mirror of
https://git.osgeo.org/gitea/postgis/postgis
synced 2024-10-23 16:42:35 +00:00
ac79694824
git-svn-id: http://svn.osgeo.org/postgis/trunk@14960 b70326c6-7e19-0410-871a-916f4a2858ee
700 lines
24 KiB
XML
700 lines
24 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<sect1 id="Miscellaneous_Functions">
|
|
<title>Miscellaneous Functions</title>
|
|
|
|
<refentry id="ST_Accum">
|
|
<refnamediv>
|
|
<refname>ST_Accum</refname>
|
|
|
|
<refpurpose>Aggregate. Constructs an array of geometries.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>geometry[] <function>ST_Accum</function></funcdef>
|
|
<paramdef><type>geometry set</type> <parameter>geomfield</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>Aggregate. Constructs an array of geometries.</para>
|
|
<para>Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.</para>
|
|
<para>&Z_support;</para>
|
|
<para>&curve_support;</para>
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting>SELECT (ST_Accum(the_geom)) As all_em, ST_AsText((ST_Accum(the_geom))[1]) As grabone,
|
|
(ST_Accum(the_geom))[2:4] as grab_rest
|
|
FROM (SELECT ST_MakePoint(a*CAST(random()*10 As integer), a*CAST(random()*10 As integer), a*CAST(random()*10 As integer)) As the_geom
|
|
FROM generate_series(1,4) a) As foo;
|
|
|
|
all_em|grabone | grab_rest
|
|
|
|
-------------------------------------------------------------------------------+
|
|
|
|
{0101000080000000000000144000000000000024400000000000001040:
|
|
0101000080000000000
|
|
00018400000000000002C400000000000003040:
|
|
0101000080000000000000354000000000000038400000000000001840:
|
|
010100008000000000000040400000000000003C400000000000003040} |
|
|
POINT(5 10) | {010100008000000000000018400000000000002C400000000000003040:
|
|
0101000080000000000000354000000000000038400000000000001840:
|
|
010100008000000000000040400000000000003C400000000000003040}
|
|
(1 row)
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para><xref linkend="ST_Collect" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="Box2D">
|
|
<refnamediv>
|
|
<refname>Box2D</refname>
|
|
|
|
<refpurpose>Returns a BOX2D representing the maximum extents of the geometry.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>box2d <function>Box2D</function></funcdef>
|
|
<paramdef><type>geometry </type> <parameter>geomA</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>Returns a BOX2D representing the maximum extents of the geometry.</para>
|
|
|
|
<para>Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.</para>
|
|
<para>&curve_support;</para>
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting>SELECT Box2D(ST_GeomFromText('LINESTRING(1 2, 3 4, 5 6)'));
|
|
box2d
|
|
---------
|
|
BOX(1 2,5 6)
|
|
|
|
SELECT Box2D(ST_GeomFromText('CIRCULARSTRING(220268 150415,220227 150505,220227 150406)'));
|
|
box2d
|
|
--------
|
|
BOX(220186.984375 150406,220288.25 150506.140625)
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para><xref linkend="Box3D" />, <xref linkend="ST_GeomFromText" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="Box3D">
|
|
<refnamediv>
|
|
<refname>Box3D</refname>
|
|
|
|
<refpurpose>Returns a BOX3D representing the maximum extents of the geometry.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>box3d <function>Box3D</function></funcdef>
|
|
<paramdef><type>geometry </type> <parameter>geomA</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>Returns a BOX3D representing the maximum extents of the geometry.</para>
|
|
<para>Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.</para>
|
|
<para>&curve_support;</para>
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
<para>&Z_support;</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting>SELECT Box3D(ST_GeomFromEWKT('LINESTRING(1 2 3, 3 4 5, 5 6 5)'));
|
|
Box3d
|
|
---------
|
|
BOX3D(1 2 3,5 6 5)
|
|
|
|
SELECT Box3D(ST_GeomFromEWKT('CIRCULARSTRING(220268 150415 1,220227 150505 1,220227 150406 1)'));
|
|
Box3d
|
|
--------
|
|
BOX3D(220227 150406 1,220268 150415 1)
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para><xref linkend="Box2D" />, <xref linkend="ST_GeomFromEWKT" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="ST_EstimatedExtent">
|
|
<refnamediv>
|
|
<refname>ST_EstimatedExtent</refname>
|
|
|
|
<refpurpose>Return the 'estimated' extent of the given spatial table.
