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Database ManagementSystems For Mobile

Devices

Robert L. Foster Jr.

November 18, 2008


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Light Weight DBMS?

Definition

Purpose Examples

Tradeoffs


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Formal Definition

There isnt one...

Major DBMSs can run on mostoperating systems providing fullfunctionality: MySQl Oracle etc...

What about embedded systems? Why do we need one?


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DBMS For Mobile Devices DBMSs for mobiledevice should be

dedicated to

optimizing at least

one of the

following,preferably both:

poweroptimization

memorymanagement

commonality: small


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Power Optimization

Mobile devices such as laptops, cellphones, PDAs, and radios have a limited

power supply.

How can we optimize our DBMS to use asfew resources as possible while providing

the necessary functionality?

What is the necessary functionality for amobile device?


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Power Optimization

Continued...

Query

Add Delete

Atomicity?


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Memory

Management How much memory is available on the

device at any given time?

How much of the devices internalmemory should be dedicated to the

DB?

How frequently can disk accesses bemade before latency issues arise?


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Examples There are

numerous light

weight DBMSs

dedicated toaddressing these

specific issues.

How do we choosewhich system isthe best for a given

device?


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Examples Whats good for the goose is notnecessarily whats good for the

gander...

Mobile phones have increasingly largeramounts of memory, and faster internetconnections.

Multi-Touch technology and GPScapabilities are a drain on batteries, andmemory.


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Metrics What should we consider when choosing a light

weight DBMS for a device?

Operating System

Acidity

Contents (Blobs, Clobs, etc...)

Max Sizes:

Database

Tables

Row Size

Columns Per Row

Views (caching)


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Metrics Continued...

Capabilities? Union Intersect

Inner Joins Outer Joins

Merge Language? Cost


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Options

SQLite

SmallSQL

Pyrrho DBMS ScimoreDB

HSQLDB Embedded MySQL


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HSQLDB Hyperthreaded Structured Query

Language

Written in Java Offers JDBC Driver 100-600k

Cross Platform OpenOffice & Mathematica


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ScimoreDB Embedded

Distributed Query Language (DQL)

Text based query language

Windows Only C++

ACID

Independent process or part of your application

Free

4MB (A relatively small footprint in comparison)


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SmallSQL

Java

JDBC Driver 200k No Installation Required

Provides no network interface or usermanagement...so whats it good for?


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SQLite ACID C

Cross Platform

500K

Uses a Single Database File

FREE!


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SQLite Continued...

Not a stand alone process A library?

Linked Function Calls Dynamically Typed (Read Weakly)

C, C++, Java, C#, and LISP bindingsavailable SQLite3


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More on SQLite SQLite3 - Stand alone application provides: create database

define tables insert and change rows run queries

manage database Single application (Resides on the host

machine)


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SQLite Code Samples Because of weak typing and the use of a single database file several

layers may be necessary.

SQLiteDatabaseCalls

#include "sqlite3.h"

/*Minimal SQLite3 Interface this provides the only access to SQLite3

library functions*/

sqlite3* createDatabase(char*pFilename);

int getDataFromDB(sqlite3* db, constchar* sqlCommand, char** &

data, int& rows, int & cols);

int clearOldData(sqlite3* db, constchar* sqlCommand);

int insertResults(sqlite3* db, int currentTime, constchar*

sqlCommand);

int clearEntries(sqlite3* db, constchar* sqlCommand);


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Code Samples Continued...

DatabaseManager#include "SQLDatabaseCalls.h"

//Basic Interface Provided to Client Code

void* DbHandleCreate();

int DbHandleClose(void* pHandle);

bool addDatatoTable(constchar* sqlCommand);

bool clearTable(const char* sqlCommand);

bool clearTableEntry(constchar* sqlCommand);char** queryEntry(constchar* sqlCommand, int & rows, int &

cols);

void freeTable(char** table);


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Code Samples Continued...

Client Code

# include "DbManager.h"

//Uses The DatabaseManager and handles all type issues and

structures

bool addPolicy(SPolicy* policy, SMode* oldMode, char* content);bool deletePolicy(constchar* modeID, constchar* policyID);

bool queryPolicy(int argc, char** argv, int & messagelen, char*&

xmlBuf);

bool deleteComplaint(int argc, char** argv);

bool deleteConflict(int argc, char** argv);

bool deleteMode(int argc, char** argv);

bool findComplaint(int argc, char** argv, int & messagelen, char*&

xmlBuf);

bool findConflict(int argc, char** argv, int & messagelen, char*&

xmlBuf);

bool findDecision(int argc, char** argv, int & messagelen, char*&

xmlBuf);


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SQLite IRL 125 million copies in Mozilla Firefox.

20 million Mac OS X computers, each of which contains multiplecopies of SQLite. (In Mac OS X v10.4 Apple introduced SQLite as a

persistence layer of the Core Data API.)

300 million downloads of Skype. (The Skype service has 100 millionregistered users.)

Nokia phones with Symbian OS version 9.4 or later. (The first one isNokia 5800)

Every iPhone and iPod touch.

Google Android phones like the T-Mobile G1


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Tradeoffs

Incomplete Functionality Support ACID compliance Boundary Limitations (Max Sizes)

Access Control Coding/Implementation overhead


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References Comparison of relational database management systems.

Wikipedia: The Free Encyclopedia. 15 November 2008

SQLite. Wikipedia: The Free Encyclopedia. 15 November 2008

HSQLDB. 15 November 2008

SmalSQL Database - the Java Desktop Database with JDBCinterface. 15 November 2008

Scimore - High performance distributed, client/server and fullyfeature embeded SQL database. 15 November 2008

SQLite Documentation. 15 November 2008
http://en.wikipedia.org/wiki/SQLitehttp://en.wikipedia.org/wiki/SQLitehttp://hsqldb.org/http://www.smallsql.de/http://www.smallsql.de/http://www.smallsql.de/http://www.smallsql.de/http://www.scimore.com/http://www.sqlite.org/docs.htmlhttp://www.sqlite.org/docs.htmlhttp://www.scimore.com/http://www.smallsql.de/http://www.smallsql.de/http://www.smallsql.de/http://www.smallsql.de/http://www.smallsql.de/http://www.smallsql.de/http://hsqldb.org/http://en.wikipedia.org/wiki/SQLitehttp://en.wikipedia.org/wiki/SQLite

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764 22 Foster DB4Mobile