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reference_raster.xml
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<?xml version="1.0" encoding="UTF-8"?>
<chapter id="RT_reference">
<title>Raster Reference</title>
<para>The functions given below are the ones which a user of PostGIS Raster is
likely to need and which are currently available in PostGIS Raster. There are other functions which are required support
functions to the raster objects which are not of use to a general
user.</para>
<para><varname>raster</varname> is a new PostGIS type for storing and analyzing raster data. </para>
<para>For loading rasters from raster files please refer to <xref linkend="RT_Loading_Rasters" /></para>
<para>For the examples in this reference we will be using a raster table of dummy rasters - Formed with the following code </para>
<programlisting language="sql">CREATE TABLE dummy_rast(rid integer, rast raster);
INSERT INTO dummy_rast(rid, rast)
VALUES (1,
('01' -- little endian (uint8 ndr)
||
'0000' -- version (uint16 0)
||
'0000' -- nBands (uint16 0)
||
'0000000000000040' -- scaleX (float64 2)
||
'0000000000000840' -- scaleY (float64 3)
||
'000000000000E03F' -- ipX (float64 0.5)
||
'000000000000E03F' -- ipY (float64 0.5)
||
'0000000000000000' -- skewX (float64 0)
||
'0000000000000000' -- skewY (float64 0)
||
'00000000' -- SRID (int32 0)
||
'0A00' -- width (uint16 10)
||
'1400' -- height (uint16 20)
)::raster
),
-- Raster: 5 x 5 pixels, 3 bands, PT_8BUI pixel type, NODATA = 0
(2, ('01000003009A9999999999A93F9A9999999999A9BF000000E02B274A' ||
'41000000007719564100000000000000000000000000000000FFFFFFFF050005000400FDFEFDFEFEFDFEFEFDF9FAFEF' ||
'EFCF9FBFDFEFEFDFCFAFEFEFE04004E627AADD16076B4F9FE6370A9F5FE59637AB0E54F58617087040046566487A1506CA2E3FA5A6CAFFBFE4D566DA4CB3E454C5665')::raster);</programlisting>
<sect1 id="Raster_Types">
<sect1info>
<abstract>
<para>This section lists the PostgreSQL data types specifically created to support raster functionality.</para>
</abstract>
</sect1info>
<title>Raster Support Data types</title>
<refentry id="geomval">
<refnamediv>
<refname>geomval</refname>
<refpurpose>A spatial datatype with two fields - geom (holding a geometry object)
and val (holding a double precision pixel value from a raster band).</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>geomval is a compound data type consisting of a geometry object referenced by the .geom field
and val, a double precision value that represents the pixel value at a particular geometric location in a raster band.
It is used by the ST_DumpAsPolygon and Raster intersection family of functions as an output type to explode a raster band into
geometry polygons.</para>
</refsection>
<refsection>
<title>See Also</title>
<para><xref linkend="PostGIS_Geometry_DumpFunctions" /> </para>
</refsection>
</refentry>
<refentry id="addbandarg">
<refnamediv>
<refname>addbandarg</refname>
<refpurpose>A composite type used as input into the ST_AddBand function defining the attributes and initial value of the new band.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A composite type used as input into the ST_AddBand function defining the attributes and initial value of the new band.
<variablelist>
<varlistentry>
<term>
<parameter>index </parameter>
<type>integer</type>
</term>
<listitem>
<para>
1-based value indicating the position where the new band will be added amongst the raster's bands. If NULL, the new band will be added at the end of the raster's bands.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>pixeltype </parameter>
<type>text</type>
</term>
<listitem>
<para>
Pixel type of the new band. One of defined pixel types as described in <xref linkend="RT_ST_BandPixelType" />.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>initialvalue </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
Initial value that all pixels of new band will be set to.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>nodataval </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
NODATA value of the new band. If NULL, the new band will not have a NODATA value assigned.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_ST_AddBand" />
</para>
</refsection>
</refentry>
<refentry id="rastbandarg">
<refnamediv>
<refname>rastbandarg</refname>
<refpurpose>A composite type for use when needing to express a raster and a band index of that raster.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A composite type for use when needing to express a raster and a band index of that raster.
