Database Management System Choices

Introduction To Database Systems

CSE 373

Spring 2013

Outline

• Introduction

• PostgreSQL

• MySQL

• Microsoft SQL Server

• Choosing A DBMS

• NoSQL

Introduction

• There a lot of options for database management systems (DBMS)

• Popular choices include:• MySQL

• PostgreSQL

• Oracle

• Microsoft SQL Server

• IBM DB2

• Teradata

• Start by looking at PostgreSQL and continue on to some other popular choices

PostgreSQL

PostgreSQL

• Pronounced post-gres-q-l but often shortened to post-gres

• Free and open source• Free as in beer and free as in speech

• PostgreSQL is fully ACID compliant• Atomicity, Consistency, Isolation, Durability

• Uses SQL for querying• Most of the SQL : 2008 standard is implemented

• PostgreSQL is seen as more standard compliant than most choices

PostgreSQL

• PostgreSQL is generally viewed as a powerful database

• Why?• A lot of built-in data types such as Boolean, Circles, Lines, IPv4, IPv6 and more

• Less forcing data into a datatype such as Booleans into Integers or Characters

• Numerous built-in procedures• Including math operations, string operations, and cryptography

• Built-in support for full text searches

• Stronger querying on views

• Can use foreign data wrappers to allow external data sources to be treated as if they were internal to the database• Files, other databases, etc..

• Generally, a wide range of features

PostgreSQL

• A very big reason for PostgreSQL’s reputation for power is its language support

• PostgreSQL has built-in support for writing procedures with• C/C++

• PL/pgSQL – PostgreSQL specific language that is similar to Oracle’s PL/SQL

• Tcl

• Perl

• Python

• Non built-in support for a lot of other popular languages• Java

• PHP

• R

• Scheme

PostgreSQL

• PostgreSQL is technically an object-relational DBMS• So is Oracle

• In addition to the standard relational model there is also an object oriented model• Direct support for objects, classes, methods and inheritance

• The object oriented model allows custom datatypes

• Leads to some very nice simplifications such as the datatype of a column being an array or a dictionary

• Also supports table inheritance• Consider storing cities and the ability to find state capitals

PostgreSQL

• Using the language support and the object oriented features of PostgreSQL developers can write their own libraries

• These libraries allow reusable extensions to PostgreSQL’sfunctionality

• There are a lot of existing libraries that are publically available that extend PostgreSQL’s functionality to accomplish specific tasks• Referred to as Contrib modules

• Such as better cryptography, better administration, key/value store support, benchmarking and a lot more

PostgreSQL

• PostgreSQL also has very strong support for transactional DDL

• DDL(data definition language) are the commands that allow a developer to perform actions such as building the database schema or migrating data

• Transactional DDL allows you to roll back the database to a previous state in order to fix errors during schema changes or migrations

PostgreSQL

• This support for transactional DDL leads to another area where PostgreSQL is perceived to as excelling at, this area is better data integrity and consistency

• This perception is also aided by PostgreSQL’s strictness with constraints• Other database systems are not as strict

• E.g. Inserting 1000 into a 2 digit number field will round to 99 in some databases, PostgreSQL will throw an error

• E.g. In other databases, a non-null date field can accept a nonsense date such as 00/00/0000, again PostgreSQL will throw an error

MySQL

MySQL

• Pronounced as My-s-q-l

• MySQL is the most popular DBMS available

• Popularized through the use of the “LAMP” stack for web applications• Linux, Apache, MySQL, PHP

• MySQL is perceived as being as a less powerful database system with fewer features but easier to use and with better performance• Seen as unable to do as much as PostgreSQL or Oracle

• Supports SQL : 1999 with some extra extensions

• A relational DBMS, not an object-relational DBMS• No classes, no objects, no inheritance

MySQL

• One feature that sets MySQL apart in the area of performance is its support for changing the storage engine

• A database’s storage engine handles creation, storage, and retrieval of the tables and data in the database

• This ability to change the storage engine allows changes to how data is stored or retrieved in order to improve performance or other measures

• Some examples of the supported engines• MyIASM – The default engine,• InnoDB – ACID compliant and more of a focus on recoverability• Memory – Stores all data in RAM for very fast accesses• CSV – Stores data in CSV (comma separate value) files for portability and easy

exchange

MySQL

• MySQL has a reputation for having a number of “gotchas”• “Gotchas” are unexpected behavior for statements or features that are

present in other systems

• MySQL has pretty strong support for backwards compatibility but this can also cause gotchas to be preserved over time• E.g. enums can only contain character values but can be defined to hold

integers

• E.g. Cannot default a date column as the result of the NOW() function

• E.g. Dividing by zero doesn’t cause an error but returns a NULL

MySQL

• MySQL was originally released as open source and free• Free as in beer and free as in speech

• Oracle Corp. obtained the rights to MySQL in 2010 and this caused some controversy

• After version 2, Oracle changed the licensing for MySQL to a proprietary license

• Oracle has made several moves to monetize MySQL by requiring payment for some versions and some features

• In response, some developers forked MySQL and founded MariaDBwhich is designed to be a drop-in replacement for MySQL

Microsoft SQL Server

Microsoft SQL Server

• SQL Server is Microsoft’s DBMS

• Closed source and generally, pretty expensive (several thousand dollars)• Express edition is available for free to learn and experiment on but has a

limited license

• Relational (not object-relational) database but still has a wide range of features• Including built-in full text search, transactional DDL and a lot more

• Is more focused on competing with Oracle than MySQL and PostgreSQL• Focused on large businesses and large databases

• In my experience has some very nice tools

Choosing A DBMS

Choosing A DBMS

• Choosing a database has more to do more with non-core features• Core features are concerned with storage, retrieval, and other features you

immediately think of when thinking of a database

• Certain requirements such as the ability to retrieve previous versions of a table may drive you to choosing a specific DBMS over another due to a feature that eases fulfilling that requirement

• Your experience with and preferences for databases will also play a role in database choice

NoSQL

NoSQL

• NoSQL is a recent topic that has gotten a lot of attention

• Name comes from not all of these systems using SQL• Sometimes referenced as meaning Not Only SQL

• NoSQL databases are more lightweight that conventional RDMS

• The general focus of NoSQL systems are on improved scalability and availability at the cost of looser consistency

• Very popular for systems dealing with a lot of data

• Most NoSQL systems (but not all) do not deal with tables• Graph databases, databases that store documents and key-value stores

NoSQL

• Example of NoSQL systems include• BigTable – Table based system

• Developed and used by Google

• MongoDB – Stores JSON (Javascript Object Notation) like documents

• Used by Craigslist, foursquare, MTV and other

• Neo4j – Graph database

• Dynamo – Key/Value store system

• Developed and used by Amazon

• Redis – An in-memory, key/value store system

• Used by Blizzard, Stack Overflow, GitHub, flicker

Questions?