Partitions Performance with MySQL 5.1 and 5.5

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Giuseppe Maxia
MySQL Community
Team Lead
Sun Microsystems
Wednesday, 13 January 2010

Who's this guy?

about me
2


Giuseppe Maxia
• a.k.a. The Data Charmer
• MySQL Community Team Lead
• Long time hacking with MySQL features
• Formerly, database consultant, designer, coder.
• A passion for QA
• An even greater passion for open source
• ... and community
• Passionate blogger
• http://datacharmer.blogspot.com 3


MySQL 5.1 GA

4


MySQL 5.1 GA

5


Defining the problem

YOUR
NEEDS 6


The problem(s)
• Too much data
• Not enough RAM
• Historical data
• Growing data
• Rotating data

7


Too much data

data

8


Not enough RAM

RAM

INDEXES
data INDEXES

9


Not enough RAM

INDEXES
RAM
data INDEXES

10


MySQL 5.1 partitions

WHAT
11


What is it?
• Logical splitting of tables
• Transparent to user

12


Logical splitting
• No need to create separate tables
• No need to move chunks of data across files

13



TRANSPARENT SQL
14


COMPARED TO MERGE TABLES

MERGE TABLE • separate tables
• risk of duplicates
• insert in each table
• no constraints

15


COMPARED TO MERGE TABLES

PARTITIONED TABLE • One table
• No risk of duplicates
• insert in one table
• constraints enforced

16


Wait a minute ...
• WHAT THE HELL DOES "LOGICAL SPLIT"
REALLY MEANS?
• LET ME EXPLAIN ...

17


Physical partitioning (1)
• Take a map

18


• cut it into pieces

19


• What you have, is several different pieces

20


• If you want the map back, you need some
application (adhesive tape) and you may get it
wrong

21


Logical partitioning (1)
• Take a map

22


• fold it to show the piece you need

23


• what you have is still a map, even if you see only
one part.

24


• if you unfold the map, you still have the whole thing

25


What partitions can do
• logical split
• but you can also split the data physically
• granular partition (subpartitioning)
• different methods (range, list, hash, key)

26


Partition pruning
1a - unpartitioned table - SINGLE RECORD

select *
from
table_name
where colx =
120


Partition pruning
1b - unpartitioned table - SINGLE RECORD

select *
from
table_name
where colx =
350


Partition pruning
1c - unpartitioned table - RANGE

select *
from
table_name
where colx
between 120
and 230


Partition pruning
2a - table partitioned by colx - SINGLE REC
1-99

100-199
select *
from
200-299 table_name
where colx =
300-399 120
400-499

500-599

Partition pruning
2b - table partitioned by colx - SINGLE REC
1-99

100-199
select *
from
200-299 table_name
where colx =
300-399 350
400-499

500-599

Partition pruning
2c - table partitioned by colx - RANGE
1-99

select *
100-199 from
table_name
200-299
where colx
300-399 between 120
and 230
400-499

500-599


WHY
33


4 main reasons to use partitions
• To make single inserts and selects faster
• To make range selects faster
• To help split the data across different paths
• To store historical data efficiently
• If you need to delete large chunks of data
INSTANTLY

34



HOW
35


HOW TO MAKE PARTITIONS

•RTFM ...
• No, seriously, the manual has everything
• But if you absolutely insist ...

36


CREATE TABLE t1 (
id int
) ENGINE=InnoDB
# or MyISAM, ARCHIVE
PARTITION BY RANGE (id)
(
PARTITION P1 VALUES LESS THAN (10),
PARTITION P2 VALUES LESS THAN (20)
) 37


CREATE TABLE t1 (
id int
) ENGINE=InnoDB
PARTITION BY LIST (id)
(
PARTITION P1 VALUES IN (1,2,4),
PARTITION P2 VALUES IN (3,5,9)
)
38


CREATE TABLE t1 (
id int not null primary key
) ENGINE=InnoDB
PARTITION BY HASH (id)
PARTITIONS 10;

39


CREATE TABLE t1 (
id int not null primary key
) ENGINE=InnoDB
PARTITION BY KEY ()
PARTITIONS 10;

40


Limitations
• Can partition only by INTEGER columns
• OR you can partition by an expression, which must
return an integer
• Maximum 1024 partitions

• If you have a Unique Key or PK, the partition
column must be part of that key
• No Foreign Key support
• No Fulltext or GIS support
41


