CRIMEWATCH CONSULTING FIRM

Presentation 2: Data Warehouse Design Discussion

Adwait Mulye, Yuga Pawar, Floyd J. Srubar, Vidyasagar Velamala

Brief Review of Business Needs “Value You’ll See Consulting” provides

decision support services to clientele from various industries.City of Houston – Staffing and

Resource PlanningRealtors – Neighborhood Crime

StatisticsSchool Districts – Land PurchasesBusiness Owners – Location Decisions

Brief Review of Business Needs Additionally, the use of a data warehouse

allows our firm to compile and re-assemble raw publicly available crime data into specific decision supporting material tailored to our clients’ information needs.

Tonight’s Discussion Overview Tonight’s discussions will address the

structure of the Data Warehousing system for our consulting firm.Database & Table Structure Discussion

○ Facts HPD Crime Data: June 01 – December 31, 2009

○ Dimensions [Date, Type of Crime, Police Beat, Premises]

Dimensional Modeling Discussion○ Star Schema○ Snowflake: Dimensional Hierarchies

Database and Table Structures

Database & Table Structure Takeaways

The fact table is publicly available data from the City of Houston website.

Dimensional tables are a joint effort by both the City of Houston and our consulting firm.

City of Houston data revealed natural dimensions based on hierarchies found in the HPD organizational chart.

Future Dimensions in the works:○ DimTimeOfDay: Morning, Mid-Day, Evening, Overnight○ DimSceneOfCrime: Based on Premises node, we see a pattern

emerging in that table for rolling up, or drilling down. Part of the “Data Cleansing Process” involved simple

tasks such as changing field names, and removing five orphaned records.

Fact Table: HPD Crime Data Jun – Dec 2009

*The data originates from the Houston Police Department’s OLTP systems.

Fact Table: HPD Crime Data Jun – Dec 2009

*The data originates from the Houston Police Department’s OLTP systems.

Dimension Table: Police Beats

Dimension Table: Police Beats

Dimension Table: DimOffenseTypes

Dimension Table: DimOffenseTypes

Dimension Table: DimDates

Dimension Table: DimDates

Dimension Table: DimPremisesCodes

Dimension Table: DimPremisesCodes

Dimensional Modeling

Snowflake Schema

Snowflake Schema

Dimensional Hierarchies

Police Beat Hierarchy Structure is similar to the HPD

organizational chart.Divisions: Treat these as Police Station

Locations, as this trend emerges from the fact tables, and later discovered on the HPD website. (see map)

Districts: A Division can have authority over multiple Districts. (e.g. Airport Division covers Hobby and Bush Airport districts.

Police Beats: A District has jurisdictional authority over many police patrol beats.