<variablelist>
<varlistentry>
<term>
<parameter>rast </parameter>
<type>raster</type>
</term>
<listitem>
<para>
The raster in question/
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>nband </parameter>
<type>integer</type>
</term>
<listitem>
<para>
1-based value indicating the band of raster
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_ST_MapAlgebra" />
</para>
</refsection>
</refentry>
<refentry id="raster">
<refnamediv>
<refname>raster</refname>
<refpurpose>raster spatial data type.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>raster is a spatial data type used to represent raster data such as those imported from JPEGs, TIFFs, PNGs, digital elevation models.
Each raster has 1 or more bands each having a set of pixel values. Rasters can be georeferenced.</para>
<note>
<para>Requires PostGIS be compiled with GDAL support. Currently rasters can be implicitly converted to geometry type, but the conversion returns the
<xref linkend="RT_ST_ConvexHull" /> of the raster. This auto casting may be removed in the near future so don't rely on it.</para>
</note>
</refsection>
<refsection>
<title>Casting Behavior</title>
<para>This section lists the automatic as well as explicit casts allowed for this data type</para>
<informaltable rowsep="1" frame="all">
<tgroup cols="2">
<tbody>
<row>
<entry>Cast To</entry>
<entry>Behavior</entry>
</row>
<row>
<entry>geometry</entry>
<entry>automatic</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</refsection>
<refsection>
<title>See Also</title>
<para><xref linkend="RT_reference" /></para>
</refsection>
</refentry>
<refentry id="reclassarg">
<refnamediv>
<refname>reclassarg</refname>
<refpurpose>A composite type used as input into the ST_Reclass function defining the behavior of reclassification.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>A composite type used as input into the ST_Reclass function defining the behavior of reclassification.</para>
<variablelist>
<varlistentry>
<term><parameter>nband </parameter><type>integer</type></term>
<listitem><para>The band number of band to reclassify.</para></listitem>
</varlistentry>
<varlistentry>
<term><parameter>reclassexpr </parameter><type>text</type></term>
<listitem><para>range expression consisting of comma delimited range:map_range mappings. : to define mapping that defines how to map old band values to new band values. ( means >, ) means less than, ] < or equal, [ means > or equal</para>
<para><programlisting>1. [a-b] = a <= x <= b
2. (a-b] = a < x <= b
3. [a-b) = a <= x < b
4. (a-b) = a < x < b</programlisting></para>
<para>( notation is optional so a-b means the same as (a-b)</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>pixeltype </parameter><type>text</type></term>
<listitem><para>One of defined pixel types as described in <xref linkend="RT_ST_BandPixelType" /></para></listitem>
</varlistentry>
<varlistentry>
<term><parameter>nodataval </parameter><type>double precision</type></term>
<listitem><para>Value to treat as no data. For image outputs that support transparency, these will be blank.</para></listitem>
</varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Example: Reclassify band 2 as an 8BUI where 255 is nodata value</title>
<programlisting>SELECT ROW(2, '0-100:1-10, 101-500:11-150,501 - 10000: 151-254', '8BUI', 255)::reclassarg;</programlisting>
</refsection>
<refsection>
<title>Example: Reclassify band 1 as an 1BB and no nodata value defined</title>
<programlisting>SELECT ROW(1, '0-100]:0, (100-255:1', '1BB', NULL)::reclassarg;</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para><xref linkend="RT_ST_Reclass" /></para>
</refsection>
</refentry>
<refentry id="summarystats">
<refnamediv>
<refname>summarystats</refname>
<refpurpose>A composite type returned by the ST_SummaryStats and ST_SummaryStatsAgg functions.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A composite type returned by the <xref linkend="RT_ST_SummaryStats"/> and <xref linkend="RT_ST_SummaryStatsAgg"/> functions.
<variablelist>
<varlistentry>
<term>
<parameter>count </parameter>
<type>integer</type>
</term>
<listitem>
<para>
Number of pixels counted for the summary statistics.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>sum </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
Sum of all counted pixel values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>mean </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
Arithmetic mean of all counted pixel values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>stddev </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
Standard deviation of all counted pixel values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>min </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
Minimum value of counted pixel values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>max </parameter>
<type>double precision</type>
</term>
<listitem>
<para>
Maximum value of counted pixel values.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_ST_SummaryStats" />,
<xref linkend="RT_ST_SummaryStatsAgg" />
</para>
</refsection>
</refentry>
<refentry id="unionarg">
<refnamediv>
<refname>unionarg</refname>
<refpurpose>A composite type used as input into the ST_Union function defining the bands to be processed and behavior of the UNION operation.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A composite type used as input into the ST_Union function defining the bands to be processed and behavior of the UNION operation.