|
|
The estimated is taken from the geometry column's statistics. The
|
|
current schema will be used if not specified.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>box2d <function>ST_EstimatedExtent</function></funcdef>
|
|
<paramdef><type>text </type> <parameter>schema_name</parameter></paramdef>
|
|
<paramdef><type>text </type> <parameter>table_name</parameter></paramdef>
|
|
<paramdef><type>text </type> <parameter>geocolumn_name</parameter></paramdef>
|
|
<paramdef><type>boolean </type> <parameter>parent_ony</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
|
|
<funcprototype>
|
|
<funcdef>box2d <function>ST_EstimatedExtent</function></funcdef>
|
|
<paramdef><type>text </type> <parameter>schema_name</parameter></paramdef>
|
|
<paramdef><type>text </type> <parameter>table_name</parameter></paramdef>
|
|
<paramdef><type>text </type> <parameter>geocolumn_name</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>box2d <function>ST_EstimatedExtent</function></funcdef>
|
|
<paramdef><type>text </type> <parameter>table_name</parameter></paramdef>
|
|
<paramdef><type>text </type> <parameter>geocolumn_name</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>Return the 'estimated' extent of the given spatial table.
|
|
The estimated is taken from the geometry column's statistics. The
|
|
current schema will be used if not specified. The default behavior
|
|
is to also use statistics collected from children tables (tables
|
|
with INHERITS) if available. If 'parent_ony' is set to TRUE, only
|
|
statistics for the given table are used and children tables are
|
|
ignored.
|
|
</para>
|
|
|
|
<para>For PostgreSQL>=8.0.0 statistics are gathered by VACUUM
|
|
ANALYZE and resulting extent will be about 95% of the real
|
|
one.</para>
|
|
|
|
<note>
|
|
<para>
|
|
In absence of statistics (empty table or no ANALYZE called) this function
|
|
returns NULL. Prior to version 1.5.4 an exception was thrown
|
|
instead.
|
|
</para>
|
|
</note>
|
|
|
|
|
|
<para>For PostgreSQL<8.0.0 statistics are gathered by
|
|
update_geometry_stats() and resulting extent will be exact.</para>
|
|
|
|
<para>Availability: 1.0.0</para>
|
|
<para>Changed: 2.1.0. Up to 2.0.x this was called ST_Estimated_Extent.</para>
|
|
|
|
<para>&curve_support;</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting>SELECT ST_EstimatedExtent('ny', 'edges', 'the_geom');
|
|
--result--
|
|
BOX(-8877653 4912316,-8010225.5 5589284)
|
|
|
|
SELECT ST_EstimatedExtent('feature_poly', 'the_geom');
|
|
--result--
|
|
BOX(-124.659652709961 24.6830825805664,-67.7798080444336 49.0012092590332)
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para><xref linkend="ST_Extent" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
<refentry id="ST_Expand">
|
|
<refnamediv>
|
|
<refname>ST_Expand</refname>
|
|
<refpurpose>Returns bounding box expanded in all directions from the bounding box of the input geometry. Uses double-precision</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>geometry <function>ST_Expand</function></funcdef>
|
|
<paramdef><type>geometry </type> <parameter>geom</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>units_to_expand</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>geometry <function>ST_Expand</function></funcdef>
|
|
<paramdef><type>geometry </type> <parameter>geom</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>dx</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>dy</parameter></paramdef>
|
|
<paramdef choice="opt"><type>float</type> <parameter>dz=0</parameter></paramdef>
|
|
<paramdef choice="opt"><type>float</type> <parameter>dm=0</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>box2d <function>ST_Expand</function></funcdef>
|
|
<paramdef><type>box2d </type> <parameter>box</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>units_to_expand</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>box2d <function>ST_Expand</function></funcdef>
|
|
<paramdef><type>box2d </type> <parameter>box</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>dx</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>dy</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>box3d <function>ST_Expand</function></funcdef>
|
|
<paramdef><type>box3d </type> <parameter>box</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>units_to_expand</parameter></paramdef>
|
|
</funcprototype>
|
|
|
|
<funcprototype>
|
|
<funcdef>box3d <function>ST_Expand</function></funcdef>
|
|
<paramdef><type>box3d </type> <parameter>box</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>dx</parameter></paramdef>
|
|
<paramdef><type>float</type> <parameter>dy</parameter></paramdef>
|
|
<paramdef choice="opt"><type>float</type> <parameter>dz=0</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>This function returns a bounding box expanded from the bounding box of the input,
|
|
either by specifying a single distance with which the box should be expanded in all
|
|
directions, or by specifying an expansion distance for each direction.
