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COUNT SHARDING RULE

Description

The COUNT SHARDING RULE syntax is used to query the number of sharding rules for specified database.

Syntax

CountShardingRule::=
  'COUNT' 'SHARDING' 'RULE' ('FROM' databaseName)?

databaseName ::=
  identifier

Supplement

  • When databaseName is not specified, the default is the currently used DATABASE. If DATABASE is not used, No database selected will be prompted.

Return value description

Column Description
rule_name rule type
database the database to which the rule belongs
count the number of the rule

Example

  • Query the number of sharding rules for specified database.
COUNT SHARDING RULE FROM sharding_db;

mysql> COUNT SHARDING RULE FROM sharding_db;
+--------------------------+----------------+-------+
| rule_name                | database       | count |
+--------------------------+----------------+-------+
| sharding_table           | sharding_db    | 2     |
| sharding_table_reference | sharding_db    | 2     |
| broadcast_table          | sharding_db    | 0     |
+--------------------------+----------------+-------+
3 rows in set (0.00 sec)
  • Query the number of sharding rules for current database.
COUNT SHARDING RULE;

mysql> COUNT SHARDING RULE;
+--------------------------+----------------+-------+
| rule_name                | database       | count |
+--------------------------+----------------+-------+
| sharding_table           | sharding_db    | 2     |
| sharding_table_reference | sharding_db    | 2     |
| broadcast_table          | sharding_db    | 0     |
+--------------------------+----------------+-------+
3 rows in set (0.00 sec)

Reserved word

COUNT, SHARDING, RULE, FROM