update

src/tools/backend/index.html

@@ -43,8 +43,10 @@ Certain queries, like <I>SELECT,</I> return columns of data.  Other
 queries, like <I>INSERT</I> and <I>UPDATE,</I> specify the columns
 modified by the query.  These column references are converted to <A
 HREF="../../include/nodes/primnodes.h">Resdom</A> entries, which are
-linked together to make up the <I>target list</I> of the query. The
-target list is stored in Query.targetList, which is generated by
+placed in <A HREF="../../include/nodes/parsenodes.h">target list
+entries,</I> and linked together to make up the <I>target list</I> of
+the query. The target list is stored in Query.targetList, which is
+generated by
 <A HREF="../../backend/parser/parse_target.c">transformTargetList().</A>
 <P>
 Other query elements, like aggregates(<I>SUM()</I>), <I>GROUP BY,</I>
@@ -62,9 +64,13 @@ HREF="../../backend/optimizer/path">path</A> module determines the best
 table join order and join type of each table in the RangeTable, using
 Query.qual(<I>WHERE</I> clause) to consider optimal index usage.
 <P>
+
 The Plan is then passed to the <A
 HREF="../../backend/executor">executor</A> for execution, and the result
-returned to the client.
+returned to the client.  The Plan actually as set of nodes, arranged in
+a tree structure with a top-level node, and various sub-nodes as
+children.
+
 <P>
 There are many other modules that support this basic functionality.
 They can be accessed by clicking on the flowchart.