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diff --git a/doc/src/sgml/html/fdw-helpers.html b/doc/src/sgml/html/fdw-helpers.html new file mode 100644 index 0000000..44fa319 --- /dev/null +++ b/doc/src/sgml/html/fdw-helpers.html @@ -0,0 +1,114 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!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>56.3. 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 V1.79.1" /><link rel="prev" href="fdw-callbacks.html" title="56.2. Foreign Data Wrapper Callback Routines" /><link rel="next" href="fdw-planning.html" title="56.4. Foreign Data Wrapper Query Planning" /></head><body id="docContent" class="container-fluid col-10"><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">56.3. Foreign Data Wrapper Helper Functions</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="fdw-callbacks.html" title="56.2. Foreign Data Wrapper Callback Routines">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="fdwhandler.html" title="Chapter 56. Writing a Foreign Data Wrapper">Up</a></td><th width="60%" align="center">Chapter 56. Writing a Foreign Data Wrapper</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 13.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="fdw-planning.html" title="56.4. Foreign Data Wrapper Query Planning">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="FDW-HELPERS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">56.3. Foreign Data Wrapper Helper Functions</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 xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navfooter"><hr></hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="fdw-callbacks.html" title="56.2. Foreign Data Wrapper Callback Routines">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="fdwhandler.html" title="Chapter 56. Writing a Foreign Data Wrapper">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="fdw-planning.html" title="56.4. Foreign Data Wrapper Query Planning">Next</a></td></tr><tr><td width="40%" align="left" valign="top">56.2. Foreign Data Wrapper Callback Routines </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 13.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 56.4. Foreign Data Wrapper Query Planning</td></tr></table></div></body></html>
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