|
|
|
|
Uses double-precision. Can be very useful for distance queries, or to add a bounding box
|
|
filter to a query to take advantage of a spatial index.</para>
|
|
<para>In addition to the geometry version of ST_Expand, which is the most commonly used, variants
|
|
are provided that accept and produce internal BOX2D and BOX3D data types.
|
|
</para>
|
|
<para>ST_Expand is similar in concept to ST_Buffer, except while buffer expands the geometry in all directions,
|
|
ST_Expand expands the bounding box an x,y,z unit amount.</para>
|
|
<para>Units are in the units of the spatial reference system in use denoted by the SRID.</para>
|
|
|
|
<note>
|
|
<para>Pre 1.3, ST_Expand was used in conjunction with distance to do indexable queries. Something of the form
|
|
<code>the_geom && ST_Expand('POINT(10 20)', 10) AND ST_Distance(the_geom, 'POINT(10 20)') < 10</code>
|
|
Post 1.2, this was replaced with the easier ST_DWithin construct.</para>
|
|
</note>
|
|
|
|
<note>
|
|
<para>Availability: 1.5.0 behavior changed to output double precision instead of float4 coordinates.</para>
|
|
<para>Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.</para>
|
|
<para>Enhanced: 2.3.0 support was added to expand a box by different amounts in different dimensions.</para>
|
|
</note>
|
|
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
|
|
</refsection>
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
<note><para>Examples below use US National Atlas Equal Area (SRID=2163) which is a meter projection</para></note>
|
|
<programlisting>
|
|
<!-- TODO: fix results of documentation to reflect new behavior -->
|
|
--10 meter expanded box around bbox of a linestring
|
|
SELECT CAST(ST_Expand(ST_GeomFromText('LINESTRING(2312980 110676,2312923 110701,2312892 110714)', 2163),10) As box2d);
|
|
st_expand
|
|
------------------------------------
|
|
BOX(2312882 110666,2312990 110724)
|
|
|
|
--10 meter expanded 3d box of a 3d box
|
|
SELECT ST_Expand(CAST('BOX3D(778783 2951741 1,794875 2970042.61545891 10)' As box3d),10)
|
|
st_expand
|
|
-----------------------------------------------------
|
|
BOX3D(778773 2951731 -9,794885 2970052.61545891 20)
|
|
|
|
--10 meter geometry astext rep of a expand box around a point geometry
|
|
SELECT ST_AsEWKT(ST_Expand(ST_GeomFromEWKT('SRID=2163;POINT(2312980 110676)'),10));
|
|
st_asewkt
|
|
-------------------------------------------------------------------------------------------------
|
|
SRID=2163;POLYGON((2312970 110666,2312970 110686,2312990 110686,2312990 110666,2312970 110666))
|
|
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<refsection>
|
|
<title>See Also</title>
|
|
<para><xref linkend="ST_AsEWKT" />, <xref linkend="ST_Buffer" />, <xref linkend="ST_DWithin" />, <xref linkend="ST_GeomFromEWKT" />, <xref linkend="ST_GeomFromText" />, <xref linkend="ST_SRID" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="ST_Extent">
|
|
<refnamediv>
|
|
<refname>ST_Extent</refname>
|
|