PARTITIONING BY DATE
CREATE TABLE t1 (
d date
) ENGINE=InnoDB
PARTITION BY RANGE (year(d))
(
PARTITION P1 VALUES
LESS THAN (1999),
PARTITION P2 VALUES
LESS THAN (2000) 42

)

PARTITIONING BY DATE
CREATE TABLE t1 (
d date
) ENGINE=InnoDB
PARTITION BY RANGE (to_days(d))
(
PARTITION P1 VALUES
LESS THAN (to_days('1999-01-01')),
PARTITION P2 VALUES
LESS THAN (to_days('2000-01-01'))
43

)


WHEN
44


When to use partitions?
• if you have large tables
• if you know that you will always query for the
partitioning column
• if you have historical tables that you want to purge
quickly
• if your indexes are larger than the available RAM

45



HANDS
ON 46


components used for testing
• MySQL Sandbox
> created MySQL instances in seconds
> http://launchpad.net/mysql-sandbox

• MySQL Employees Test Database
> has ~ 4 mil records in 6 tables
> http://launchpad.net/test-db

• Command line ability
> fingers
> ingenuity
47


employees test database

48


How many partitions
from information_schema.partitions
+-------+-----------------+----------+
| pname | expr | descr |
+-------+-----------------+----------+
| p01 | year(from_date) | 1985 |

...
...
| p19 | year(from_date) | MAXVALUE |
+-------+-----------------+----------+ 49


How many records
select count(*) from salaries;
+----------+
| count(*) |
+----------+
| 2844047 |
+----------+
1 row in set (0.01 sec)

50


How many records in 1998
not partitioned
select count(*) from salaries
where from_date between
'1998-01-01' and '1998-12-31';
+----------+
| count(*) |
+----------+
| 247489 |
+----------+

# NOT PARTITIONED 51


PARTITIONED
'1998-01-01' and '1998-12-31';
+----------+
| count(*) |
+----------+
| 247489 |
+----------+

# partition p15
52


not partitioned
'1999-01-01' and '1999-12-31';
+----------+
| count(*) |
+----------+
| 260957 |
+----------+

# NOT PARTITIONED
53


PARTITIONED
'1999-01-01' and '1999-12-31';
+----------+
| count(*) |
+----------+
| 260957 |
+----------+

# partition p16
54


Deleting 1998 records
not partitioned
delete from salaries where
from_date between '1998-01-01'
and '1998-12-31';
Query OK, 247489 rows affected
(19.13 sec)

# NOT PARTITIONED

55


Deleting 1998 records
partitioned
alter table salaries drop
partition p15;
Query OK, 0 rows affected (1.35
sec)

56



LEVERAGING
REPLICATION
57


Replication schemes
INNODB INNODB
NOT NOT
MASTER PARTITIONED PARTITIONED

concurrent insert SLAVE
concurrent read

INNODB MyISAM
PARTITIONED PARTITIONED
BY RANGE BY RANGE
SLAVE SLAVE
58
concurrent batch processing large batch processing

Replication schemes
concurrent insert
INNODB
PARTITIONED
MASTER

INNODB
NON
MyISAM PARTITIONED
SLAVE PARTITIONED
SLAVE
59
batch processing concurrent reads


PITFALLS
60


Expressions
• Partition by function
• Search by column

61


WRONG
PARTITION BY RANGE(year(from_date))

select count(*) from salaries where
year(from_date) = 1998;
+----------+
| count(*) |
+----------+
| 247489 |
+----------+
62


RIGHT
PARTITION BY RANGE(year(from_date))

select count(*) from salaries where
from_date between '1998-01-01' and
'1998-12-31';
+----------+
| count(*) |
+----------+
| 247489 |
+----------+
63


EXPLAIN
explain partitions select count(*)
from salaries where year(from_date)
= 1998G
***** 1. row ****
id: 1
select_type: SIMPLE
table: salaries
partitions:
p01,p02,p03,p04,p05,p06,p07,p08,p09
,p10,p11,p12,p13,p14,p15,p16,p17,p1
8,p19
type: index 64

...

EXPLAIN
explain partitions select count(*)
from salaries where from_date
between '1998-01-01' and
'1998-12-31'G
***** 1. row ****
id: 1
select_type: SIMPLE
table: salaries
partitions: p14,p15
...

