1. Conceptual Architecture of PostgreSQL
S-Queue-L
Khurrum A Mujeeb, Adam Abu Hijleh, Adam Ali
Stephen McDonald, Wisam Zaghal
CISC Fall 2010

2. Overview What is Postgres? Research Methods Considered Alternatives
Reference Architecture
Conceptual Architecture
Inside Subsystems – Query Processor
Inside Subsystems – Storage Manager
Inside Subsystems – Utilities
Use Case
Concurrency Control
Design Trade-offs
Limitations of Research
Lessons Learned
Summary
Q & A

3. What is PostgreSQL? Open-Source database management system
‘Ingres Project’ at UC Berkeley
First Postgres version released in 1997
Cross-Platform
Written in C
Used by organisations such as:-
Yahoo
MySpace
Skype

4. Research Methods General understanding of PostgreSQL
Developers guide
PostgreSQL  wiki page
PostgreSQL manual
Wikipedia
Reference architecture for Database Management System
Backbone of conceptual architecture
Conceptual architecture for PostgreSQL
Various available online documentation of Conceptual Architectures of PostgreSQL

5. Considered Alternatives
1. Client – Server 2. Client – Server w/ Pipe & Filter 3. Client – Server w/ Pipeline & Repository

6. Reference Architecture
Figure. 1

7. Conceptual Architecture
Client Communications Manager
Legend
Dependencies
Utilities &
Shared Components
Server
(Query Processor)
Storage
Manager
Figure 2.

8. Query Processor
Figure 3.

9. Inside Subsystems Query Processor
Consists of :-
Parser: syntax
Traffic Cop : simple/complex
Utility Command: simple queries
Rewriter: rule augmentation
Planner/Optimizer: optimal plan
Executor: execute optimal plan
Models a Pipe & Filter style Architecture
Uses storage management & shared utilities

10. Inside Subsystems Storage Manager
Legend
Provides Shared memory for buffers & access to database.
Suggests repository style
Figure 4.

11. Inside Subsystems Utilities
Legend
Consists of :
Utilities
Catalog
Access Methods
Nodes/Lists
Utilities are used by
all sub-components of
the query processor
Figure 5.

12. Use Case – Select Query
Figure 6.

13. Concurrency Control
Postmaster spawns multiple server threads (process per request)
Problem - overwriting or modifying data
Solution…
- MVCC – Multi-version concurrency control
- Point in time DB snapshot
- Locks – locks entire table from being altered/deleted

14. Design Trade-offs Reliability vs Performance
Scalability vs Maintainability
Security vs Performance

15. Limitations of Research
Personal Knowledge as well as experience with architectures & databases
Determining depth of research
Sources are incomplete

16. Lessons Learned
Cannot rely on one source for information, will have to go through several sources to build a complete picture
Hard to decide on an architecture style
The value of the reference architecture

17. Summary Hybrid Conceptual Architecture Design Attributes
Client Server – front/back connection
Pipe & Filter – back end processes
Repository – storage management/access
Design Attributes
Reliable & Secure
- data integrity, strict SQL compliance, user authentication
Performance
- slower and more complicated

18. Thank You!
Questions?