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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Server Programming Interface</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 9.2.24 Documentation" HREF="index.html"><LINK REL="UP" TITLE="Server Programming" HREF="server-programming.html"><LINK REL="PREVIOUS" TITLE="Environment Variables" HREF="plpython-envar.html"><LINK REL="NEXT" TITLE="Interface Functions" HREF="spi-interface.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2017-11-06T22:43:11"></HEAD ><BODY CLASS="CHAPTER" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" ><A HREF="index.html" >PostgreSQL 9.2.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="Environment Variables" HREF="plpython-envar.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="server-programming.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="Interface Functions" HREF="spi-interface.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="CHAPTER" ><H1 ><A NAME="SPI" ></A >Chapter 43. Server Programming Interface</H1 ><DIV CLASS="TOC" ><DL ><DT ><B >Table of Contents</B ></DT ><DT >43.1. <A HREF="spi-interface.html" >Interface Functions</A ></DT ><DD ><DL ><DT ><A HREF="spi-spi-connect.html" >SPI_connect</A > -- connect a procedure to the SPI manager</DT ><DT ><A HREF="spi-spi-finish.html" >SPI_finish</A > -- disconnect a procedure from the SPI manager</DT ><DT ><A HREF="spi-spi-push.html" >SPI_push</A > -- push SPI stack to allow recursive SPI usage</DT ><DT ><A HREF="spi-spi-pop.html" >SPI_pop</A > -- pop SPI stack to return from recursive SPI usage</DT ><DT ><A HREF="spi-spi-execute.html" >SPI_execute</A > -- execute a command</DT ><DT ><A HREF="spi-spi-exec.html" >SPI_exec</A > -- execute a read/write command</DT ><DT ><A HREF="spi-spi-execute-with-args.html" >SPI_execute_with_args</A > -- execute a command with out-of-line parameters</DT ><DT ><A HREF="spi-spi-prepare.html" >SPI_prepare</A > -- prepare a statement, without executing it yet</DT ><DT ><A HREF="spi-spi-prepare-cursor.html" >SPI_prepare_cursor</A > -- prepare a statement, without executing it yet</DT ><DT ><A HREF="spi-spi-prepare-params.html" >SPI_prepare_params</A > -- prepare a statement, without executing it yet</DT ><DT ><A HREF="spi-spi-getargcount.html" >SPI_getargcount</A > -- return the number of arguments needed by a statement prepared by <CODE CLASS="FUNCTION" >SPI_prepare</CODE ></DT ><DT ><A HREF="spi-spi-getargtypeid.html" >SPI_getargtypeid</A > -- return the data type OID for an argument of a statement prepared by <CODE CLASS="FUNCTION" >SPI_prepare</CODE ></DT ><DT ><A HREF="spi-spi-is-cursor-plan.html" >SPI_is_cursor_plan</A > -- return <TT CLASS="SYMBOL" >true</TT > if a statement prepared by <CODE CLASS="FUNCTION" >SPI_prepare</CODE > can be used with <CODE CLASS="FUNCTION" >SPI_cursor_open</CODE ></DT ><DT ><A HREF="spi-spi-execute-plan.html" >SPI_execute_plan</A > -- execute a statement prepared by <CODE CLASS="FUNCTION" >SPI_prepare</CODE ></DT ><DT ><A HREF="spi-spi-execute-plan-with-paramlist.html" >SPI_execute_plan_with_paramlist</A > -- execute a statement prepared by <CODE CLASS="FUNCTION" >SPI_prepare</CODE ></DT ><DT ><A HREF="spi-spi-execp.html" >SPI_execp</A > -- execute a statement in read/write mode</DT ><DT ><A HREF="spi-spi-cursor-open.html" >SPI_cursor_open</A > -- set up a cursor using a statement created with <CODE CLASS="FUNCTION" >SPI_prepare</CODE ></DT ><DT ><A HREF="spi-spi-cursor-open-with-args.html" >SPI_cursor_open_with_args</A > -- set up a cursor using a query and parameters</DT ><DT ><A HREF="spi-spi-cursor-open-with-paramlist.html" >SPI_cursor_open_with_paramlist</A > -- set up a cursor using parameters</DT ><DT ><A HREF="spi-spi-cursor-find.html" >SPI_cursor_find</A > -- find an existing cursor by name</DT ><DT ><A HREF="spi-spi-cursor-fetch.html" >SPI_cursor_fetch</A > -- fetch some rows from a cursor</DT ><DT ><A HREF="spi-spi-cursor-move.html" >SPI_cursor_move</A > -- move a cursor</DT ><DT ><A HREF="spi-spi-scroll-cursor-fetch.html" >SPI_scroll_cursor_fetch</A > -- fetch some rows from a cursor</DT ><DT ><A HREF="spi-spi-scroll-cursor-move.html" >SPI_scroll_cursor_move</A > -- move a cursor</DT ><DT ><A HREF="spi-spi-cursor-close.html" >SPI_cursor_close</A > -- close a cursor</DT ><DT ><A HREF="spi-spi-keepplan.html" >SPI_keepplan</A > -- save a prepared statement</DT ><DT ><A HREF="spi-spi-saveplan.html" >SPI_saveplan</A > -- save a prepared statement</DT ></DL ></DD ><DT >43.2. <A HREF="spi-interface-support.html" >Interface Support Functions</A ></DT ><DD ><DL ><DT ><A HREF="spi-spi-fname.html" >SPI_fname</A > -- determine the column name for the specified