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The SHOW RANGE ... FOR ROW statement shows information about a range for a single row in a table or index. This information is useful for verifying how SQL data maps to underlying ranges, and where the replicas for a range are located.
Note:
This feature is experimental.This feature is subject to change. To share feedback and/or issues, contact Support.
Note:
To show information about the ranges for all data in a table, index, or database, use the SHOW RANGES statement.
Syntax
SHOW RANGE FROM TABLE <tablename> FOR ROW (value1, value2, ...)
SHOW RANGE FROM INDEX [ <tablename> @ ] <indexname> FOR ROW (value1, value2, ...)
Required privileges
The user must have the SELECT privilege on the target table.
Parameters
| Parameter | Description |
|---|---|
tablename |
The name of the table that contains the row that you want range information about. |
indexname |
The name of the index that contains the row that you want range information about. |
(value1, value2, ...) |
The values of the indexed columns of the row that you want range information about, as a tuple. In previous releases, this statement required the values of all columns of a row. |
Response
The following fields are returned:
| Field | Description |
|---|---|
start_key |
The start key for the range. |
end_key |
The end key for the range. |
range_id |
The range ID. |
lease_holder |
The node that contains the range's leaseholder. |
lease_holder_locality |
The locality of the leaseholder. |
replicas |
The nodes that contain the range replicas. |
replica_localities |
The locality of the range. |
Examples
Setup
The following examples use MovR, a fictional vehicle-sharing application, to demonstrate CockroachDB SQL statements. For more information about the MovR example application and dataset, see MovR: A Global Vehicle-sharing App.
To follow along, run cockroach demo to start a temporary, in-memory cluster with the movr dataset preloaded:
$ cockroach demo
Show range information for a row in a table
To show information about a row in a table, you must know the values of the columns in the row's primary key:
> SHOW INDEX FROM vehicles;
table_name | index_name | non_unique | seq_in_index | column_name | direction | storing | implicit
-------------+---------------------------------------+------------+--------------+-------------+-----------+---------+-----------
vehicles | primary | false | 1 | city | ASC | false | false
vehicles | primary | false | 2 | id | ASC | false | false
vehicles | primary | false | 3 | type | N/A | true | false
vehicles | primary | false | 4 | owner_id | N/A | true | false
vehicles | primary | false | 5 | creation_time | N/A | true | false
vehicles | primary | false | 6 | status | N/A | true | false
vehicles | primary | false | 7 | current_location | N/A | true | false
vehicles | primary | false | 8 | ext | N/A | true | false
vehicles | vehicles_auto_index_fk_city_ref_users | true | 1 | city | ASC | false | false
vehicles | vehicles_auto_index_fk_city_ref_users | true | 2 | owner_id | ASC | false | false
vehicles | vehicles_auto_index_fk_city_ref_users | true | 3 | id | ASC | false | true
(11 rows)
> SELECT city, id FROM vehicles LIMIT 5;
city | id
--------------+---------------------------------------
amsterdam | bbbbbbbb-bbbb-4800-8000-00000000000b
amsterdam | aaaaaaaa-aaaa-4800-8000-00000000000a
boston | 22222222-2222-4200-8000-000000000002
boston | 33333333-3333-4400-8000-000000000003
los angeles | 99999999-9999-4800-8000-000000000009
(5 rows)
> SHOW RANGE FROM TABLE vehicles FOR ROW (
'boston',
'22222222-2222-4200-8000-000000000002'
);
start_key | end_key | range_id | lease_holder | lease_holder_locality | replicas | replica_localities
----------------------------------------------------------------+---------------------------------------------------------+----------+--------------+-----------------------+----------+---------------------------
/"boston"/"\"\"\"\"\"\"B\x00\x80\x00\x00\x00\x00\x00\x00\x02" | /"boston"/"333333D\x00\x80\x00\x00\x00\x00\x00\x00\x03" | 57 | 1 | region=us-east1,az=b | {1} | {"region=us-east1,az=b"}
(1 row)
Show range information for a row by a secondary index
To show information about a row in a secondary index, you must know the values of the indexed columns:
> SHOW INDEX FROM vehicles;
table_name | index_name | non_unique | seq_in_index | column_name | direction | storing | implicit
-------------+---------------------------------------+------------+--------------+-------------+-----------+---------+-----------
vehicles | primary | false | 1 | city | ASC | false | false
vehicles | primary | false | 2 | id | ASC | false | false
vehicles | primary | false | 3 | type | N/A | true | false
vehicles | primary | false | 4 | owner_id | N/A | true | false
vehicles | primary | false | 5 | creation_time | N/A | true | false
vehicles | primary | false | 6 | status | N/A | true | false
vehicles | primary | false | 7 | current_location | N/A | true | false
vehicles | primary | false | 8 | ext | N/A | true | false
vehicles | vehicles_auto_index_fk_city_ref_users | true | 1 | city | ASC | false | false
vehicles | vehicles_auto_index_fk_city_ref_users | true | 2 | owner_id | ASC | false | false
vehicles | vehicles_auto_index_fk_city_ref_users | true | 3 | id | ASC | false | true
(11 rows)
> SELECT city, owner_id, id FROM vehicles@vehicles_auto_index_fk_city_ref_users LIMIT 5;
city | owner_id | id
--------------+--------------------------------------+---------------------------------------
amsterdam | bd70a3d7-0a3d-4000-8000-000000000025 | bbbbbbbb-bbbb-4800-8000-00000000000b
amsterdam | c28f5c28-f5c2-4000-8000-000000000026 | aaaaaaaa-aaaa-4800-8000-00000000000a
boston | 2e147ae1-47ae-4400-8000-000000000009 | 22222222-2222-4200-8000-000000000002
boston | 33333333-3333-4400-8000-00000000000a | 33333333-3333-4400-8000-000000000003
los angeles | 9eb851eb-851e-4800-8000-00000000001f | 99999999-9999-4800-8000-000000000009
(5 rows)
> SHOW RANGE FROM INDEX vehicles@vehicles_auto_index_fk_city_ref_users FOR ROW (
'boston',
'2e147ae1-47ae-4400-8000-000000000009',
'22222222-2222-4200-8000-000000000002'
);
start_key | end_key | range_id | lease_holder | lease_holder_locality | replicas | replica_localities
------------+---------+----------+--------------+-----------------------+----------+---------------------------
NULL | NULL | 53 | 1 | region=us-east1,az=b | {1} | {"region=us-east1,az=b"}
See also
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