how to drop partition without dropping data in MySQL?

Question

I have a table like:

create table registrations( 
id int not null auto_increment primary key,
name varchar(50),
mobile_number varchar(13)) 
engine=innodb 
partition by range(id) (
partition p0 values less than (10000),
partition p0 values less than (20000),
partition p0 values less than max value);

Not exactly like above but similar to that....

Now assume that my table has 200000 rows and now I want to remove partitions on the table and reorganize them in accordance to requirement without MAX VALUE in it.

Can any one help me to rearrange partition without dropping data or dropping table and recreating it ?

Answer 1

ALTER TABLE tbl REMOVE PARTITIONING;

来源： MySQL 参考手册中的 ALTER TABLE 语句

Answer 2

You can reorganize the partition p0 using the ALTER TABLE .. REORGANIZE PARTITION command.

http://dev.mysql.com/doc/refman/5.5/en/partitioning-management-range-list.html

If you intend to change the partitioning of a table without losing data, use ALTER TABLE ... REORGANIZE PARTITION

ALTER TABLE registrations 
REORGANIZE PARTITION p0 INTO (
    PARTITION p0 VALUES LESS THAN (10000),
    PARTITION p0 VALUES LESS THAN (20000)
);

Note that this will not make sense until you actually create several partitions eg

ALTER TABLE registrations 
REORGANIZE PARTITION p0 INTO (
    PARTITION p0 VALUES LESS THAN (10000),
    PARTITION p1 VALUES LESS THAN (20000),
    PARTITION p2 VALUES LESS THAN MAXVALUE
);

Have a look at RANGE partitioning in MySQL

If your partition p2 is becoming too large you can split it the same way.

Answer 3

Rearrange partitions doesn't require drop all existing partitions. You can specified the new partitioning in the ALTER TABLE syntax directly, and no data will be lost.

ALTER TABLE registrations
PARTITION by RANGE(id) (
PARTITION p1 VALUES LESS THAN (10000),
PARTITION p2 VALUES LESS THAN (20000),
PARTITION p3 VALUES LESS THAN (30000),
PARTITION p4 VALUES LESS THAN (40000),
PARTITION p5 VALUES LESS THAN (MAXVALUE);

PS Tested with MySQL 5.7.11

Answer 4

If you want to rearrange the data while keeping the partitions,
you can take a look at REORGANIZE PARTITION and COALESCE PARTITION clauses of ALTER TABLE
command.
http://dev.mysql.com/doc/refman/5.1/en/alter-table.html