mysql dba training session 22 partitioned tables in mysql

MySQL DBA Training Session 22. Partitioned Tables in MySQLRAM N SANGWAN

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Agenda for the Session

• MySQL Partitioning concepts

• Horizontal partitioning

• Vertical partitioning

• Choosing a Partitioning Method

• MySQL Partitioning Range partition

• MySQL Partitioning List Partition

• MySQL Partitioning Hash Partition

• MySQL Partitioning - Key Partition

• Partition Management Commands

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MySQL Partitioning concepts

• Partitioning is dividing up data in the database into distinct independent elements.

• Partitioning serves three main purposes

◦ data manageability

◦ performance

◦ availability

• Two ways to partition database tables

◦ Horizontal partitioning

◦ Vertical partitioning

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Advantages

• It allows you to split a table across multiple files, through the usage of a special partitioningrule called partitioning function.

• Partitioning can only take place in engines that support partitioning, engines like MyISAM orInnoDB and not like CSV or BlackHole.

• The big performance boost in database partition is that partitions that do not satisfy a certainrule are not scanned, this is called partition pruning.

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Horizontal partitioning

• Different rows are stored in different tables:

◦ customers with ID's less than 100,000 are stored in customers1 table and customers with ID's greaterare stored in customers2 table, etc.

• Table schemas are exactly the same (i.e.customer1 and customer2 tables have the sameschema), as if the table was cut into parts using a horizontal line.

• Archiving older data is commonly used example of horizontal partitioning, another techniqueusing horizontal partitioning is sharding which involves using separate servers to host similartypes of data:

◦ customer1 table would be held on server1and customer2 table would be held on server2.

• Horizontal partitioning is achieved manually using merge tables, as merge tables do notautomatically assign data to different underlying tables.

• Internal partitioning assigns records to a partition based on certain criteria.

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Vertical partitioning

• Different fields are stored in different tables:

◦ Customer names and email addresses might be stored in Customers and Addresses tables. Oftennormalization involves vertical partitioning, which means splitting up otherwise normalized data.

• In vertical partitioning the tables are split up vertically which means that the schemas will bedifferent but they contain similar records.

• This type of partitioning is also know as row splitting.

• Different physical storage could be used as well, you could even store pictures and largedocuments on the file system instead of in the database.

• Another option is to split up data in dynamic and static data tables, a static data table couldthen use query cache to improve performance.

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Choosing a Partitioning Method

• Range Partitioning• Data usually accessed by date

• Limited number of (primary) partitions needed

• Ordered Intelligent keys

• Supports Sub Partitions

• List Partitioning• Grouping data in partitions out of order (1,5,7 in partition x)

• Limited number of (primary) partitions needed

• Intelligent keys

• Supports Sub Partitions

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Choosing a Partitioning Method Contd..

• Hash Partitioning• Low maintenance

• Works with limited or large number of partitions

• Non-intelligent keys (can work with some cases of intelligent keys)

• Key Partitioning• Non-integer based partitioned keys (md5 hash)

• Low maintenance

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MySQL Range partition Example

CREATE TABLE t1 (

r_name VARCHAR(50) NOT NULL,

region_code TINYINT UNSIGNED NOT NULL

)

PARTITION BY RANGE( region_code ) (

PARTITION p0 VALUES LESS THAN (64),

PARTITION p1 VALUES LESS THAN (128),

PARTITION p3 VALUES LESS THAN MAXVALUE

);

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MySQL List Partition Example

CREATE TABLE employees (

id INT NOT NULL,

fname VARCHAR(30),

lname VARCHAR(30),

hired DATE NOT NULL DEFAULT '1970-01-01',

separated DATE NOT NULL DEFAULT '9999-12-31',

job_code INT,

store_id INT )

PARTITION BY LIST(store_id) (

PARTITION pNorth VALUES IN (16,15,3,5,6,9,17),

PARTITION pEast VALUES IN (1,2,8,10,11,19,20),

PARTITION pWest VALUES IN (7, 4,12,13,14,18) );


MySQL Partitioning Hash Partition:

CREATE TABLE employees (

id INT NOT NULL,

fname VARCHAR(30),

lname VARCHAR(30),

hired DATE NOT NULL DEFAULT '1970-01-01',

separated DATE NOT NULL DEFAULT '9999-12-31',

job_code INT,

store_id INT )

PARTITION BY HASH(store_id)

PARTITIONS 5;


MySQL Key Partition Example

CREATE TABLE k1 (

id INT NOT NULL PRIMARY KEY,

name VARCHAR(20))

PARTITION BY KEY()

PARTITIONS 4;

CREATE TABLE k1 (

id INT NOT NULL,

name VARCHAR(20),

UNIQUE KEY (id) )

PARTITION BY KEY()

PARTITIONS 4;


Partition Management Commands

• Add partitionalter table employees_by_region add partition (partition england values in (1,2),partition scotland values in (3,4)

);

• drop partitionalter table employees_by_region drop partition scotland;

• coalesce partitionalter table employees_hash coalesce partition 4;


Partition Management Commands Contd..

• Reorganize partitionalter table employees repair partition p0, p1;

• Analyze partitionalter table employees analyze partition 3;

• Check partitionalter table employees check partition 3;

• Optimize partitionalter table employees optimize partition p0, p1;

• Rebuild partitionalter table employees rebuild partition p0, p3;


Thank You


mysql dba training session 22 partitioned tables in mysql

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