MDEV-26471 Syntax extension: do not require PARTITION keyword in partition definition

Instead of

  create or replace table t1 (x int)
  partition by range(x) (
    partition p1 values less than (10),
    partition pn values less than maxvalue);

it should be possible to type in shorter form:

  create or replace table t1 (x int)
  partition by range(x) (
    p1 values less than (10),
    pn values less than maxvalue);

As above examples demonstrate, make PARTITION keyword in partition
definition optional.

mysql-test/main/partition_alter.result

@@ -201,3 +201,67 @@ pk
 delete from t1;
 drop table t1;
 # End of 10.3 tests
+create or replace table t1 (x int primary key)
+partition by range(x) (
+p1 values less than (10),
+partition p2 values less than (20),
+p3 values less than (30),
+partition p4 values less than (40),
+p5 values less than (50),
+pn values less than maxvalue);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) NOT NULL,
+  PRIMARY KEY (`x`)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+ PARTITION BY RANGE (`x`)
+(PARTITION `p1` VALUES LESS THAN (10) ENGINE = MyISAM,
+ PARTITION `p2` VALUES LESS THAN (20) ENGINE = MyISAM,
+ PARTITION `p3` VALUES LESS THAN (30) ENGINE = MyISAM,
+ PARTITION `p4` VALUES LESS THAN (40) ENGINE = MyISAM,
+ PARTITION `p5` VALUES LESS THAN (50) ENGINE = MyISAM,
+ PARTITION `pn` VALUES LESS THAN MAXVALUE ENGINE = MyISAM)
+create or replace table t1 (x int)
+partition by list(x) (
+partition p1 values in (2, 3, 4),
+partition p2 values in (12, 13, 14),
+partition p3 values in (22, 23, 24),
+p4 values in (32, 33, 34),
+p5 values in (42, 43, 44),
+pn values in (52, 53, 54));
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `x` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+ PARTITION BY LIST (`x`)
+(PARTITION `p1` VALUES IN (2,3,4) ENGINE = MyISAM,
+ PARTITION `p2` VALUES IN (12,13,14) ENGINE = MyISAM,
+ PARTITION `p3` VALUES IN (22,23,24) ENGINE = MyISAM,
+ PARTITION `p4` VALUES IN (32,33,34) ENGINE = MyISAM,
+ PARTITION `p5` VALUES IN (42,43,44) ENGINE = MyISAM,
+ PARTITION `pn` VALUES IN (52,53,54) ENGINE = MyISAM)
+create or replace table t1 (x int)
+partition by list(x) (
+partition partition p1 values in (2, 3, 4),
+pn values in (52, 53, 54));
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'partition p1 values in (2, 3, 4),
+pn values in (52, 53, 54))' at line 3
+create or replace table t1 (x int)
+partition by list(x) (
+partition partition values in (2, 3, 4),
+pn values in (52, 53, 54));
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'partition values in (2, 3, 4),
+pn values in (52, 53, 54))' at line 3
+create or replace table t1 (x int)
+partition by list(x) (
+partition values in (2, 3, 4),
+pn values in (52, 53, 54));
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'in (2, 3, 4),
+pn values in (52, 53, 54))' at line 3
+create or replace table t1 (x int)
+partition by list(x) (
+partitio values in (2, 3, 4),
+pn values in (52, 53, 54));
+drop table t1;

mysql-test/main/partition_alter.test

@@ -186,3 +186,50 @@ delete from t1;
 drop table t1;
 
 --echo # End of 10.3 tests
+
+create or replace table t1 (x int primary key)
+partition by range(x) (
+  p1 values less than (10),
+  partition p2 values less than (20),
+  p3 values less than (30),
+  partition p4 values less than (40),
+  p5 values less than (50),
+  pn values less than maxvalue);
+
+show create table t1;
+
+create or replace table t1 (x int)
+partition by list(x) (
+  partition p1 values in (2, 3, 4),
+  partition p2 values in (12, 13, 14),
+  partition p3 values in (22, 23, 24),
+  p4 values in (32, 33, 34),
+  p5 values in (42, 43, 44),
+  pn values in (52, 53, 54));
+
+show create table t1;
+
+--error ER_PARSE_ERROR
+create or replace table t1 (x int)
+partition by list(x) (
+  partition partition p1 values in (2, 3, 4),
+  pn values in (52, 53, 54));
+
+--error ER_PARSE_ERROR
+create or replace table t1 (x int)
+partition by list(x) (
+  partition partition values in (2, 3, 4),
+  pn values in (52, 53, 54));
+
+--error ER_PARSE_ERROR
+create or replace table t1 (x int)
+partition by list(x) (
+  partition values in (2, 3, 4),
+  pn values in (52, 53, 54));
+
+create or replace table t1 (x int)
+partition by list(x) (
+  partitio values in (2, 3, 4),
+  pn values in (52, 53, 54));
+
+drop table t1;

sql/sql_yacc.yy

@@ -4707,8 +4707,13 @@ part_def_list:
         | part_def_list ',' part_definition {}
         ;
 
+opt_partition:
+          /* empty */
+          | PARTITION_SYM
+          ;
+
 part_definition:
-          PARTITION_SYM
+          opt_partition
           {
             partition_info *part_info= Lex->part_info;
             partition_element *p_elem= new (thd->mem_root) partition_element();