<refpurpose>an aggregate function that returns the bounding box that bounds rows of geometries.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>box2d <function>ST_Extent</function></funcdef>
|
|
<paramdef><type>geometry set</type> <parameter>geomfield</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>ST_Extent returns a bounding box that encloses a set of geometries. The ST_Extent function is an "aggregate" function in the
|
|
terminology of SQL. That means that it operates on lists
|
|
of data, in the same way the SUM() and AVG() functions do.</para>
|
|
<para>Since it returns a bounding box, the spatial Units are in the units of the spatial reference system in use denoted by the SRID</para>
|
|
<para>ST_Extent is similar in concept to Oracle Spatial/Locator's SDO_AGGR_MBR</para>
|
|
<note>
|
|
<para>Since ST_Extent returns a bounding box, the SRID meta-data is lost. Use ST_SetSRID to force it back into
|
|
a geometry with SRID meta data. The coordinates are in the units of the spatial ref of the orginal geometries.</para>
|
|
</note>
|
|
|
|
<note>
|
|
<para>ST_Extent will return boxes with only an x and y component even with (x,y,z) coordinate geometries. To maintain x,y,z use ST_3DExtent instead.</para>
|
|
</note>
|
|
|
|
<note>
|
|
<para>Availability: 1.4.0</para>
|
|
</note>
|
|
|
|
<para>Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.</para>
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
|
|
</refsection>
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
<note><para>Examples below use Massachusetts State Plane ft (SRID=2249)</para></note>
|
|
<programlisting>
|
|
|
|
SELECT ST_Extent(the_geom) as bextent FROM sometable;
|
|
st_bextent
|
|
------------------------------------
|
|
BOX(739651.875 2908247.25,794875.8125 2970042.75)
|
|
|
|
|
|
--Return extent of each category of geometries
|
|
SELECT ST_Extent(the_geom) as bextent
|
|
FROM sometable
|
|
GROUP BY category ORDER BY category;
|
|
|
|
bextent | name
|
|
----------------------------------------------------+----------------
|
|
BOX(778783.5625 2951741.25,794875.8125 2970042.75) | A
|
|
BOX(751315.8125 2919164.75,765202.6875 2935417.25) | B
|
|
BOX(739651.875 2917394.75,756688.375 2935866) | C
|
|
|
|
--Force back into a geometry
|
|
-- and render the extended text representation of that geometry
|
|
SELECT ST_SetSRID(ST_Extent(the_geom),2249) as bextent FROM sometable;
|
|
|
|
bextent
|
|
--------------------------------------------------------------------------------
|
|
SRID=2249;POLYGON((739651.875 2908247.25,739651.875 2970042.75,794875.8125 2970042.75,
|
|
794875.8125 2908247.25,739651.875 2908247.25))
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<refsection>
|
|
<title>See Also</title>
|
|
<para><xref linkend="ST_AsEWKT" />, <xref linkend="ST_3DExtent" />, <xref linkend="ST_SetSRID" />, <xref linkend="ST_SRID" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="ST_3DExtent">
|
|
<refnamediv>
|
|
<refname>ST_3DExtent</refname>
|
|
<refpurpose>an aggregate function that returns the box3D bounding box that bounds rows of geometries.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>box3d <function>ST_3DExtent</function></funcdef>
