MySQL crash course by moshe kaplan

The VP R&D Open Seminar

MySQL Crash Course
From basics to experts
mokplan@gmail.com
http://top-performance.blogspot.com


WHY WE CHOSE MYSQL?


Who is Using MySQL?

3

Who is Behind MySQL


What MySQL is Made of?

5
http://dev.mysql.com/tech-resources/articles/mysql_5.0_psea1.html

MySQL Limitations

50-150M Records/Table
50-5000 SELECT Statements/Second

6

Why Do I Care?
From 0 to 100 (US mass adaptation)
Phone: 100 yrs
Radio: 40 yrs
TV: 30 yrs
Mobile: 20 yrs
Internet: 10 yrs
Facebook: 2 yrs

7

100K New Users/Week

8


WHAT MYSQL IS MADE OF?


MySQL Structure
Daemon
/var/lib/mysql
ibdata1
ib_logfile0, Ib_logfile1
/mysql
/database
/performance_schema
/etc/my.cnf


What to Install
wget mysql_package
yum –y localinstall mysql_package

The Packages:
Devel+Client+Server
Relevant platform (x86/x64)
Relevant operating system


MySQL Installation



DATABASE LOGICAL DESIGN
(OR ERD)


Instances, Schemas and inside information


1:Many

schoolId: schoolId:
Primary Key Foreign Key


Many:Many

?: ?:
Primary Key Foreign Key


Many:Many in Practice

testId: testId, studentId:
Primary Key studentId: Primary Key
Foreign Key


Design a Student Information System ERD



FROM ERD TO A DATABASE


Connect to the Database


Create a Schema/Database


Create a Table


Implement the a Student Information System ERD



SQL: DDL


Databases Manipulation
SHOW DATABASES;
CREATE DATABASE mydb;
DROP DATABASE mydb;
USE mydb;


Tables Manipulation
SHOW TABLES;
CREATE TABLE users (
id int,
INDEX users_id (id)
);
DROP TABLE users;
ALTER TABLE users ADD INDEX IX_id (id);
ALTER TABLE users DROP INDEX IX_id;



SQL: DML


SELECT
SELECT table.field, table.*
FROM table
WHERE table.field = 123
ORDER BY field1, field2 DESC


SELECT + Join
SELECT c.*, u.*
FROM classes c
INNER JOIN users u
ON c.teacherId = u.id


LEFT JOIN


GROUP BY
SELECT gender, count(id)
FROM users
WHERE gender = ‘M’
GROUP BY gender
HAVING count(id) > 10


UNION
SELECT id
FROM users
WHERE gender = ‘M’
UNION ALL
SELECT id
FROM users
WHERE gender = ‘F’
ORDER BY id;


UPDATE
UPDATE users
SET gender = ‘M’
WHERE gender IS NULL;


INSERT
INSERT INTO users (gender)
VALUES (‘M’);

INSERT INTO users (gender)
SELECT gender
FROM users
WHERE gender = ‘M’;


DELETE
DELETE
FROM users
WHERE gender = ‘M’;



MySQL Authentication and Authorization

SECURITY


Root User
First Time
mysqladmin -u root password NEWPASSWORD
Nth Time
mysqladmin -u root -p'oldpassword' password
newpass
How to enter
Mysql –uuser_name –ppassword –D
database_name
-h host_name/ip -A


Users Table
mysql> SELECT * FROM mysql.user limit 1G
*************************** 1. row ***************************
Host: localhost
User: root
Password: *4FB5C598BC3FF56E262F863A715F8CB2976A9C69
Select_priv: Y
Insert_priv: Y
Update_priv: Y
Delete_priv: Y
Create_priv: Y
Drop_priv: Y
….
1 row in set (0.00 sec)


Create a Users and Provide Permissions
-- Create a user w/ password
CREATE USER 'readonly'@'%' IDENTIFIED BY
‘sakexkas';
-- Grant Permissions
GRANT select ON my_db.* to 'readonly'@'%';
GRANT ALL PRIVILEGES ON *.* to
‘master_user’@’%’ WITH GRANT OPTION;
FLUSH PRIVILEGES;

-- Beware of too complex passwords



MYSQL AND LINUX ISSUES


Built in Linux Security Measures
IP TABLES
sudo /etc/init.d/iptables stop
sudo yum –y remove iptables
Configure the relevant rules
SELinux
sudo echo 0 > /selinux/enforce
vi /etc/selinux/config: SELINUX=enforcing  SELINUX=disabled
Files Limit (Table Partitioning)
/etc/security/limits.conf
mysql soft nofile 8192
mysql hard nofile 8192
my.cnf:
open_files_limit = 8192


Disk Resizing
http://top-
performance.blogspot.com/2012/02/do-you-
need-more-disk-space-for-mysql.html


Create a Master/Slave configuration



HIGH AVAILABILITY
ARCHITECTURES


Master/Slave


Master/Master

?

