11aORMs

Database Management

Mick McQuaid
mcq@utexas.edu

University of Texas at Austin

10 May 2026

ORMs

  • A small but vocal subset of programmers urge people to abandon SQL access to relational databases in favor of ORMs (object-relational mappings)
  • I try to ignore them but you may encounter them as an alternative to SQL, so I must mention them
  • Their rationale seems to be that we think in terms of objects and processes
  • Also that the programs that access databases are written as object-oriented systems, so why not continue that abstraction into how we work with non object-oriented data in relational databases?

The object-relational impedance mismatch

  • Various academic papers describe this, such as Ireland et al. (2009) and Lorenz et al. (2017)
  • It’s a pretty advanced topic, requiring both knowledge of relational database systems beyond what we do in this course, and knowledge of object-oriented systems and the philosophies behind both of these systems
  • If I can put it simply, it is to say that the two systems represent different and sometimes conflicting world views and mapping from one to the other requires at least a complete programming language
  • On the other hand, ORMs are not complete languages but rather domain-specific languages with limited expressivity
  • Even papers rejecting SQL, such as Darwen and Date (1995), also reject ORMs

END

References

Darwen, Hugh, and C. J. Date. 1995. “The Third Manifesto.” SIGMOD Rec. (New York, NY, USA) 24 (1): 39–49. https://doi.org/10.1145/202660.202667.
Ireland, Christopher, David Bowers, Mike Newton, and Kevin Waugh. 2009. “A Classification of Object-Relational Impedance Mismatch.” First International Conference on Advances in Databases, Knowledge, and Data Applications (DBKDA). https://oro.open.ac.uk/18644/.
Lorenz, Martin, Jan-Peer Rudolph, Guenter Hesse, Matthias Uflacker, and Hasso Plattner. 2017. “Object-Relational Mapping Revisited - a Quantitative Study on the Impact of Database Technology on o/r Mapping Strategies.” Hawaii International Conference on System Sciences. https://api.semanticscholar.org/CorpusID:1323866.

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