Transcript MySQL Would You Like Some Transactions With That Table? www.brianhitchcock.net Slides Are Available Oct 29, 2009 www.brianhitchcock.net Page 2

MySQL
Would You Like Some Transactions
With That Table?
www.brianhitchcock.net
Slides Are Available
Oct 29, 2009
www.brianhitchcock.net
Page 2
What Is MySQL?
Most popular open source RDBMS
 Open source means 'free'
 Really? No cost at all?
Widely used
 Sabre – airline reservations
 Google
 LinkedIn
What does Oracle DBA need to know?
 Many differences...
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Why Should I Care?
I'm an Oracle DBA
 MySQL means nothing to me
 It isn't a 'real' RDBMS
Why should I learn about MySQL?
 MySQL is being used by real businesses
 Can't hurt your employability
 Many jobs expect DBA to know multiple RDBMS
 Why not learn one that is widely used?
 And it's free – you can download and install right now!
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Oracle DBA Perspective
What will we look at?
 Installing
 Start/stop
 How database/tables stored
 Backups
 Transactions
 Storage engines
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My Message
Compare MySQL to Oracle
 Not to be critical of MySQL
 Not to praise Oracle
 Make Oracle DBAs aware
 How much we assume about RDBMS
 Because Oracle does things a certain way
 MySQL is very different
 Assuming it is like Oracle can cause serious problems
 Does your business understand the differences?
 The cost of being 'free'?
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MySQL Versions
MySQL Enterprise
 Have to buy support
MySQL Community Edition
 The 'free' version
MySQL Community Edition Preview Release
 Available for download
 Ready for prime time?
 Oracle doesn't offer 12g for trial download...
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MySQL Versions
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MySQL – Where Did It Come From?
Used to store web site logs
 Transactions
 What's that?
 If we lose some records
 So what?
 Supported by an individual
 Do your own thing
 Recovery
 Not to worry, plenty more web logs every day
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Some Differences – MySQL/Oracle
Oracle
 Database
 Schema
a group of database objects
 Database user
Maps to a database schema
MySQL
 Server
 Databases
Group of database objects
 Users don't map to database
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Some Differences – MySQL/Oracle
Storage engines
Transaction support
Performance
Hot backup
Binary logging and recovery
Table locking
Corruption
Misc.
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Storage Engines
MySQL gives you a choice
 Oracle, all transactional all the time (OATATT)
MySQL storage engines
 MyISAM (IBM, Indexed Sequential Access Method)
 Very fast read
 InnoDB
 Transactional, like Oracle
 Separate software, owned by Oracle
 Many others
 See next chart
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Storage Engines
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InnoDB Storage Engine
Imagine mixing
 MyISAM, InnoDB tables in a statement
 What does 'transactional' mean?
 What does “recovery” mean?
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CSV Storage Engine
CSV storage engine
 Stores data in text files
 Using comma-separated format
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Blackhole Storage Engine
My favorite
This is where we store all the data relating to the Raiders and
their 'Commitment to Excellence'
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Yeah, But...
No problem
 I'll just make all the tables InnoDB
Cool, but
 MySQL catalog (system?) tables are MyISAM
 Can't change them
 Table storage engine can be changed at any time
 Privileged users
 No one should do this, but...stuff happens
 Create table syntax
 Supports overriding default storage engine
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Transaction Support
MyISAM
 Default table type
 Table type of system databases
 Does not support transactions
 Example
 Writing to MyISAM tables and server crashes
 Who know what was and wasn't written to tables
 No recovery
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Performance
Many large MySQL servers in use
 Performance must be good
or good enough for 'free'
Optimizer
 Different storage engines
 How to optimize statement that has
 MyISAM tables
 InnoDB tables
 Does it support all storage engines you are using?
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Hot Backup
MySQL does not have this
 Backup option #1
 Shutdown server, copy all files, startup server
 Backup option #2
 Lock all tables
 Dump all data to a dump file
Dump file is set of SQL to recreate database
Very slow to recover
 Backup option #3
 Buy hot backup software product
Not free
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Binary Logging and Recovery
MySQL
 Default, no logging
 You can configure binary logging
 Three formats
 Statement-based
 Row-based
 Mixed
 Binary log filenames have format
 binlog.000001, binlog.000002, etc.
 You must apply them in correct order
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MySQL Binary Logs
MySQL does not have any way of knowing
when replaying the binary logs which
statements need to be executed and which are
already committed.
Oracle DBA doesn't worry about this
 Oracle checks and tells you which archived redo log
is needed next
 Oracle won't allow archived redo logs to be applied
out of order
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Binary Logging Formats
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Binary Log Issues
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Table Locking
MyISAM storage engine
 Does not support row level locking
 Table locks
 Performance?
InnoDB storage engine
 Supports row level locking
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Corruption
Oracle
 I have rarely seen any cases
 But all tables support transactions
MySQL
 What does it mean to rollback
 When different storage engines involved
 Some support transactions, some don't
 Some tables will be rolled back
Others won't
 Is this corruption?
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MySQL Corruption Issues
Good read
 Discusses corruption issues in MySQL engines
 I'm not saying this happens often
 But you need to be aware of these issues
 Another difference from Oracle
Different storage engines, different corruption mechanisms
http://www.mysqlperformanceblog.com/2006/07
/30/mysql-crash-recovery/
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MySQL Issues
Misc
 Referential Integrity
 Some storage engines support
 Triggers
 Row-level, not statement-level
 Directload
 Not supported
 Parallel Query
 Not supported
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MySQL Issues
White Paper
 Compares MySQL to PostgreSQL
 PostgreSQL, another open source RDBMS
 More like Oracle than MySQL
 Discusses issues with MySQL
 I'm not endorsing PostgreSQL
 But the whitepaper is very good
 Google
 PostgreSQL vs. MySQL A Comparison of Enterprise
Suitability
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MySQL Table Storage
MyISAM
 Each table has three files
 <filename>.frm – Data dictonary information
 <filename>.MYD – table data
 <filename>.MYI – table indexes
InnoDB
 Data and indexes in a tablespaces
 Made up of one or more datafiles
 Sound familiar?
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Documentation Online
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Documentation Online
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Documentation Online
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Talk Is Cheap
A little less conversation
 A little more action
Download and install MySQL to your laptop now
 Slides show the steps
 Windows
You will have a fully functional MySQL server
 Start learning right now
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Install MySQL – Windows
Windows Vista
 6.0 Service Pack 1
 Screenshots shown
Windows XP
 Professional Version 5.1
 Same steps
 Very minor differences in what you see
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Downloads?
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Downloads?
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Enterprise Version
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Community Version
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Windows Downloads
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
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Windows Installation
Uncheck
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Windows Installation
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Windows Installation
Check
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Windows Installation
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Windows Installation
mysql
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Windows Installation
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Accessing MySQL Windows
Click Start
 Programs
 MySQL
 MySQL Server 5.1
 MySQL Command Line Client
 Right-click
Send to
 Desktop (Create Shortcut)
Double-click desktop icon
 MySQL Command Line Client
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Accessing MySQL Windows
Shortcut created at installation
mysql
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mysql client utility
Similar to SQL*Plus
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Now What?
Stop, start MySQL server
What databases are available
 show databases;
Set default database
 use <dbname>
What tables are in the database
 show tables;
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Windows Vista
Stop/Start
 Services