<variablelist>
<varlistentry>
<term>
<parameter>nband </parameter>
<type>integer</type>
</term>
<listitem>
<para>
1-based value indicating the band of each input raster to be processed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<parameter>uniontype </parameter>
<type>text</type>
</term>
<listitem>
<para>
Type of UNION operation. One of defined types as described in <xref linkend="RT_ST_Union" />.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_ST_Union" />
</para>
</refsection>
</refentry>
</sect1>
<sect1 id="Raster_Management_Functions">
<title>Raster Management</title>
<refentry id="RT_AddRasterConstraints">
<refnamediv>
<refname>AddRasterConstraints</refname>
<refpurpose>Adds raster constraints to a loaded raster table for a specific column that constrains spatial ref, scaling, blocksize, alignment, bands, band type and a flag to denote if raster column is regularly blocked. The table must be loaded with data for the constraints to be inferred. Returns true if the constraint setting was accomplished and issues a notice otherwise.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>boolean <function>AddRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>srid</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>scale_x</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>scale_y</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>blocksize_x</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>blocksize_y</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>same_alignment</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>regular_blocking</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>num_bands=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>pixel_types=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>nodata_values=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>out_db=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>extent=true</parameter>
</paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>AddRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef><type>text[] </type>
<parameter>VARIADIC constraints</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>AddRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rastschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef><type>text[] </type>
<parameter>VARIADIC constraints</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>AddRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rastschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>srid=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>scale_x=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>scale_y=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>blocksize_x=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>blocksize_y=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>same_alignment=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>regular_blocking=false</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>num_bands=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>pixel_types=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>nodata_values=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>out_db=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>extent=true</parameter>
</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>Generates constraints on a raster column that are used to display information in the <varname>raster_columns</varname> raster catalog.
The <varname>rastschema</varname> is the name of the table schema the table resides in. The <varname>srid</varname>
must be an integer value reference to an entry in the SPATIAL_REF_SYS
table.</para>
<para><varname>raster2pgsql</varname> loader uses this function to register raster tables</para>
<para>Valid constraint names to pass in: refer to <xref linkend="RT_Raster_Columns"/> for more details.</para>
<itemizedlist>
<listitem><para><varname>blocksize</varname> sets both X and Y blocksize</para></listitem>
<listitem><para><varname>blocksize_x</varname> sets X tile (width in pixels of each tile)</para></listitem>
<listitem><para><varname>blocksize_y</varname> sets Y tile (height in pixels of each tile)</para></listitem>
<listitem><para><varname>extent</varname> computes extent of whole table and applys constraint all rasters must be within that extent</para></listitem>
<listitem><para><varname>num_bands</varname> number of bands</para></listitem>
<listitem><para><varname>pixel_types</varname> reads array of pixel types for each band ensure all band n have same pixel type</para></listitem>
<listitem><para><varname>regular_blocking</varname> sets spatially unique (no two rasters can be spatially the same) and coverage tile (raster is aligned to a coverage) constraints</para></listitem>
<listitem><para><varname>same_alignment</varname> ensures they all have same alignment meaning any two tiles you compare will return true for. Refer to <xref linkend="RT_ST_SameAlignment" />.</para></listitem>
<listitem><para><varname>srid</varname> ensures all have same srid</para></listitem>
<listitem><para>More -- any listed as inputs into the above functions</para></listitem>
</itemizedlist>
<note>
<para>This function infers the constraints from the data already present in the table. As such for it to work, you must create the raster column first
and then load it with data.
</para>
</note>
<note>
<para>If you need to load more data in your tables after you have already applied constraints, you may want to run the DropRasterConstraints
if the extent of your data has changed.
