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GDB-4: Aufgabe 3 und 4 bearbeitet.

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Jim Martens
2013-12-07 12:01:42 +01:00
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gdb/G62B4_Dittrich-Lindemann-Martens.tex
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@ -120,4 +120,81 @@
DROP TABLE Rennstall;
\end{verbatim}
\end{itemize}
\section{SQL - Anfragen}
\subsection{} %a
\begin{verbatim}
SELECT DISTINCT obst.Sorte
FROM Person pers,
Allergie aller,
Obst obst
WHERE pers.PNR = aller.Person
AND aller.Obst = obst.ONR
AND pers.Vorname = 'Peter'
AND pers.Nachname = 'Meyer'
ORDER BY obst.Sorte DESC;
\end{verbatim}
\subsection{} %b
\begin{verbatim}
SELECT pers.PNR, pers.Nachname, COUNT(aller.Obst)
FROM Person pers,
Allergie aller
WHERE pers.PNR = aller.Person
GROUP BY pers.PNR;
\end{verbatim}
\subsection{} %c
\begin{verbatim}
SELECT pers.PNR
FROM Person pers,
Obst obst
WHERE pers.PNR = obst.Entdecker
GROUP BY pers.PNR
HAVING COUNT(obst.ONR) > 6;
\end{verbatim}
\subsection{} %d
\begin{verbatim}
SELECT pers.Vorname, pers.Nachname
FROM Person pers,
Person entdecker,
Obst obst
WHERE entdecker.PNR = obst.Entdecker
AND pers.Lieblingsobst = obst.ONR
AND entdecker.Vorname = pers.Vorname;
\end{verbatim}
\subsection{} %e
\begin{verbatim}
SELECT pers.PNR, pers.Vorname, pers.Nachname
FROM Person pers
WHERE pers.PNR NOT IN (SELECT obst.Entdecker
FROM Obst obst);
\end{verbatim}
\section{Optimierung}
anfänglicher Operatorbaum:\\
\begin{tikzpicture}[shorten >=1pt,node distance=1.1cm,on grid]
\node (proj) {$\pi_{Person.PNR, Person.Vorname, Person.Nachname}$};
\node (sel) [below=2.0 of proj] {$\sigma_{Obst.Sorte\text{ LIKE 'K\%'}}$};
\node (join) [below=2.0 of sel] {$\underset{Person.Lieblingsobst = Obst.ONR}{\bowtie}$};
\node (person) [below left=2.0 and 2.0 of join] {Person};
\node (obst) [below right=2.0 and 2.0 of join] {Obst};
\path (proj) edge node [right] {400} (sel)
(sel) edge node [right] {2000} (join)
(join) edge node [left] {2000} (person)
(join) edge node [right] {25} (obst);
\end{tikzpicture}
optimierter Operatorbaum:\\
\begin{tikzpicture}[shorten >=1pt,node distance=1.1cm,on grid]
\node (proj) {$\pi_{Person.PNR, Person.Vorname, Person.Nachname}$};
\node (join) [below=2.0 of proj] {$\underset{Person.Lieblingsobst = Obst.ONR}{\bowtie}$};
\node (person) [below left=2.0 and 2.0 of join] {Person};
\node (sel) [below right=2.0 and 2.0 of join] {$\sigma_{Obst.Sorte\text{ LIKE 'K\%'}}$};
\node (obst) [below=of sel] {Obst};
\path (proj) edge node [right] {400} (join)
(join) edge node [left] {2000} (person)
(join) edge node [right] {5} (sel)
(sel) edge node [right] {25} (obst);
\end{tikzpicture}
Der zweite Operatorbaum ist klar performanter, da die Selektion der Obstsorte bereits vor dem Join stattfindet.
\end{document}