|
|
<paramdef><type>geometry set</type> <parameter>geomfield</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>ST_3DExtent returns a box3d (includes Z coordinate) bounding box that encloses a set of geometries. The ST_3DExtent function is an "aggregate" function in the
|
|
terminology of SQL. That means that it operates on lists
|
|
of data, in the same way the SUM() and AVG() functions do.</para>
|
|
<para>Since it returns a bounding box, the spatial Units are in the units of the spatial reference system in use denoted by the SRID</para>
|
|
|
|
<note>
|
|
<para>Since ST_3DExtent returns a bounding box, the SRID meta-data is lost. Use ST_SetSRID to force it back into
|
|
a geometry with SRID meta data. The coordinates are in the units of the spatial ref of the orginal geometries.</para>
|
|
</note>
|
|
|
|
<para>Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.</para>
|
|
<para>Changed: 2.0.0 In prior versions this used to be called ST_Extent3D</para>
|
|
<para>&Z_support;</para>
|
|
<para>&curve_support;</para>
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
</refsection>
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
<programlisting>
|
|
SELECT ST_3DExtent(foo.the_geom) As b3extent
|
|
FROM (SELECT ST_MakePoint(x,y,z) As the_geom
|
|
FROM generate_series(1,3) As x
|
|
CROSS JOIN generate_series(1,2) As y
|
|
CROSS JOIN generate_series(0,2) As Z) As foo;
|
|
b3extent
|
|
--------------------
|
|
BOX3D(1 1 0,3 2 2)
|
|
|
|
--Get the extent of various elevated circular strings
|
|
SELECT ST_3DExtent(foo.the_geom) As b3extent
|
|
FROM (SELECT ST_Translate(ST_Force_3DZ(ST_LineToCurve(ST_Buffer(ST_MakePoint(x,y),1))),0,0,z) As the_geom
|
|
FROM generate_series(1,3) As x
|
|
CROSS JOIN generate_series(1,2) As y
|
|
CROSS JOIN generate_series(0,2) As Z) As foo;
|
|
|
|
b3extent
|
|
--------------------
|
|
BOX3D(1 0 0,4 2 2)
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<refsection>
|
|
<title>See Also</title>
|
|
<para><xref linkend="ST_Extent" />, <xref linkend="ST_Force_3DZ" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
|
|
<refentry id="Find_SRID">
|
|
<refnamediv>
|
|
<refname>Find_SRID</refname>
|
|
|
|
<refpurpose>The syntax is find_srid(a_db_schema, a_table,
|
|
a_column) and the function returns the integer SRID of the
|
|
specified column by searching through the GEOMETRY_COLUMNS table.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>integer <function>Find_SRID</function></funcdef>
|
|
<paramdef><type>varchar </type> <parameter>a_schema_name</parameter></paramdef>
|
|
<paramdef><type>varchar </type> <parameter>a_table_name</parameter></paramdef>
|
|
<paramdef><type>varchar </type> <parameter>a_geomfield_name</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>The syntax is find_srid(<db/schema>, <table>,
|
|
<column>) and the function returns the integer SRID of the
|
|
specified column by searching through the GEOMETRY_COLUMNS table.