</para>
</note>
<para>Availability: 2.0.0</para>
</refsection>
<refsection>
<title>Examples: Apply all possible constraints on column based on data</title>
<programlisting>CREATE TABLE myrasters(rid SERIAL primary key, rast raster);
INSERT INTO myrasters(rast)
SELECT ST_AddBand(ST_MakeEmptyRaster(1000, 1000, 0.3, -0.3, 2, 2, 0, 0,4326), 1, '8BSI'::text, -129, NULL);
SELECT AddRasterConstraints('myrasters'::name, 'rast'::name);
-- verify if registered correctly in the raster_columns view --
SELECT srid, scale_x, scale_y, blocksize_x, blocksize_y, num_bands, pixel_types, nodata_values
FROM raster_columns
WHERE r_table_name = 'myrasters';
srid | scale_x | scale_y | blocksize_x | blocksize_y | num_bands | pixel_types| nodata_values
------+---------+---------+-------------+-------------+-----------+-------------+---------------
4326 | 2 | 2 | 1000 | 1000 | 1 | {8BSI} | {0}
</programlisting>
</refsection>
<refsection>
<title>Examples: Apply single constraint</title>
<programlisting>CREATE TABLE public.myrasters2(rid SERIAL primary key, rast raster);
INSERT INTO myrasters2(rast)
SELECT ST_AddBand(ST_MakeEmptyRaster(1000, 1000, 0.3, -0.3, 2, 2, 0, 0,4326), 1, '8BSI'::text, -129, NULL);
SELECT AddRasterConstraints('public'::name, 'myrasters2'::name, 'rast'::name,'regular_blocking', 'blocksize');
-- get notice--
NOTICE: Adding regular blocking constraint
NOTICE: Adding blocksize-X constraint
NOTICE: Adding blocksize-Y constraint</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para><xref linkend="RT_Raster_Columns"/>, <xref linkend="RT_ST_AddBand"/>, <xref linkend="RT_ST_MakeEmptyRaster"/>, <xref linkend="RT_DropRasterConstraints"/>, <xref linkend="RT_ST_BandPixelType" />, <xref linkend="RT_ST_SRID" /></para>
</refsection>
</refentry>
<refentry id="RT_DropRasterConstraints">
<refnamediv>
<refname>DropRasterConstraints</refname>
<refpurpose>Drops PostGIS raster constraints that refer to a raster table column. Useful if you need to reload data or update your raster column data.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>boolean <function>DropRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>srid</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>scale_x</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>scale_y</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>blocksize_x</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>blocksize_y</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>same_alignment</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>regular_blocking</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>num_bands=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>pixel_types=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>nodata_values=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>out_db=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>extent=true</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>DropRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rastschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>srid=true</parameter></paramdef>
<paramdef><type>boolean </type>
<parameter>scale_x=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>scale_y=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>blocksize_x=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>blocksize_y=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>same_alignment=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>regular_blocking=false</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>num_bands=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>pixel_types=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>nodata_values=true</parameter></paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>out_db=true</parameter>
</paramdef>
<paramdef choice="opt"><type>boolean </type>
<parameter>extent=true</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>DropRasterConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>rastschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rasttable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>rastcolumn</parameter></paramdef>
<paramdef><type>text[] </type>
<parameter>constraints</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>Drops PostGIS raster constraints that refer to a raster table column that were added by <xref linkend="RT_AddRasterConstraints" />. Useful if you need to load more data or update your raster column data.
