*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 13897,13902 **** postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
--- 13897,13911 ----
         <entry><type>record</type></entry>
         <entry>Return information about a file</entry>
        </row>
+       <row>
+        <entry>
+         <literal><function>pg_execute_from_file(<parameter>filename</> <type>text</>
+ [, <parameter>variable</parameter> <type>text</type>, <parameter>value</parameter> <type>text</type>
+ [, ...] ]) )</function></literal>
+        </entry>
+        <entry><type>void</type></entry>
+        <entry>Executes the <acronym>SQL</> commands contained in a file, replacing given placeholders.</entry>
+       </row>
       </tbody>
      </tgroup>
     </table>
***************
*** 13935,13940 **** SELECT (pg_stat_file('filename')).modification;
--- 13944,13963 ----
  </programlisting>
     </para>
  
+    <indexterm>
+     <primary>pg_execute_from_file</primary>
+    </indexterm>
+    <para>
+     <function>pg_execute_from_file</> makes the server
+     execute <acronym>SQL</> commands to be found in a file. This function is
+     reserved to superusers.
+    </para>
+    <para>
+     The script might contain placeholders that will be replaced by the
+     values given in the <literal>VARIADIC</literal> arguments, which must be
+     a pair of variable names and values.
+    </para>
+ 
     <para>
      The functions shown in <xref linkend="functions-advisory-locks"> manage
      advisory locks.  For details about proper use of these functions, see
***************
*** 13957,13962 **** SELECT (pg_stat_file('filename')).modification;
--- 13980,13986 ----
         <entry><type>void</type></entry>
         <entry>Obtain exclusive advisory lock</entry>
        </row>
+ 
        <row>
         <entry>
          <literal><function>pg_advisory_lock(<parameter>key1</> <type>int</>, <parameter>key2</> <type>int</>)</function></literal>
*** a/src/backend/utils/adt/genfile.c
--- b/src/backend/utils/adt/genfile.c
***************
*** 7,12 ****
--- 7,13 ----
   * Copyright (c) 2004-2010, PostgreSQL Global Development Group
   *
   * Author: Andreas Pflug <pgadmin@pse-consulting.de>
+  *         Dimitri Fontaine <dimitri@2ndQuadrant.fr>
   *
   * IDENTIFICATION
   *	  src/backend/utils/adt/genfile.c
***************
*** 21,31 ****
--- 22,34 ----
  #include <dirent.h>
  
  #include "catalog/pg_type.h"
+ #include "executor/spi.h"
  #include "funcapi.h"
  #include "mb/pg_wchar.h"
  #include "miscadmin.h"
  #include "postmaster/syslogger.h"
  #include "storage/fd.h"
+ #include "utils/array.h"
  #include "utils/builtins.h"
  #include "utils/memutils.h"
  #include "utils/timestamp.h"
***************
*** 264,266 **** pg_ls_dir(PG_FUNCTION_ARGS)
--- 267,389 ----
  
