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  • 1. A Brief Introduction to MySQL By Nishkam, Neeraj,Saurabh, Hrishikesh and Somesh
  • 2. Pointers
    • What is MySQL ? Its good features.
    • Installation guide.
    • Security and Privilege System
    • Compatibility with standards
    • Locks – an interesting feature
    • Table types
    • Some more salient features
    • Replication
  • 3. What Is MySQL?
    • A fast, reliable, easy-to-use, multi-user multi-threaded relational database system.
    • It is freely available and released under GPL (GNU General Public License ).
  • 4. Why Use MySQL ?
    • MySQL server can handle very large databases.
    • Offers rich and very useful set of functions.
    • Connectivity, speed and security make MySQL very suited for accessing database on a network.
    • A lot of contributed software available.
  • 5. What Does MySQL Offer ?
    • A privilege and password system that is very flexible and secure and allows host-based verification.
    • Multi-threaded request-handling using kernel thread.
    • Replication features.
    • Very actively developed.
    • Memory leak proof.
  • 6. Quick Installation Guide
    • tar –zxvf Mysql.x.xx.xx.tar.gz
    • cd Mysql-x.xx.xx.xx
    • ./configure –prefix=/usr/local/mysql
    • make
    • make install
    • scripts/mysql_install_db
    • safe_mysqld
    • Mysql –u root password ‘mypassword’
  • 7. Configuring MySql
    • --bindir=Dir specifies dir for binaries
    • --localstatedir=Dir data dir
    • --with-tcp-port=portno
    • --with-unix-sock-path=absolute-path
    • --with-mysqld-ldflag=-all-static
    • --with-charset=charset (default Latin1)
    • --with-low-memory
  • 8. Support
    • Works on many different platforms like FreeBSD , NetBSD , Linux 2.0+, Windows ’95, ’98, 2000 & NT, HP-UX etc
    • There are client tools and APIs available in c, c++, java, perl, python, php, Tcl
  • 9. Security in mysql
    • Issues that bother: eavesdropping,altering
    • Uses ACL’s (Access Control Lists) , also there’s some support for SSL connections
    • Has inbuilt methods for storing confidential data like passwords in encrypted form.
    • Access is restricted thru grant of privileges to users,hosts
  • 10. Privileges provided by mysql
    • The five tables: user,db,host,tables_priv,columns_priv
    • The privileges come into play only if there is a retrieval of data from the database, or updation of data in the database,e.g: select 1+1; calculator 
    • File privilege : load data infile, select …. Into outfile
  • 11. How the privilege system works
    • First reference to user followed by db and host , takes place during connection verification
    • Reference to tables_priv and columns_priv at data access stage
    • Ordering of user table on the basis of more specific host values first, followed by more specific user values.
    • For security purposes , mysql disallows host
    • addresses of the form :192.168.7.yahoo.com
  • 12. Some tips on security
    • Beneficial to invest in a firewall ; check using “telnet server_port 3306”
    • Do not rely on the data entered by the user, he can trick the code by using special character sequences
    • Make use of tcpdump, to check the whether or not mysql data streams r unencrypted:
    • tcpdump –l –i eth0 –w – src port 3306|strings
    • Dont run mysqld as root.
    • Don’t give process and file privileges to users as far as possible.
  • 13. Continued…..
    • Following mysqld options affect security: 1. –- secure 2. – skip-grant-privileges 3. – skip-name-resolve 4. –skip-networking
    • Passwords by default are stored in hashed form in database.But if the scrambled password is known the hacker can still log in as the user.
    • Passwords can be stored in my.cnf file when non-interactive access has to be done
    • Inbuilt functions for hashing: password, encrypt,encode,decode
  • 14. Compatibility with Standards
    • What doesn’t MySQL have ?
    • Transactions – no provision for commit and rollback
    • No nested sub-queries
    • Views are not supported
    • Foreign keys not used for referential integrity checks
  • 15. Compatibility (contd.)
    • What extra does MySQL have ?
    • Locking/Unlocking of tables
    • Atomicity of operations
    • Directory organization
    • Access of tables across tables
    • Several other features, discussed later…
  • 16. More about Locks !
    • Locks help in maintaining integrity, atomicity
    • Read locks – enable you to only read from the locked tables.