You do not need to do this if you want to get rid of a raster table or a raster column. </para>
<para>To drop a raster table use the standard <programlisting>DROP TABLE mytable</programlisting></para>
<para>To drop just a raster column and leave the rest of the table, use standard SQL <programlisting>ALTER TABLE mytable DROP COLUMN rast</programlisting></para>
<para>the table will disappear from the <varname>raster_columns</varname> catalog if the column or table is dropped. However if only the constraints are dropped, the
raster column will still be listed in the <varname>raster_columns</varname> catalog, but there will be no other information about it aside from the column name and table.</para>
<para>Availability: 2.0.0</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting>
SELECT DropRasterConstraints ('myrasters','rast');
----RESULT output ---
t
-- verify change in raster_columns --
SELECT srid, scale_x, scale_y, blocksize_x, blocksize_y, num_bands, pixel_types, nodata_values
FROM raster_columns
WHERE r_table_name = 'myrasters';
srid | scale_x | scale_y | blocksize_x | blocksize_y | num_bands | pixel_types| nodata_values
------+---------+---------+-------------+-------------+-----------+-------------+---------------
0 | | | | | | |
</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para><xref linkend="RT_AddRasterConstraints"/></para>
</refsection>
</refentry>
<refentry id="RT_AddOverviewConstraints">
<refnamediv>
<refname>AddOverviewConstraints</refname>
<refpurpose>Tag a raster column as being an overview of another.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>boolean <function>AddOverviewConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>ovschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>ovtable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>ovcolumn</parameter></paramdef>
<paramdef><type>name </type>
<parameter>refschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>reftable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>refcolumn</parameter></paramdef>
<paramdef><type>int </type>
<parameter>ovfactor</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>AddOverviewConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>ovtable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>ovcolumn</parameter></paramdef>
<paramdef><type>name </type>
<parameter>reftable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>refcolumn</parameter></paramdef>
<paramdef><type>int </type>
<parameter>ovfactor</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>
Adds constraints on a raster column that are used to display information
in the <varname>raster_overviews</varname> raster catalog.
</para>
<para>
The <varname>ovfactor</varname> parameter represents the scale multiplier
in the overview column: higher overview factors have lower resolution.
</para>
<para>
When the <varname>ovschema</varname> and <varname>refschema</varname>
parameters are omitted, the first table found scanning the
<varname>search_path</varname> will be used.
</para>
<para>Availability: 2.0.0</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting>
CREATE TABLE res1 AS SELECT
ST_AddBand(
ST_MakeEmptyRaster(1000, 1000, 0, 0, 2),
1, '8BSI'::text, -129, NULL
) r1;
CREATE TABLE res2 AS SELECT
ST_AddBand(
ST_MakeEmptyRaster(500, 500, 0, 0, 4),
1, '8BSI'::text, -129, NULL
) r2;
SELECT AddOverviewConstraints('res2', 'r2', 'res1', 'r1', 2);
-- verify if registered correctly in the raster_overviews view --
SELECT o_table_name ot, o_raster_column oc,
r_table_name rt, r_raster_column rc,
overview_factor f
FROM raster_overviews WHERE o_table_name = 'res2';
ot | oc | rt | rc | f
------+----+------+----+---
res2 | r2 | res1 | r1 | 2
(1 row)
</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_Raster_Overviews"/>,
<xref linkend="RT_DropOverviewConstraints"/>,
<xref linkend="RT_CreateOverview"/>,
<xref linkend="RT_AddRasterConstraints"/>
</para>
</refsection>
</refentry>
<refentry id="RT_DropOverviewConstraints">
<refnamediv>
<refname>DropOverviewConstraints</refname>
<refpurpose>Untag a raster column from being an overview of another.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>boolean <function>DropOverviewConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>ovschema</parameter></paramdef>
<paramdef><type>name </type>
<parameter>ovtable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>ovcolumn</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>boolean <function>DropOverviewConstraints</function></funcdef>
<paramdef><type>name </type>
<parameter>ovtable</parameter></paramdef>
<paramdef><type>name </type>
<parameter>ovcolumn</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>
Remove from a raster column the constraints used to show it as
being an overview of another in the <varname>raster_overviews</varname>
raster catalog.
</para>
<para>
When the <varname>ovschema</varname> parameter is omitted,
the first table found scanning the <varname>search_path</varname>
will be used.
</para>
<para>Availability: 2.0.0</para>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_Raster_Overviews"/>,
<xref linkend="RT_AddOverviewConstraints"/>,
<xref linkend="RT_DropRasterConstraints"/>
</para>
</refsection>
</refentry>
<refentry id="RT_PostGIS_GDAL_Version">
<refnamediv>
<refname>PostGIS_GDAL_Version</refname>
<refpurpose>Reports the version of the GDAL library in use by PostGIS.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcprototype>
<funcdef>text <function>PostGIS_GDAL_Version</function></funcdef>
<paramdef></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsection>
<title>Description</title>
<para>Reports the version of the GDAL library in use by PostGIS. Will also check and report if GDAL can find its data files.</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting>
SELECT PostGIS_GDAL_Version();
postgis_gdal_version
-----------------------------------
GDAL 1.11dev, released 2013/04/13
</programlisting>
</refsection>
<refsection>