ALTER TABLE t ADD PARTITION needs 'PARTITIONS n' for KEY and HASH partitioning, just a number is not parsed.

[mjonss]

Change Request

Please answer the following questions before submitting your issue. Thanks!

1. Describe what you find is inappropriate or missing in the existing docs.
   In https://docs.pingcap.com/tidb/stable/partitioned-table it says:

Increase the number of partitions using the `ALTER TABLE <table name> ADD PARTITION <number of partitions to increase by | (additional partition definitions)>` statement.

But it needs to be

Increase the number of partitions using the `ALTER TABLE <table name> ADD PARTITION {PARTITIONS <number of partitions to increase by> | (<additional partition definitions>)}` statement.

I.e. ALTER TABLE t ADD PARTITION 2 is not valid syntax, while ALTER TABLE t ADD PARTITION PARTITIONS 2 is.

2. Describe your suggestion or addition.

3. Provide some reference materials (such as documents and websites) if you could.
   https://docs.pingcap.com/tidb/stable/partitioned-table
   https://dev.mysql.com/doc/refman/8.0/en/partitioning-management-hash-key.html

[dveeden]

Did you create a PR for this?