    • Write locks – enable you to read and write exclusively. Other threads can’t access/update currently locked tables
    • Write locks have higher priority than read locks
  • 17. MySql Table Types
    • Creates a .frm file that holds the table and column definition.
    • Syntax for defining table type is .. : CREATE TABLE test ( ) TYPE=HEAP ..
    • Categorization of types : Transaction safe type and Non transaction safe type.
    • Transaction Safe table types allow rollbacks,restore changes if update fails ,etc .
    • Non Transaction Safe table types are much faster ,use less disk space as well as memory for updates.
  • 18. MyISAM tables
    • Use B-Tree indexing to store the keys, string indexes are compressed .
    • MyISAM itself supports three different table formats: a) static (fixed length) b) Dynamic c) Compressed
    • Static : fastest ,secure and simplest format , used when there are no varchar, blob or text.
    • Dynamic : each record stores a header that contain its length
    • Compressed : created using myisampack tool , they are read only ,use very little space as each record is compressed separately
    • ISAM is a deprecated version of MyISAM
  • 19. Merge tables
    • A collection of identical MyISAM tables which are used collectively.
    • FOR eg :
    • CREATE TABLE t1 (a INT AUTO_INCREMENT PRIMARY KEY, message CHAR(20));
    • CREATE TABLE t2 (a INT AUTO_INCREMENT PRIMARY KEY, message CHAR(20)) ;
    • CREATE TABLE total (a INT NOT NULL, message CHAR(20), KEY(a)) TYPE=MERGE UNION=(t1,t2)
    • allowed : select ,insert and Operations update .
  • 20. Heap tables and Berkley DB
    • Use hashed index and are stored in memory
    • Generally used for temporary tables .
    • Berkley DB is used for making the tables transaction safe
  • 21. MySQL Language Reference
    • OPTIMIZE
    • Syntax :: … OPTIMIZE TABLE tbl_name[,tbl_name]..
    • Used only for MyISAM tables
    • It performs the following functions :repairs the table if the table has deleted rows,sorts the index,and the statistics are also made to date.
    • CHECK
    • Syntax :: … CHECK TABLE tbl_name[,tbl_name...] [TYPE = [QUICK | FAST | EXTEND | CHANGED]]
  • 22. MySQL Language Reference
    • Checks a table for errors and updates the key statistics of the table
    • BACKUP
    • BACKUP TABLE tbl_name[,tbl_name...] TO '/path/to/backup/directory‘
    • This again works only for MyISAM
    • ANALYZE
    • During analysis the table is locked with a read lock
  • 23. MySQL Language Reference
    • REPAIR
    • Syntax:
    • REPAIR TABLE tbl_name[,tbl_name...] [TYPE = QUICK]
    • FLUSH
    • Syntax :
    • FLUSH flush_option [,flush_option]
    • Used to clear the internal cache of Mysql
    • It has various options like HOSTS,LOGS,PRIVELEDGES, TABLES tbl_names,etc
  • 24. Replication in MySQL
    • What??
    • One server is designated as the master, while the other ( or others) as slave(s)
    • Updates done only on master and binary logs made
    • The slave connects to the master, catches up on the missed updates, and then starts receiving updates immediately as they come to the master.
    • Why??
    • For robustness you have two systems and switch to the backup if you have problems with the master.
    • The extra speed is achieved by sending a part of the non-updating queries to the replica server.
  • 25. How To (SLAVE)
    • Upgrade both slave and master to 3.23.15 or higher.
    • PUT THESE IN my.cnf of SLAVE
    • master-host,user,passwd
    • server-id=< unique no>= 1 & <=2^32-1
    • master-connect-retry !! (keep trying)
    • master-info-file
    • replicate-rewrite-db
    • skip-slave-start
    • Restart the slave(s)
  • 26. How To (SLAVE) (contd)
    • Take a snapshot of all the tables/databases on the master
    • Use command LOAD TABLE <tblname> FROM MASTER (3.23.23)+
    • SLAVE START/STOP
    • FLUSH SLAVE
  • 27. HOW TO (MASTER)
    • log-bin , FLUSH MASTER , FLUSH SLAVE
    • When you start the slave thread will be created
    • Tables are not Locked
    • SET SQL_LOG_BIN=0/1
    • CHANGE MASTER TO master_def_list