Start
Settings
Control Panel
System and Maintenance
Administrative Tools
Services
 Scroll down to MySQL, highlight
 Upper left, options for Stop, Pause, Restart
 If MySQL is down, option to Start
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Windows XP
Stop/Start
 Command line
 net stop mysql, net start mysql
 Services




Start
Control Panel
Administrative Tools
Services
Services window
Scroll down to MySQL, highlight
Upper left, options for Stop, Pause, Restart
 If MySQL is down, option to Start
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System Databases
INFORMATION_SCHEMA
 Catalog database
MYSQL database
 User and privilege information
TEST
 For you to play in...
These databases are created at installation
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MySQL Server Configuration
Controlled by 'option' file(s)
 Similar to Oracle pfile or spfile
 SHOW VARIABLES
 See current values
Standard location(s)
 Search order
One of the most common problems
 Persons don't know where these files are
 Make changes that don't take affect
 Can't find the file or files
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Option File(s)
MySQL searches multiple locations
 Uses most recent value of each parameter
 How to know all files being scanned by MySQL?
 mysql –help
Note: dash dash help
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Option File
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Option File
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Option File
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Option File
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Option File
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MySQL Filesystem Layout
From option file (my.ini)
 basedir
 Where software is stored
 datadir
 Where table data is stored
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MySQL basedir
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MySQL basedir/bin
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MySQL datadir
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MySQL Log Files
General Query Log
 All client requests
Binary Log
 Statements that modify data
Slow Query Log
 Statements that take longer than 10 seconds
Error Log
 Server messages
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MySQL Log Files
Find log file locations
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Summary
MySQL is 'free'
 May need other products to make it work for you
 Hot backup for example
MySQL is widely used
MySQL is very different from Oracle
 DBA tasks and issues will be different
MySQL is not better or worse than Oracle
 Just very different
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The End?
You now have a MySQL server installed
No excuses
 Learn it, live it, love it
 Update your resume
Next?
 Multiple MySQL servers on same machine
 Replication
 etc.
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