This document discusses moving beyond relational databases for high performance web applications. It introduces Redis, a data structure store, as an alternative. Redis supports common data structures like lists, sets, and sorted sets. It also discusses scaling challenges for relational databases under heavy loads and how Redis offers solutions through its flexible data model and ability to handle a high volume of read and write operations through data replication and partitioning. PHP clients exist to interface with Redis for building high performance web apps.

1. Beyond relational database
Building high performance website using
Redis and PHP
Pham Cong Dinh Hanoi PHP Day 2009
Software Developer December 19, 2009
Vega Corporation

2. What I am talking about
• Relational database in our world
• High performance web apps: new challenges
• Redis: A data structure store
• Using some of Redis's PHP clients
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Go beyond relational database 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr

3. Relational database in our world
• Question
• How can we store our data?
• Answer
Part 1 • Relational database
• ACID is our love
• Atomicity - all parts of a transaction succeed or none of
then succeed. Integrity.
• Consistency - Nothing in your transaction will violate the
rules of the database. Integrity.
• Isolation - Each transaction operates independently of
every other transaction.
• Durability - Once the database says that data is
committed there is no opportunity for that to be undone.
Go beyond relational database

4. Relational database in our world
• Brewer's (CAP) Theorem
• C: Consistency - The client perceives that a set
of operations has occurred all at once.
• Strong consistency: ACID
• A: Availability - Every operation must terminate
in an intended response. Requests are to be
served even when there is a partition in the
cluster.
• P: Partition tolerance - Operations will
complete, even if individual components are
unavailable.
Go beyond relational database

5. Relational database in our world
• BASE: An ACID Alternative
• Basically Available
• Soft state
• Eventually consistent.
• Data partitioning and decision between
Consistency and Availability.
Go beyond relational database

6. Relational database in our world
• Relational database in high performance
environments
• Google
• Facebook
• Wikipedia
• Live Journal
• Yahoo
FAILED?
• … but most companies does not need
more than a single database server
• … but modern web apps today is facing a
real challenge
Go beyond relational database

7. High performance web apps: new
challenges
• Web server is bottleneck
Part 2
Go beyond relational database

8. High performance web apps: new
challenges
• Database is bottleneck
Go beyond relational database

9. High performance web apps: new
challenges
• CPU is bottleneck
Go beyond relational database

10. High performance web apps: new
challenges
• More requests: going distributed is easy
• Apache
• PHP
• Database scalability is hard
• Struggling with SMP: MySQL
• Replication is hard: replication is single
threaded: MySQL
• Most relational databases find hard to scale
WRITEs
• Schema constraints
• Disk I/O
• Memory constraints
• Global lock
• Complicated data types
Go beyond relational database

11. High performance web apps: new
challenges
• Scaling for READ is easier for scaling for
WRITE
mysql> select count(1) from setacc;
+----------+
| count(1) |
+----------+
| 3982438 |
+----------+
1 row in set (0.00 sec)
mysql> select count(1) from setacc_del;
+----------+
| count(1) |
+----------+
| 4003793 |
+----------+
1 row in set (0.00 sec)
Go beyond relational database

12. REDIS: A data structure datastore
• Redis (REmote DIctionary Server)
• Network interface to language dependent
client library: Python, Java, Ruby, Erlang,
Part 3 C# …
• Written in C
• Latest version: 1.1
Go beyond relational database

13. REDIS: A data structure datastore
• In a most basic form, it is a key – value
store: think Memcached
• Not memory only
• Not immediately durable
• Supports set of complicated data structure
• Can be found at
http://code.google.com/p/redis/
Go beyond relational database

14. REDIS: A data structure datastore
• Database concept
• SELECT index
Go beyond relational database

15. REDIS: A data structure datastore
• Key => Value
• SET mykey myvalue
• GET mykey
• More: MGET, MSET
•
Go beyond relational database

16. REDIS: A data structure datastore
• LIST
• RPUSH mylistkey string
• LPUSH mylistkey string
• LLEN mylistkey
• LPOP mylistkey
• RPOP mylistkey
• More: LGET/LSET ...
Go beyond relational database

17. REDIS: A data structure datastore
• SET
• SADD mysetkey member
• SREM key member
• Sorted SET
Go beyond relational database

18. Redis PHP clients
• Owlient's phpredis
• Can be found at
http://github.com/owlient/phpredis
Phần 4 • C extension
Go beyond relational database

19. Any question?
Phần 4
Go beyond relational database