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[DMDB] Notes on concurrency control

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janishutz
2026-07-26 12:49:35 +02:00
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semester4/dmdb/parts/05_concurrency-control-recovery/03_concurrency-control.tex
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\newpage
\subsection{Concurrency Control}
\subsection{Concurrency Control (CC)}
The goal of concurrency control is to ensure the correct executions of concurrent transactions.
The baseline for correctness is, as previously mentioned, serial execution.
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\item Conflicting operations of non-aborted transactions are ordered in the same way in both histories
\end{enumerate}
\inlinedefinition[Serializable History] A history is serializable if and only it is equivalent to a serial history.
\inlinedefinition[(Conflict) Serializable History] A history is serializable if and only it is equivalent to a serial history.
A very simple way to check this is that a history is not CS if there are conflicting operations.
\inlinetheorem[Serializability] A history is serializable if and only if its serializability graph is acyclic.
The seerializabililty graph is constructed from the history graph as follows: