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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-13 13:44:03 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-13 13:44:03 +0000
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downloadpostgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.tar.xz
postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.zip
Adding upstream version 16.2.upstream/16.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>59.3. Foreign Data Wrapper Helper Functions</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="fdw-callbacks.html" title="59.2. Foreign Data Wrapper Callback Routines" /><link rel="next" href="fdw-planning.html" title="59.4. Foreign Data Wrapper Query Planning" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">59.3. Foreign Data Wrapper Helper Functions</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="fdw-callbacks.html" title="59.2. Foreign Data Wrapper Callback Routines">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="fdwhandler.html" title="Chapter 59. Writing a Foreign Data Wrapper">Up</a></td><th width="60%" align="center">Chapter 59. Writing a Foreign Data Wrapper</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="fdw-planning.html" title="59.4. Foreign Data Wrapper Query Planning">Next</a></td></tr></table><hr /></div><div class="sect1" id="FDW-HELPERS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">59.3. Foreign Data Wrapper Helper Functions <a href="#FDW-HELPERS" class="id_link">#</a></h2></div></div></div><p>
+ Several helper functions are exported from the core server so that
+ authors of foreign data wrappers can get easy access to attributes of
+ FDW-related objects, such as FDW options.
+ To use any of these functions, you need to include the header file
+ <code class="filename">foreign/foreign.h</code> in your source file.
+ That header also defines the struct types that are returned by
+ these functions.
+ </p><p>
+</p><pre class="programlisting">
+ForeignDataWrapper *
+GetForeignDataWrapperExtended(Oid fdwid, bits16 flags);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignDataWrapper</code>
+ object for the foreign-data wrapper with the given OID. A
+ <code class="structname">ForeignDataWrapper</code> object contains properties
+ of the FDW (see <code class="filename">foreign/foreign.h</code> for details).
+ <code class="structfield">flags</code> is a bitwise-or'd bit mask indicating
+ an extra set of options. It can take the value
+ <code class="literal">FDW_MISSING_OK</code>, in which case a <code class="literal">NULL</code>
+ result is returned to the caller instead of an error for an undefined
+ object.
+ </p><p>
+</p><pre class="programlisting">
+ForeignDataWrapper *
+GetForeignDataWrapper(Oid fdwid);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignDataWrapper</code>
+ object for the foreign-data wrapper with the given OID. A
+ <code class="structname">ForeignDataWrapper</code> object contains properties
+ of the FDW (see <code class="filename">foreign/foreign.h</code> for details).
+ </p><p>
+</p><pre class="programlisting">
+ForeignServer *
+GetForeignServerExtended(Oid serverid, bits16 flags);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignServer</code> object
+ for the foreign server with the given OID. A
+ <code class="structname">ForeignServer</code> object contains properties
+ of the server (see <code class="filename">foreign/foreign.h</code> for details).
+ <code class="structfield">flags</code> is a bitwise-or'd bit mask indicating
+ an extra set of options. It can take the value
+ <code class="literal">FSV_MISSING_OK</code>, in which case a <code class="literal">NULL</code>
+ result is returned to the caller instead of an error for an undefined
+ object.
+ </p><p>
+</p><pre class="programlisting">
+ForeignServer *
+GetForeignServer(Oid serverid);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignServer</code> object
+ for the foreign server with the given OID. A
+ <code class="structname">ForeignServer</code> object contains properties
+ of the server (see <code class="filename">foreign/foreign.h</code> for details).
+ </p><p>
+</p><pre class="programlisting">
+UserMapping *
+GetUserMapping(Oid userid, Oid serverid);
+</pre><p>
+
+ This function returns a <code class="structname">UserMapping</code> object for
+ the user mapping of the given role on the given server. (If there is no
+ mapping for the specific user, it will return the mapping for
+ <code class="literal">PUBLIC</code>, or throw error if there is none.) A
+ <code class="structname">UserMapping</code> object contains properties of the
+ user mapping (see <code class="filename">foreign/foreign.h</code> for details).
+ </p><p>
+</p><pre class="programlisting">
+ForeignTable *
+GetForeignTable(Oid relid);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignTable</code> object for
+ the foreign table with the given OID. A
+ <code class="structname">ForeignTable</code> object contains properties of the
+ foreign table (see <code class="filename">foreign/foreign.h</code> for details).
+ </p><p>
+</p><pre class="programlisting">
+List *
+GetForeignColumnOptions(Oid relid, AttrNumber attnum);
+</pre><p>
+
+ This function returns the per-column FDW options for the column with the
+ given foreign table OID and attribute number, in the form of a list of
+ <code class="structname">DefElem</code>. NIL is returned if the column has no
+ options.
+ </p><p>
+ Some object types have name-based lookup functions in addition to the
+ OID-based ones:
+ </p><p>
+</p><pre class="programlisting">
+ForeignDataWrapper *
+GetForeignDataWrapperByName(const char *name, bool missing_ok);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignDataWrapper</code>
+ object for the foreign-data wrapper with the given name. If the wrapper
+ is not found, return NULL if missing_ok is true, otherwise raise an
+ error.
+ </p><p>
+</p><pre class="programlisting">
+ForeignServer *
+GetForeignServerByName(const char *name, bool missing_ok);
+</pre><p>
+
+ This function returns a <code class="structname">ForeignServer</code> object
+ for the foreign server with the given name. If the server is not found,
+ return NULL if missing_ok is true, otherwise raise an error.
+ </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="fdw-callbacks.html" title="59.2. Foreign Data Wrapper Callback Routines">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="fdwhandler.html" title="Chapter 59. Writing a Foreign Data Wrapper">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="fdw-planning.html" title="59.4. Foreign Data Wrapper Query Planning">Next</a></td></tr><tr><td width="40%" align="left" valign="top">59.2. Foreign Data Wrapper Callback Routines </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 59.4. Foreign Data Wrapper Query Planning</td></tr></table></div></body></html> \ No newline at end of file
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