|
|
If the geometry column has not been properly added with the
|
|
AddGeometryColumns() function, this function will not work
|
|
either.</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting> SELECT Find_SRID('public', 'tiger_us_state_2007', 'the_geom_4269');
|
|
find_srid
|
|
----------
|
|
4269
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para><xref linkend="ST_SRID" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="ST_MemSize">
|
|
<refnamediv>
|
|
<refname>ST_MemSize</refname>
|
|
|
|
<refpurpose>Returns the amount of space (in bytes) the geometry takes.</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>integer <function>ST_MemSize</function></funcdef>
|
|
<paramdef><type>geometry </type> <parameter>geomA</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>Returns the amount of space (in bytes) the geometry takes. </para>
|
|
<para>This is a nice compliment to PostgreSQL built in functions pg_column_size, pg_size_pretty, pg_relation_size, pg_total_relation_size.</para>
|
|
<note><para>pg_relation_size which gives the byte size of a table may return byte size lower than ST_MemSize. This is because
|
|
pg_relation_size does not add toasted table contribution and large geometries are stored in TOAST tables.</para>
|
|
<para>pg_total_relation_size - includes, the table, the toasted tables, and the indexes.</para>
|
|
<para>pg_column_size returns how much space a geometry would take in a column considering compression, so may be lower than ST_MemSize</para>
|
|
</note>
|
|
|
|
<para>&Z_support;</para>
|
|
<para>&curve_support;</para>
|
|
<para>&P_support;</para>
|
|
<para>&T_support;</para>
|
|
<para>Changed: 2.2.0 name changed to ST_MemSize to follow naming convention. In prior versions this function was called ST_Mem_Size, old name deprecated though still available.</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting>
|
|
--Return how much byte space Boston takes up in our Mass data set
|
|
SELECT pg_size_pretty(SUM(ST_MemSize(the_geom))) as totgeomsum,
|
|
pg_size_pretty(SUM(CASE WHEN town = 'BOSTON' THEN ST_MemSize(the_geom) ELSE 0 END)) As bossum,
|
|
CAST(SUM(CASE WHEN town = 'BOSTON' THEN ST_MemSize(the_geom) ELSE 0 END)*1.00 /
|
|
SUM(ST_MemSize(the_geom))*100 As numeric(10,2)) As perbos
|
|
FROM towns;
|
|
|
|
totgeomsum bossum perbos
|
|
---------- ------ ------
|
|
1522 kB 30 kB 1.99
|
|
|
|
|
|
SELECT ST_MemSize(ST_GeomFromText('CIRCULARSTRING(220268 150415,220227 150505,220227 150406)'));
|
|
|
|
---
|
|
73
|
|
|
|
--What percentage of our table is taken up by just the geometry
|
|
SELECT pg_total_relation_size('public.neighborhoods') As fulltable_size, sum(ST_MemSize(the_geom)) As geomsize,
|
|
sum(ST_MemSize(the_geom))*1.00/pg_total_relation_size('public.neighborhoods')*100 As pergeom
|
|
FROM neighborhoods;
|
|
fulltable_size geomsize pergeom
|
|
------------------------------------------------
|
|
262144 96238 36.71188354492187500000
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
<refentry id="ST_Point_Inside_Circle">
|
|
<refnamediv>
|
|
<refname>ST_PointInsideCircle</refname>
|
|
|
|
<refpurpose>Is the point geometry insert circle defined by center_x, center_y, radius</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>boolean <function>ST_PointInsideCircle</function></funcdef>
|
|
<paramdef><type>geometry </type> <parameter>a_point</parameter></paramdef>
|
|
<paramdef><type>float </type> <parameter>center_x</parameter></paramdef>
|
|
<paramdef><type>float </type> <parameter>center_y</parameter></paramdef>
|
|
<paramdef><type>float </type> <parameter>radius</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsection>
|
|
<title>Description</title>
|
|
|
|
<para>The syntax for this functions is
|
|
ST_PointInsideCircle(<geometry>,<circle_center_x>,<circle_center_y>,<radius>).
|
|
Returns the true if the geometry is a point and is inside the
|
|
circle. Returns false otherwise.</para>
|
|
<note><para>This only works for points as the name suggests</para></note>
|
|
|
|
<para>Availability: 1.2</para>
|
|
<para>Changed: 2.2.0 In prior versions this used to be called ST_Point_Inside_Circle</para>
|
|
</refsection>
|
|
|
|
|
|
<refsection>
|
|
<title>Examples</title>
|
|
|
|
<programlisting>SELECT ST_PointInsideCircle(ST_Point(1,2), 0.5, 2, 3);
|
|
st_pointinsidecircle
|
|
------------------------
|
|
t
|
|
</programlisting>
|
|
</refsection>
|
|
|
|
<!-- Optionally add a "See Also" section -->
|
|
<refsection>
|
|
<title>See Also</title>
|
|
|
|
<para><xref linkend="ST_DWithin" /></para>
|
|
</refsection>
|
|
</refentry>
|
|
|
|
|
|
</sect1>
|