diff --git a/doc/src/sgml/arch-dev.sgml b/doc/src/sgml/arch-dev.sgml
index 9ffb8427bf0..fb8a8bde009 100644
--- a/doc/src/sgml/arch-dev.sgml
+++ b/doc/src/sgml/arch-dev.sgml
@@ -528,26 +528,36 @@
- The executor mechanism is used to evaluate all four basic SQL query types:
- SELECT, INSERT, UPDATE, and
- DELETE. For SELECT, the top-level executor
- code only needs to send each row returned by the query plan tree off
- to the client. For INSERT, each returned row is inserted
- into the target table specified for the INSERT. This is
- done in a special top-level plan node called ModifyTable.
- (A simple
- INSERT ... VALUES command creates a trivial plan tree
- consisting of a single Result node, which computes just one
- result row, and ModifyTable above it to perform the insertion.
- But INSERT ... SELECT can demand the full power
- of the executor mechanism.) For UPDATE, the planner arranges
- that each computed row includes all the updated column values, plus
- the TID (tuple ID, or row ID) of the original target row;
- this data is fed into a ModifyTable node, which uses the
- information to create a new updated row and mark the old row deleted.
- For DELETE, the only column that is actually returned by the
- plan is the TID, and the ModifyTable node simply uses the TID
- to visit each target row and mark it deleted.
+ The executor mechanism is used to evaluate all four basic SQL query
+ types: SELECT, INSERT,
+ UPDATE, and DELETE.
+ For SELECT, the top-level executor code
+ only needs to send each row returned by the query plan tree
+ off to the client. INSERT ... SELECT,
+ UPDATE, and DELETE
+ are effectively SELECTs under a special
+ top-level plan node called ModifyTable.
+
+
+
+ INSERT ... SELECT feeds the rows up
+ to ModifyTable for insertion. For
+ UPDATE, the planner arranges that each
+ computed row includes all the updated column values, plus the
+ TID (tuple ID, or row ID) of the original
+ target row; this data is fed up to the ModifyTable
+ node, which uses the information to create a new updated row and
+ mark the old row deleted. For DELETE, the only
+ column that is actually returned by the plan is the TID, and the
+ ModifyTable node simply uses the TID to visit each
+ target row and mark it deleted.
+
+
+
+ A simple INSERT ... VALUES command creates a
+ trivial plan tree consisting of a single Result
+ node, which computes just one result row, feeding that up
+ toModifyTable to perform the insertion.