ddl: fix 'alter table drop partition' check on hash partitioned table

[tiancaiamao]

What problem does this PR solve?

Before:

mysql> CREATE TABLE `t1` (
    ->   `a` int(11) DEFAULT NULL,
    ->   `b` varchar(64) DEFAULT NULL,
    ->   KEY `b` (`b`,`a`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
    -> PARTITION BY HASH( `a` )
    -> PARTITIONS 3;
Query OK, 0 rows affected (0.12 sec)

mysql> alter table t1 drop partition p2;
Query OK, 0 rows affected (0.11 sec)

mysql> select * from t1;
ERROR 2013 (HY000): Lost connection to MySQL server during query

After:

mysql> alter table t1 drop partition p2;
ERROR 1512 (HY000): DROP PARTITION can only be used on RANGE/LIST partitions

What is changed and how it works?

Forbid drop partition operation on a hash partitioned table.

Check List

Tests

• Unit test

Related changes

• Need to cherry-pick to the release branch

[tiancaiamao]

PTAL @crazycs520 @winkyao @zimulala

[tiancaiamao]

/run-all-tests

[winkyao]

LGTM

[codecov]

Codecov Report

Merging #10902 into master will increase coverage by 0.0208%.
The diff coverage is 100%.

@@               Coverage Diff                @@
##             master     #10902        +/-   ##
================================================
+ Coverage   81.0505%   81.0714%   +0.0208%     
================================================
  Files           419        419                
  Lines         88826      88892        +66     
================================================
+ Hits          71994      72066        +72     
+ Misses        11603      11601         -2     
+ Partials       5229       5225         -4

[tiancaiamao]

/run-all-tests

[zhouqiang-cl]

/rebuild

[tiancaiamao]

/rebuild

[crazycs520]

LGTM

[bb7133]

LGTM

[bb7133]

/run-unit-test