65



BENCHMARKS

66


Partitions benchmarks (laptop)

engine storage
(MB)
innodb 221
myisam 181
archive 74
innodb partitioned (whole) 289
innodb partitioned (file per table) 676
myisam partitioned 182
archive partitioned 72


Benchmarking results (laptop)
engine query year query year
2000 2002
InnoDB 1.25 1.25

MyISAM 1.72 1.73

Archive 2.47 2.45

InnoDB partitioned 0.24 0.10
whole
InnoDB Partitioned 0.45 0.10
(file per table)
MyISAM partitioned 0.18 0.12

Archive partitioned 0.22 0.12


Partitioning storage (huge server)

engine storage
(GB)
innodb (with PK) 330
myisam (with PK) 141
archive 13
innodb partitioned (no PK) 237
myisam partitioned (no PK) 107
archive partitioned 13


Benchmarking results (huge server)
engine 6 month range
InnoDB 4 min 30s
MyISAM 25.03s
Archive 22 min 25s
InnoDB partitioned by month 13.19
MyISAM partitioned by year 6.31
MyISAM partitioned by month 4.45
Archive partitioned by year 16.67
Archive partitioned by month 8.97



TOOLS
71


The partition helper
• The INFORMATION_SCHEMA.PARTITIONS table
• The partition helper
> http://datacharmer.blogspot.com/2008/12/partition-
helper-improving-usability.html
> A Perl script that creates partitioning statements

• ... anything you are creating right now :)

72



TIPS
73


TIPS
• For large table ( indexes > available RAM)
> DO NOT USE INDEXES
> PARTITIONS ARE MORE EFFICIENT

74


TIPS
• Before adopting partitions in production, benchmark!
• you can create partitions of different sizes
> in historical tables, you can partition
– current data by day
– recent data by month
– distant past data by year
> ALL IN THE SAME TABLE!
• If you want to enforce a constraint on a integer
column, you may set a partition by list, with only the
values you want to admit.
75


TIPS
• For large historical tables, consider using ARCHIVE
+ partitions
> You see benefits for very large amounts of data ( > 500
MB)
> Very effective when you run statistics
> Almost the same performance of MyISAM
> but 1/10 of storage

76



NEW
FEATURES
77


MySQL 5.5 enhancements
• PARTITION BY RANGE COLUMNS
• PARTITION BY LIST COLUMNS
• TO_SECONDS

78


R E
CREATE TABLE t ( FO
dt date
B E 5.1
)
PARTITION BY RANGE (TO_DAYS(dt))
(
PARTITION p01 VALUES LESS THAN
(TO_DAYS('2007-01-01')),
(TO_DAYS('2008-01-01')),
(TO_DAYS('2009-01-01')),
(MAXVALUE));
79


R E
FO
SHOW CREATE TABLE t G B E 5.1
Table: t
Create Table: CREATE TABLE `t` (
`dt` date DEFAULT NULL
) ENGINE=MyISAM DEFAULT
CHARSET=latin1
/*!50100 PARTITION BY RANGE (TO_DAYS
(dt))
(PARTITION p01 VALUES LESS THAN
(733042) ENGINE = MyISAM,
[…]
80


E R
CREATE TABLE t (
FT
dt date
A 5.5
)
PARTITION BY RANGE COLUMNS (dt)
(
('2007-01-01'),
('2008-01-01'),
('2009-01-01'),
(MAXVALUE)); 81


E R
FT
SHOW CREATE TABLE t
Table: t A 5.5
Create Table: CREATE TABLE `t` (
`dt` date DEFAULT NULL
) ENGINE=MyISAM DEFAULT
CHARSET=latin1
/*!50500 PARTITION BY RANGE
COLUMNS(dt)
(PARTITION p01 VALUES LESS THAN
('2007-01-01') ENGINE = MyISAM,
[…]
82


MySQL 5.5 - Multiple columns
CREATE TABLE t (
a int,
b int
)PARTITION BY RANGE COLUMNS (a,b)
(
(10,1),
(10,10),
(10,20),
(MAXVALUE, MAXVALUE)); 83


partition definition
by range (a,b)
records partition LESS THAN
a b p01 10 10
1 10 p02 10 20
10 9 p03 10 30
10 10 p04 10 MAXVALUE
10 11 p05 MAXVALUE MAXVALUE


by range (a,b)
records
partition LESS THAN
a b
p01 10 10
1 10
p02 10 20
10 9 p03 10 30

(1,10) < (10,10) ?

