deletions | additions       diff --git a/section_Query_Optimization_and_Execution__.tex b/section_Query_Optimization_and_Execution__.tex  index 2b7d2ed..edbeda4 100644  --- a/section_Query_Optimization_and_Execution__.tex  +++ b/section_Query_Optimization_and_Execution__.tex 
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\subsection{Join Query Execution Plans}  Consider query   SELECT \textbf{SELECT  * FROM A \\  JOIN \\}  \textbf{JOIN  B ON A.ID = B.ID \\  JOIN \\}  \textbf{JOIN  C ON A.ID = C.ID \\  JOIN \\}  \textbf{JOIN  D ON A.ID = D.ID \\ \\}    Two possible execution plans are deep-left tree (shown in Figure-1 ) and Bushy Tree (shown in Figure-2). Other possible structures include right-deep trees zig-zag trees. Similar to deep-left trees right-deep and zig-zag are linear tree structure. But bushy trees are different and more complicated compared to others.