<?xml version="1.0" encoding="UTF-8"?>
<sect1 id="PostGIS_GUC">
<sect1info>
<abstract>
<para>This section lists custom PostGIS Grand Unified Custom Variables (GUC).
These can be set globally, by database, by session or by transaction. Best set at global or database level.</para>
</abstract>
</sect1info>
<title>Grand Unified Custom Variables (GUCs)</title>
<refentry id="postgis_backend">
<refnamediv>
<refname>postgis.backend</refname>
<refpurpose>The backend to service a function where GEOS and SFCGAL overlap. Options: geos or sfcgal. Defaults to geos.</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>This GUC is only relevant if you compiled PostGIS with sfcgal support. By default <varname>geos</varname> backend is used for functions where both GEOS and SFCGAL have the same named function. This variable allows you to override and make sfcgal the backend to service the request.</para>
<para>Availability: 2.1.0</para>
</refsection>
<refsection>
<title>Examples</title>
<para>Sets backend just for life of connection</para>
<programlisting>set postgis.backend = sfcgal;</programlisting>
<para>Sets backend for new connections to database</para>
<programlisting>ALTER DATABASE mygisdb SET postgis.backend = sfcgal;</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para><xref linkend="reference_sfcgal" /></para>
</refsection>
</refentry>
<refentry id="postgis_gdal_datapath">
<refnamediv>
<refname>postgis.gdal_datapath</refname>
<refpurpose>
A configuration option to assign the value of GDAL's GDAL_DATA option. If not set, the environmentally set GDAL_DATA variable is used.
</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A PostgreSQL GUC variable for setting the value of GDAL's GDAL_DATA option. The <varname>postgis.gdal_datapath</varname> value should be the complete physical path to GDAL's data files.
</para>
<para>
This configuration option is of most use for Windows platforms where GDAL's data files path is not hard-coded. This option should also be set when GDAL's data files are not located in GDAL's expected path.
</para>
<note>
<para>
This option can be set in PostgreSQL's configuration file postgresql.conf. It can also be set by connection or transaction.
</para>
</note>
<para>Availability: 2.2.0</para>
<note>
<para>
Additional information about GDAL_DATA is available at GDAL's <ulink url="http://trac.osgeo.org/gdal/wiki/ConfigOptions">Configuration Options</ulink>.
</para>
</note>
</refsection>
<refsection>
<title>Examples</title>
<para>Set and reset <varname>postgis.gdal_datapath</varname></para>
<programlisting>
SET postgis.gdal_datapath TO '/usr/local/share/gdal.hidden';
SET postgis.gdal_datapath TO default;
</programlisting>
<para>Setting on windows for a particular database</para>
<programlisting>ALTER DATABASE gisdb
SET postgis.gdal_datapath = 'C:/Program Files/PostgreSQL/9.3/gdal-data';</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_PostGIS_GDAL_Version" />, <xref linkend="RT_ST_Transform" />
</para>
</refsection>
</refentry>
<refentry id="postgis_gdal_enabled_drivers">
<refnamediv>
<refname>postgis.gdal_enabled_drivers</refname>
<refpurpose>
A configuration option to set the enabled GDAL drivers in the PostGIS environment. Affects the GDAL configuration variable GDAL_SKIP.
</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A configuration option to set the enabled GDAL drivers in the PostGIS environment. Affects the GDAL configuration variable GDAL_SKIP. This option can be set in PostgreSQL's configuration file: postgresql.conf. It can also be set by connection or transaction.
</para>
<para>
The initial value of <varname>postgis.gdal_enabled_drivers</varname> may also be set by passing the environment variable <varname>POSTGIS_GDAL_ENABLED_DRIVERS</varname> with the list of enabled drivers to the process starting PostgreSQL.
</para>
<para>
Enabled GDAL specified drivers can be specified by the driver's short-name or code. Driver short-names or codes can be found at <ulink url="http://www.gdal.org/formats_list.html">GDAL Raster Formats</ulink>. Multiple drivers can be specified by putting a space between each driver.
</para>
<note>
<para>
There are three special codes available for <varname>postgis.gdal_enabled_drivers</varname>. The codes are case-sensitive.
<itemizedlist>
<listitem>
<para><varname>DISABLE_ALL</varname> disables all GDAL drivers. If present, <varname>DISABLE_ALL</varname> overrides all other values in <varname>postgis.gdal_enabled_drivers</varname>.</para>
</listitem>
<listitem>
<para><varname>ENABLE_ALL</varname> enables all GDAL drivers.</para>
</listitem>
<listitem>
<para><varname>VSICURL</varname> enables GDAL's <varname>/vsicurl/</varname> virtual file system.</para>
</listitem>
</itemizedlist>
</para>
<para>
When <varname>postgis.gdal_enabled_drivers</varname> is set to DISABLE_ALL, attempts to use out-db rasters, ST_FromGDALRaster(), ST_AsGDALRaster(), ST_AsTIFF(), ST_AsJPEG() and ST_AsPNG() will result in error messages.
</para>
</note>
<note>
<para>
In the standard PostGIS installation, <varname>postgis.gdal_enabled_drivers</varname> is set to DISABLE_ALL.
</para>
</note>
<note>
<para>
Additional information about GDAL_SKIP is available at GDAL's <ulink url="http://trac.osgeo.org/gdal/wiki/ConfigOptions">Configuration Options</ulink>.