Show Status (1)
mysql> show slave statusG
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 10.12.12.167
Master_User: repl
Master_Port: 3306
Connect_Retry: 60

Master_Log_File: master.000094
Read_Master_Log_Pos: 167250867
Relay_Log_File: mysqld-relay-bin.000137
Relay_Log_Pos: 167251010

Relay_Master_Log_File: master.000094
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table: mysql.%,information_schema.%


Show Status (2)
Last_Errno: 0
Last_Error:
Skip_Counter: 0

Exec_Master_Log_Pos: 167250867
Relay_Log_Space: 167251310
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1


Skip
DON’T DO THAT unless you have to!
The Process:
STOP SLAVE;
SET GLOBAL SQL_SLAVE_SKIP_COUNTER =
1;
START SLAVE;
SHOW SLAVE STATUSG


How to Implement?
Stop a Master and record position
Copy a Master (instance/disk) to a Slave
Start the Master
Change slave server-id
SET MASTER HOST …
START SLAVE
Verify
Or…
http://top-performance.blogspot.co.il/2012/03/how-to-
setup-mysql-replication-in-11.html



SCALE-ABLE ARCHITECTURES


Do You Remember?

53

Strategy A: Sharding

54

Strategy B: In Memory Databases

55

700 Inserts/Sec

In Memory Engine

3000 Inserts/Sec

Amazon AWS

Standard InnoDB Engine

Large Instance 700 Inserts/Sec

56

IMDB - Implementation

57

Lessons
Cache: MySQL IMDB
HA: MySQL Replication
Persistence: Periodic 5min Batch
Scalability: Sharding

4 Bill Req/Day using 25 machines (2000/s)

58

Strategy C: MapReduce

59

Strategy D: NoSQL
insert
get
multiget
remove
truncate

<Key, Value>
http://wiki.apache.org/cassandra/API

60

When Should I Choose NoSQL?

Eventually Consistent
Document Store
Key Value

http://guyharrison.squarespace.com/blog/tag/nosql

61

Sharding Again

62

Vertical Sharding

63

Horizontal Sharding
Static Hashing
Complex growth Mod 10 = 0

Mod 10 = 1
Simple
Mod 10 = 2

Mod 10 = 3

Mod 10 = 4

Mod 10 = 5

Mod 10 = 6

Mod 10 = 7

Mod 10 = 8

Mod 10 = 9

64

Horizontal Sharding
Key locations are defined in a directory
Simple growth
Directory is SPOF

65

Horizontal Sharding
Static Hashing with Directory Mapping
Simple Growth
Small Directory still SPOF

Mod 1000 = 4

66

Horizontal Sharding
Each key signed by DB#
generated on creation
Simple growth
New key generation is SPOF

67

Limitations: Reporting

68

Best Practices
$connection =
new_db_connection("customer://1234");
$statement =
$connection->prepare(
$sql_statement,
$params
);
$result =
$statement->execute();

69


BACKUP AND RESTORE


Options
mysqldump
Physical disk copy
3rd Party solution: XtraDB, amanda


Backup Your Server



HANDLING PROBLEMS


Error Log
Get the Location:
[/]$ sudo more /etc/my.cnf | grep -i error
log-error=/var/lib/mysql/log.err
Look for issues
[/]$ sudo tail -n 20 /var/lib/mysql/log.err
121025 13:24:23 InnoDB: Initializing buffer pool, size = 128.0M
121025 13:24:23 InnoDB: Completed initialization of buffer pool
121025 13:24:24 InnoDB: highest supported file format is
Barracuda.
121025 13:24:25 InnoDB: Waiting for the background threads to
start



DEVOPS MYSQL


-e
mysql
-uuser
-ppassword
-Ddatabase
-hserver
-e”SELECT * FROM table;”


Import Data
mysql
-uuser
-ppassword
-Ddatabase
-hserver
< /dir/to/filename.sql


Export Data
mysqldump
-uuser
-ppassword
--databases database_name
--single-transaction --master-data=1 >
/path/to/backup/file.sql



MYSQL TUNING


my.cnf


mysqltuner


Slow Query
log-slow-queries = /var/log/mysql/mysql-
slow.log
long_query_time = 1
log-queries-not-using-indexes


Profiling
http://top-
performance.blogspot.co.il/2011/07/mysql-
statement-profiling.html


RAM Usage Optimization
Preferred: SizeOf(database) < SizeOf(RAM)
innodb_buffer_pool_size
50-70% of your RAM

85

Do We Utilize the Cache?
SHOW STATUS LIKE 'Qcache%';

Qcache_free_blocks 718
Qcache_free_memory 13004008
Qcache_hits 780759
Qcache_inserts 56292
Qcache_lowmem_prunes 0
Qcache_not_cached 3711
Qcache_queries_in_cache 1715
Qcache_total_blocks 4344

86

Cache Queries
query_cache_type = 1
query_cache_limit = 1M
query_cache_size = 16M

87

Buffer Optimization
key_reads/key_read_requests < 0.01
If not
Increase Key Buffer

88

CPU Optimization
thread_concurrency = 2 X #(CPU Cores)

89

Tune Your Server


Summary


What happens when mysql fails to start…
Create my.cnf
touch /etc/my.cnf
Create the error log
vi /etc/my.cnf
[mysqld]
log-error=/var/lib/mysql/log.err
If the my.cnf is already configured
more /etc/my.cnf | grep –i error
Restart mysql
Find the error
tail –n 50 /var/lib/mysql/log.err
In this case we kill all the mysql proceses
ps –aux | grep –i mysql
sudo kill process_id


The Bottom Line: Grow ∞

Thank you!
and Keep Performing!

Moshe Kaplan

93

MySQL crash course by moshe kaplan

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