: List replicated datasets and their replica states

The following example lists all replicated datasets and their replica states:

SELECT
  catalog_name,
  schema_name,
  replica_name,
  CASE
    WHEN (replica_primary_assignment_complete = TRUE AND replica_primary_assigned = TRUE) THEN 'PRIMARY'
    WHEN (replica_primary_assignment_complete = FALSE
    AND replica_primary_assigned = FALSE) THEN 'SECONDARY'
  ELSE
  'PENDING'
END
  AS replica_state,
FROM
  `region-us`.INFORMATION_SCHEMA.SCHEMATA_REPLICAS;

The result is similar to the following:

+---------------------+-------------+--------------+---------------+
|    catalog_name     | schema_name | replica_name | replica_state |
+---------------------+-------------+--------------+---------------+
| myproject           | my_schema1  | us-east4     | PRIMARY       |
| myproject           | my_schema1  | my_replica   | SECONDARY     |
+---------------------+-------------+--------------+---------------+

Example: List when each replica was created and whether the initial backfill is complete

The following example lists all replicas and when that replica was created. When a secondary replica is created, its data is not fully synced with the primary replica until creation_complete equals TRUE.

SELECT
 catalog_name,
 schema_name,
 replica_name,
 creation_time AS creation_time,
FROM
 `region-us`.INFORMATION_SCHEMA.SCHEMATA_REPLICAS
WHERE
 creation_complete = TRUE;

The result is similar to the following:

+---------------------+-------------+--------------+---------------------+
|    catalog_name     | schema_name | replica_name |    creation_time    |
+---------------------+-------------+--------------+---------------------+
| myproject           | my_schema1  | us-east4     | 2023-06-15 00:09:11 |
| myproject           | my_schema2  | us           | 2023-06-15 00:19:27 |
| myproject           | my_schema2  | my_replica2  | 2023-06-15 00:19:50 |
| myproject           | my_schema1  | my_replica   | 2023-06-15 00:16:19 |
+---------------------+-------------+--------------+---------------------+

Example: Show the most recent synced time

The following example shows the most recent timestamp when the secondary replica caught up with the primary replica.

You must run this query in the region that contains the secondary replica. Some tables in the dataset might be ahead of the reported replication time.

SELECT
 catalog_name,
 schema_name,
 replica_name,
 -- Calculate the replication lag in seconds.
 TIMESTAMP_DIFF(CURRENT_TIMESTAMP(), replication_time, SECOND) AS replication_lag_seconds, -- RLS
 -- Calculate the replication lag in minutes.
 TIMESTAMP_DIFF(CURRENT_TIMESTAMP(), replication_time, MINUTE) AS replication_lag_minutes, -- RLM
 -- Show the last sync time for easier interpretation.
 replication_time AS secondary_replica_fully_synced_as_of_time,
FROM
 `region-us`.INFORMATION_SCHEMA.SCHEMATA_REPLICAS

The result is similar to the following:

+---------------------+-------------+--------------+-----+-----+-------------------------------------------+
|    catalog_name     | schema_name | replica_name | rls | rlm | secondary_replica_fully_synced_as_of_time |
+---------------------+-------------+--------------+-----+-----+-------------------------------------------+
| myproject           | my_schema1  | us-east4     |  23 |   0 |                       2023-06-15 00:18:49 |
| myproject           | my_schema2  | us           |  67 |   1 |                       2023-06-15 00:22:49 |
| myproject           | my_schema1  | my_replica   |  11 |   0 |                       2023-06-15 00:28:49 |
| myproject           | my_schema2  | my_replica2  | 125 |   2 |                       2023-06-15 00:29:20 |
+---------------------+-------------+--------------+-----+-----+-------------------------------------------+

A value of NULL indicates that the secondary replica was never fully synced to the primary replica.