</para>
</note>
<para>Availability: 2.2.0</para>
</refsection>
<refsection>
<title>Examples</title>
<para>Set and reset <varname>postgis.gdal_enabled_drivers</varname></para>
<para>Sets backend for all new connections to database</para>
<programlisting>ALTER DATABASE mygisdb SET postgis.gdal_enabled_drivers TO 'GTiff PNG JPEG';</programlisting>
<para>Sets default enabled drivers for all new connections to server. Requires super user access and PostgreSQL 9.4+.
Also note that database, session, and user settings override this.</para>
<programlisting>ALTER SYSTEM SET postgis.gdal_enabled_drivers TO 'GTiff PNG JPEG';
SELECT pg_reload_conf();
</programlisting>
<programlisting>
SET postgis.gdal_enabled_drivers TO 'GTiff PNG JPEG';
SET postgis.gdal_enabled_drivers = default;
</programlisting>
<para>Enable all GDAL Drivers</para>
<programlisting>
SET postgis.gdal_enabled_drivers = 'ENABLE_ALL';
</programlisting>
<para>Disable all GDAL Drivers</para>
<programlisting>
SET postgis.gdal_enabled_drivers = 'DISABLE_ALL';
</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="RT_ST_FromGDALRaster" />,
<xref linkend="RT_ST_AsGDALRaster" />,
<xref linkend="RT_ST_AsTIFF" />,
<xref linkend="RT_ST_AsPNG" />,
<xref linkend="RT_ST_AsJPEG" />,
<xref linkend="postgis_enable_outdb_rasters" />
</para>
</refsection>
</refentry>
<refentry id="postgis_enable_outdb_rasters">
<refnamediv>
<refname>postgis.enable_outdb_rasters</refname>
<refpurpose>
A boolean configuration option to enable access to out-db raster bands.
</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A boolean configuration option to enable access to out-db raster bands. This option can be set in PostgreSQL's configuration file: postgresql.conf. It can also be set by connection or transaction.
</para>
<para>
The initial value of <varname>postgis.enable_outdb_rasters</varname> may also be set by passing the environment variable <varname>POSTGIS_ENABLE_OUTDB_RASTERS</varname> with a non-zero value to the process starting PostgreSQL.
</para>
<note>
<para>
Even if <varname>postgis.enable_outdb_rasters</varname> is True, the GUC <varname>postgis.gdal_enabled_drivers</varname> determines the accessible raster formats.
</para>
</note>
<note>
<para>
In the standard PostGIS installation, <varname>postgis.enable_outdb_rasters</varname> is set to False.
</para>
</note>
<para>Availability: 2.2.0</para>
</refsection>
<refsection>
<title>Examples</title>
<para>Set and reset <varname>postgis.enable_outdb_rasters</varname> for current session</para>
<programlisting>
SET postgis.enable_outdb_rasters TO True;
SET postgis.enable_outdb_rasters = default;
SET postgis.enable_outdb_rasters = True;
SET postgis.enable_outdb_rasters = False;
</programlisting>
<para>Set for specific database</para>
<programlisting>
ALTER DATABASE gisdb SET postgis.enable_outdb_rasters = true;
</programlisting>
<para>Setting for whole database cluster. You need to reconnect to the database for changes to take effect.</para>
<programlisting>
--writes to postgres.auto.conf
ALTER SYSTEM postgis.enable_outdb_rasters = true;
--Reloads postgres conf
SELECT pg_reload_conf();
</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="postgis_gdal_enabled_drivers" />
<xref linkend="postgis_gdal_vsi_options" />
</para>
</refsection>
</refentry>
<refentry id="postgis_gdal_vsi_options">
<refnamediv>
<refname>postgis.gdal_config_options</refname>
<refpurpose>
A string configuration to set options used when working with an out-db raster.
</refpurpose>
</refnamediv>
<refsection>
<title>Description</title>
<para>
A string configuration to set options used when working with an out-db raster. <ulink url="http://trac.osgeo.org/gdal/wiki/ConfigOptions">Configuration options</ulink> control things like how much space GDAL allocates to local data cache, whether to read overviews, and what access keys to use for remote out-db data sources.
</para>
<para>Availability: 3.2.0</para>
</refsection>
<refsection>
<title>Examples</title>
<para>Set <varname>postgis.gdal_vsi_options</varname> for current session:</para>
<programlisting>
SET postgis.gdal_config_options = 'AWS_ACCESS_KEY_ID=xxxxxxxxxxxxxxx AWS_SECRET_ACCESS_KEY=yyyyyyyyyyyyyyyyyyyyyyyyyy';
</programlisting>
<para>Set <varname>postgis.gdal_vsi_options</varname> just for the <emphasis>current transaction</emphasis> using the <varname>LOCAL</varname> keyword:</para>
<programlisting>
SET LOCAL postgis.gdal_config_options = 'AWS_ACCESS_KEY_ID=xxxxxxxxxxxxxxx AWS_SECRET_ACCESS_KEY=yyyyyyyyyyyyyyyyyyyyyyyyyy';
</programlisting>
</refsection>
<refsection>
<title>See Also</title>
<para>
<xref linkend="postgis_enable_outdb_rasters" />
<xref linkend="postgis_gdal_enabled_drivers" />
</para>
</refsection>
</refentry>
</sect1>