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	\begin{Large}
		\quote{A curry can be written in many different ways}
	\end{Large}

	\hspace{3cm} - Prof. Dr. Gustavo Alonso, 2026
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	FS2026, ETHZ

	\begin{Large}
		Summary of the Lecture Slides
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	\url{https://systems.ethz.ch/education/courses/2026-spring/dmdb.html}
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\section{Introduction}
A note on the quote on the title page: He did not \textit{actually} mean ``curry'', but of course ``query'', but he just pronounced it that way.

This summary assumes some basic knowledge about databases.
All words written in \textbf{bold} should be clickable and should link you to the corresponding term in the glossary.
If I did not forget a term that is, of course.

\subsection{IMS}
Early databases were not relational and they also required the user of the system to know \textit{how the data was stored}.
This of course is not ideal, as any update to the data structure also required an update to the code interacting with it.
In addition, manual query optimization has to be done.

Non-relational databases commonly have data redundancy, due to non-hierarchical applications being forced into a tree-based model.
This causes issues when updating the data, as one needs to update the data in all places where a copy of the data exists.

\subsection{Network Model}
In a network model, one \gls{record} is fetched at a time, so it essentially traverses the network.
However, we again do not have data independence, thus the application again needs to change when the physical data representation changes.
In addition, manual query optimization has to happen again, thus, any change to the physical data representation may cause the need to redo the optimization.

\subsection{Relational Model}
\bi{This is the focus of this course}

The relational model has the benefit of having data independence: The application doesn't know how the data is stored and represented.
The queries stay the same, even if the data representation changes.
In addition, the end user does not have to worry about optimization too much. This, of course, only applies to a limited extent.

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