(a < 10)
OR
((a = 10) AND (b < 10))
(1 < 10)
OR TRUE
((1 = 10) AND (10 < 10))

by range (a,b)
a b p01 10 10
1 10 p02 10 20
10 9 p03 10 30

(10,9) < (10,10) ?

(a < 10)
OR
((a = 10) AND (b < 10))
(10 < 10)
OR TRUE
((10 = 10) AND (9 < 10))

by range (a,b)
a b p01 10 10
1 10 p02 10 20
10 9 p03 10 30

(10,10) < (10,10) ?

(a < 10)
OR
((a = 10) AND (b < 10))
(10 < 10)
OR FALSE
((10 = 10) AND (10 < 10))

by range (a,b)
a b p01 10 10
1 10 p02 10 20
10 9 p03 10 30

(10,10) < (10,20) ?

(a < 10)
OR
((a = 10) AND (b < 20))
(10 < 10)
OR TRUE
((10 = 10) AND (10 < 20))

CREATE TABLE employees (
emp_no int(11) NOT NULL,
birth_date date NOT NULL,
first_name varchar(14) NOT NULL,
last_name varchar(16) NOT NULL,
gender char(1) DEFAULT NULL,
hire_date date NOT NULL
) ENGINE=MyISAM
PARTITION BY RANGE COLUMNS(gender,hire_date)
(PARTITION p01 VALUES LESS THAN ('F','1990-01-01'),
PARTITION p02 VALUES LESS THAN ('F','2000-01-01'),
PARTITION p03 VALUES LESS THAN ('F',MAXVALUE),
PARTITION p04 VALUES LESS THAN ('M','1990-01-01'),
PARTITION p05 VALUES LESS THAN ('M','2000-01-01'),
PARTITION p06 VALUES LESS THAN ('M',MAXVALUE),
PARTITION p07 VALUES LESS THAN (MAXVALUE,MAXVALUE)

89


• TRUNCATE PARTITION
• TO_SECONDS()

90


More new features

COMING
SOON
91


PLANNED FEATURES - DISCUSS
• ALTER TABLE t1 EXCHANGE PARTITION p WITH
TABLE t2

• SELECT * FROM T (PARTITION p) WHERE ...

92


Read more
• articles
http://dev.mysql.com

• official docs
http://dev.mysql.com/doc

• my blog
http://datacharmer.blogspot.com
93


Thank you!

Giuseppe Maxia
http://datacharmer.blogspot.com
datacharmer@sun.com


BONUS
SLIDES
95



ANNOYANCES
96


Annoyances with partitions
• CREATE TABLE STATEMENT hard to read

97


• hard to read (FIXED!! in 5.1.31)

98


• CREATE TABLE only keeps the result of the
expression for each partition.
• (you can use the information_schema to ease the
pain in this case)

99


CREATE TABLE t1 (
d date
) ENGINE=InnoDB
PARTITION BY RANGE (to_days(d))
(
PARTITION P1 VALUES
LESS THAN (to_days('1999-01-01')),
PARTITION P2 VALUES
LESS THAN (to_days('2000-01-01'))
100

)

CREATE TABLE `t1` (
`d` date DEFAULT NULL
) ENGINE=InnoDB DEFAULT
CHARSET=latin1
/*!50100 PARTITION BY RANGE (to_days
(d))
(PARTITION P1 VALUES LESS THAN
(730120) ENGINE = InnoDB,
PARTITION P2 VALUES LESS THAN
(730485) ENGINE = InnoDB) */
101


Fixing annoyances with partitions
select partition_name part,
partition_expression expr,
partition_description val
from information_schema.partitions
where table_name='t1';
+------+------------+--------+
| part | expr | val |
+------+------------+--------+
| P1 | to_days(d) | 730120 |
| P2 | to_days(d) | 730485 |
102
+------+------------+--------+

fixing annoyances with partitions
select partition_name part ,
partition_expression expr, from_days
(partition_description) val from
information_schema.partitions where
table_name='t1';
+------+------------+------------+
| part | expr | val |
+------+------------+------------+
| P1 | to_days(d) | 1999-01-01 |
| P2 | to_days(d) | 2000-01-01 |
+------+------------+------------+
103


Partitions Performance with MySQL 5.1 and 5.5

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