Object Relational Mapping with Dapper (Micro ORM)
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The document discusses Object-Relational Mapping (ORM) with a focus on Dapper, a micro ORM for .NET, highlighting its architecture, advantages, and limitations. It compares traditional RDBMS with NoSQL and object-oriented databases, addressing issues like impedance mismatch and the need for ORM to bridge different type systems. Dapper is presented as a lightweight solution that prioritizes performance and simplicity, making it suitable for developers seeking efficient database interaction.
Object Relational Mapping with Dapper (Micro ORM)
- 2. Today's Topic Object Relational Mapping with Dapper (a micro ORM)
- 6. Types of Databases ● Relational Database Management Systems (RDBMS) ● NoSQL and Object-Oriented (OODBMS)
- 7. RDBMS Data Storage – Rows and columns (Tabular Form) Features – Simple, better performance of managing data – Mathematical foundation (Relational Algebra) – Flattening and scattering -> unnatural – Limitations: everything doesn't fit in relations – Conversion needed (impedance mismatch)
- 8. NoSQL and OODBMS Data Storage – Object Form Features – No conversion needed (no impedance mismatch) – Relationships are directly represented, rather than requiring join tables/operations – Better at modeling complex objects – No mathematical foundation – Don’t have maturity of RDBMS yet
- 9. Incompatible Type Systems ● During systems collaboration if systems found having different type systems, they are said to be Incompatible Type Systems and can't interact with each other without an interface. E.g. OO Applications and RDBMS. ● A mechanism/solution is needed to overcome this incompatibility gap for proper collaboration.
- 11. What is an ORM? ● It is a programming technique for converting data between incompatible type systems in object-oriented programming languages.
- 12. Why to use ORM? ● Many popular database products such as structured query language database management systems (SQL DBMS) can only store and manipulate scalar values such as integers and strings organized within tables. The programmer must convert the object values for storage in the database into groups of simpler values (and convert them back upon retrieval). ● For most of the data-access code that developers usually need to write, it eliminates.
- 13. Problems with ORM ● Object-Relational Impedance Mismatch (paradigm mismatch) is a way of saying that object models and relational models do not work very well together. Loading and storing graphs of objects using a tabular relational database exposes 5 mismatch problems. – Granularity – Subtypes (inheritance) – Identity – Associations – Data navigation
- 14. Types of ORM ● Entity-based relational mapping – Change tracking, Lazy-loading, Eager fetching, Cascades, Identity map, Unit of work tracking ● Result-set-based relational mapping – Map straight to DTOs and skip needing to configure mapping ● DML-based relational mapping (micro ORMs) – SQL is brought to the forefront, mapping on the fly and only need a connection ● Bulk loading tools – Limited to INSERT and SELECT
- 15. Boring???
- 17. Why Dapper ? ● Simple object mapper for .Net ● Performance is a key feature
- 18. Why Dapper is Simple/ Lightweight? ● Many feature that ORMs ship with are stripped out, there is no identity map, there are no helpers for update/select and so on. ● Dapper does not manage your connection's life cycle, it assumes the connection it gets is open AND has no existing data readers enumerating.
- 20. Dapper in Action
- 21. Dapper in Action ● Dapper is a “single file” (SqlMapper.cs) that will extend your IDbConnection interface. ● It provides 3 helpers: – Execute a query and map the results to a strongly typed List – Execute a query and map it to a list of dynamic objects – Execute a Command that returns no results
- 22. (1) Query with Strongly Typed Result
- 23. (2) Query with Dynamic Object Result
- 24. (3) Command with No Result
- 25. Execute a Command multiple times
- 26. Execute a Stored Procedure
- 27. Multiple Results in Single Query
- 28. Limitations of Dapper? ● Many feature that ORMs ship with are stripped out, there is no identity map, there are no helpers for update/select and so on. ● Dapper does not manage your connection's life cycle, it assumes the connection it gets is open.
- 29. Final words on Dapper (Finally towards ending!)
- 30. Configurations (Most hectic activity)? Surprisingly!!! No configuration needed in project, just add reference to the library and you are done. – Reasons ● It uses existing db connection (extends IDbConnection). ● It just does object mapping, nothing else as mentioned in features.
- 31. Applications ● Stack Overflow ● Helpdesk ● And many more
- 32. Dapper and DB providers ● Dapper has no DB specific implementation details, it works across all .Net ADO providers including sqlite, sqlce, firebird, oracle, MySQL, PostgreSQL and SQL Server.
- 33. Conclusion ● Simple and lightweight to implement / use. ● Provide enough helpers/ support to do ORM activities. ● Doesn't suppress developers SQL skills.
- 34. Recommendation (Hybrid Approach) ● Dapper was written with speed (not features) as a priority. ● Using Dapper felt like writing SQL, which majority of developers avoid when possible. ● For Entity Framework slowness issue, replace queries with either a view or a stored procedure, depending on the situation. ● Hybrid approach: Use EF for normal cases due to ease and use Dapper where performance boost in needed.
- 35. References ● http://en.wikipedia.org/wiki/Object-relational_mapping ● http://hibernate.org/orm/what-is-an-orm/ ● https://github.com/StackExchange/dapper-dot-net ● https://www.cl.cam.ac.uk/~fms27/db/tr-98-2.pdf ● http://searchcio.techtarget.com/opinion/Relational-databases-are-far-from-dead-just-ask-Facebook ● https://www.quora.com/What-is-LinkedIn-s-database-architecture-like ● http://www.infoq.com/news/2010/08/linkedin-data-infrastructure ● http://blog.dontpaniclabs.com/post/2014/05/01/Speed-Comparison-Dapper-vs-Entity-Framework ● http://lostechies.com/jimmybogard/2012/07/20/choosing-an-orm-strategy/ ● http://forums.asp.net/t/1792276.aspx?which+is+better+to+use+dapper+or+entity