column number</DT ><DT ><A HREF="spi-spi-fnumber.html" >SPI_fnumber</A > -- determine the column number for the specified column name</DT ><DT ><A HREF="spi-spi-getvalue.html" >SPI_getvalue</A > -- return the string value of the specified column</DT ><DT ><A HREF="spi-spi-getbinval.html" >SPI_getbinval</A > -- return the binary value of the specified column</DT ><DT ><A HREF="spi-spi-gettype.html" >SPI_gettype</A > -- return the data type name of the specified column</DT ><DT ><A HREF="spi-spi-gettypeid.html" >SPI_gettypeid</A > -- return the data type <ACRONYM CLASS="ACRONYM" >OID</ACRONYM > of the specified column</DT ><DT ><A HREF="spi-spi-getrelname.html" >SPI_getrelname</A > -- return the name of the specified relation</DT ><DT ><A HREF="spi-spi-getnspname.html" >SPI_getnspname</A > -- return the namespace of the specified relation</DT ></DL ></DD ><DT >43.3. <A HREF="spi-memory.html" >Memory Management</A ></DT ><DD ><DL ><DT ><A HREF="spi-spi-palloc.html" >SPI_palloc</A > -- allocate memory in the upper executor context</DT ><DT ><A HREF="spi-realloc.html" >SPI_repalloc</A > -- reallocate memory in the upper executor context</DT ><DT ><A HREF="spi-spi-pfree.html" >SPI_pfree</A > -- free memory in the upper executor context</DT ><DT ><A HREF="spi-spi-copytuple.html" >SPI_copytuple</A > -- make a copy of a row in the upper executor context</DT ><DT ><A HREF="spi-spi-returntuple.html" >SPI_returntuple</A > -- prepare to return a tuple as a Datum</DT ><DT ><A HREF="spi-spi-modifytuple.html" >SPI_modifytuple</A > -- create a row by replacing selected fields of a given row</DT ><DT ><A HREF="spi-spi-freetuple.html" >SPI_freetuple</A > -- free a row allocated in the upper executor context</DT ><DT ><A HREF="spi-spi-freetupletable.html" >SPI_freetuptable</A > -- free a row set created by <CODE CLASS="FUNCTION" >SPI_execute</CODE > or a similar function</DT ><DT ><A HREF="spi-spi-freeplan.html" >SPI_freeplan</A > -- free a previously saved prepared statement</DT ></DL ></DD ><DT >43.4. <A HREF="spi-visibility.html" >Visibility of Data Changes</A ></DT ><DT >43.5. <A HREF="spi-examples.html" >Examples</A ></DT ></DL ></DIV ><P > The <I CLASS="FIRSTTERM" >Server Programming Interface</I > (<ACRONYM CLASS="ACRONYM" >SPI</ACRONYM >) gives writers of user-defined <ACRONYM CLASS="ACRONYM" >C</ACRONYM > functions the ability to run <ACRONYM CLASS="ACRONYM" >SQL</ACRONYM > commands inside their functions. <ACRONYM CLASS="ACRONYM" >SPI</ACRONYM > is a set of interface functions to simplify access to the parser, planner, and executor. <ACRONYM CLASS="ACRONYM" >SPI</ACRONYM > also does some memory management. </P ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B > The available procedural languages provide various means to execute SQL commands from procedures. Most of these facilities are based on SPI, so this documentation might be of use for users of those languages as well. </P ></BLOCKQUOTE ></DIV ><P > To avoid misunderstanding we'll use the term <SPAN CLASS="QUOTE" >"function"</SPAN > when we speak of <ACRONYM CLASS="ACRONYM" >SPI</ACRONYM > interface functions and <SPAN CLASS="QUOTE" >"procedure"</SPAN > for a user-defined C-function that is using <ACRONYM CLASS="ACRONYM" >SPI</ACRONYM >. </P ><P > Note that if a command invoked via SPI fails, then control will not be returned to your procedure. Rather, the transaction or subtransaction in which your procedure executes will be rolled back. (This might seem surprising given that the SPI functions mostly have documented error-return conventions. Those conventions only apply for errors detected within the SPI functions themselves, however.) It is possible to recover control after an error by establishing your own subtransaction surrounding SPI calls that might fail. This is not currently documented because the mechanisms required are still in flux. </P ><P > <ACRONYM CLASS="ACRONYM" >SPI</ACRONYM > functions return a nonnegative result on success (either via a returned integer value or in the global variable <TT CLASS="VARNAME" >SPI_result</TT >, as described below). On error, a negative result or <TT CLASS="SYMBOL" >NULL</TT > will be returned. </P ><P > Source code files that use SPI must include the header file <TT CLASS="FILENAME" >executor/spi.h</TT >. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="plpython-envar.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="spi-interface.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Environment Variables</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="server-programming.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Interface Functions</TD ></TR ></TABLE ></DIV ></BODY ></HTML >