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-rw-r--r--doc/src/sgml/datatype.sgml20
1 files changed, 17 insertions, 3 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 2e637c36ebe..e6b975dfd0e 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -3264,7 +3264,7 @@ SELECT person.name, holidays.num_weeks FROM person, holidays
</row>
<row>
<entry><type>line</type></entry>
- <entry>32 bytes</entry>
+ <entry>24 bytes</entry>
<entry>Infinite line</entry>
<entry>{A,B,C}</entry>
</row>
@@ -3309,6 +3309,11 @@ SELECT person.name, holidays.num_weeks FROM person, holidays
</table>
<para>
+ In all these types, the individual coordinates are stored as
+ <type>double precision</type> (<type>float8</type>) numbers.
+ </para>
+
+ <para>
A rich set of functions and operators is available to perform various geometric
operations such as scaling, translation, rotation, and determining
intersections. They are explained in <xref linkend="functions-geometry"/>.
@@ -3497,8 +3502,17 @@ SELECT person.name, holidays.num_weeks FROM person, holidays
<para>
Polygons are represented by lists of points (the vertexes of the
- polygon). Polygons are very similar to closed paths, but are
- stored differently and have their own set of support routines.
+ polygon). Polygons are very similar to closed paths; the essential
+ semantic difference is that a polygon is considered to include the
+ area within it, while a path is not.
+ </para>
+
+ <para>
+ An important implementation difference between polygons and
+ paths is that the stored representation of a polygon includes its
+ smallest bounding box. This speeds up certain search operations,
+ although computing the bounding box adds overhead while constructing
+ new polygons.
</para>
<para>