  	SRF_RETURN_DONE(funcctx);
  }
+ 
+ /*
+  * Read a file then execute the SQL commands it contains.
+  *
+  * There's a variant accepting a VARIADIC text parameter containing
+  * placeholder variables and values, one after the other (so the variadic
+  * array length must be even).
+  *
+  * The main use case of the replacement facility is for setting the
+  * extension's schema, using @pg_extschema@ variable and a user given
+  * schema.
+  */
+ Datum
+ pg_execute_from_file(PG_FUNCTION_ARGS)
+ {
+ 	text	   *filename_t = PG_GETARG_TEXT_P(0);
+ 	char	   *filename;
+ 	FILE       *file;
+ 	int64       fsize = -1, nbytes;
+ 	struct stat fst;
+ 	char       *query_string = NULL;
+ 
+ 	if (!superuser())
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+ 				 (errmsg("must be superuser to get file information"))));
+ 
+ 	/*
+ 	 * Only superuser can call pg_execute_from_file, and CREATE EXTENSION
+ 	 * uses that too. Don't double check the PATH. Also note that
+ 	 * extension's install files are not in $PGDATA but `pg_config
+ 	 * --sharedir`.
+ 	 */
+ 	filename = text_to_cstring(filename_t);
+ 
+ 	if (stat(filename, &fst) < 0)
+ 		ereport(ERROR,
+ 				(errcode_for_file_access(),
+ 				 errmsg("could not stat file \"%s\": %m", filename)));
+ 
+ 	fsize = Int64GetDatum((int64) fst.st_size);
+ 
+ 	if ((file = AllocateFile(filename, PG_BINARY_R)) == NULL)
+ 		ereport(ERROR,
+ 				(errcode_for_file_access(),
+ 				 errmsg("could not open file \"%s\" for reading: %m",
+ 						filename)));
+ 
+ 	if (ferror(file))
+ 		ereport(ERROR,
+ 				(errcode_for_file_access(),
+ 				 errmsg("could not read file \"%s\": %m", filename)));
+ 
+ 	query_string = (char *)palloc((fsize+1)*sizeof(char));
+ 	memset(query_string, 0, fsize+1);
+ 	nbytes = fread(query_string, 1, (size_t) fsize, file);
+ 	pg_verifymbstr(query_string, nbytes, false);
+ 	FreeFile(file);
+ 
+ 	/*
+ 	 * Replace any given variable with its value, by calling replace_text
+ 	 * over each pair of arguments.
+ 	 */
+ 	if (PG_NARGS() == 2)
+ 	{
+ 		text       *src = cstring_to_text(query_string);
+ 		ArrayType  *array = PG_GETARG_ARRAYTYPE_P(1);
+ 		Datum	   *replacements;
+ 		int			nrep;
+ 		int			i;
+ 
+ 		Assert(ARR_ELEMTYPE(array) == TEXTOID);
+ 
+ 		deconstruct_array(array, TEXTOID, -1, false, 'i',
+ 						  &replacements, NULL, &nrep);
+ 
+ 		if (nrep % 2 != 0)
+ 			ereport(ERROR,
+ 					(errmsg("Expected pairs of variable names and values"),
+ 					 errdetail("Please give an even number of replacement parameters")));
+ 
+ 		for (i = 0; i < nrep; i+=2)
+ 		{
+ 			Datum	    rep;
+ 
+ 			elog(DEBUG1,
+ 				 "pg_execute_from_file replaces '%s' with '%s'",
+ 				 text_to_cstring(DatumGetTextP(replacements[i])),
+ 				 text_to_cstring(DatumGetTextP(replacements[i+1])));
+ 
+ 			rep = DirectFunctionCall3(replace_text,
+ 									  PointerGetDatum(src),
+ 									  replacements[i], replacements[i+1]);
+ 			src = DatumGetTextP(rep);
+ 		}
+ 		query_string = text_to_cstring(src);
+ 		elog(DEBUG2, "pg_execute_from_file: %s", query_string);
+ 	}
+ 
+ 	/*
+ 	 * We abuse some internal knowledge from spi.h here. As we don't know
+ 	 * which queries are going to get executed, we don't know what to expect
+ 	 * as an OK return code from SPI_execute().  We assume that
+ 	 * SPI_OK_CONNECT, SPI_OK_FINISH and SPI_OK_FETCH are quite improbable,
+ 	 * though, and the errors are negatives.  So a valid return code is
+ 	 * considered to be SPI_OK_UTILITY or anything from there.
+ 	 */
+ 	if (SPI_connect() != SPI_OK_CONNECT)
+ 		elog(ERROR, "SPI_connect failed");
+ 
+ 	if (SPI_execute(query_string, false, 0) < SPI_OK_UTILITY)
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATA_EXCEPTION),
+ 				 errmsg("File '%s' could not be executed", filename)));
+ 
+ 	if (SPI_finish() != SPI_OK_FINISH)
+ 		elog(ERROR, "SPI_finish failed");
+ 
+ 	PG_RETURN_VOID();
+ }
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
***************
*** 3386,3399 **** DESCR("reload configuration files");
  DATA(insert OID = 2622 ( pg_rotate_logfile		PGNSP PGUID 12 1 0 0 f f f t f v 0 0 16 "" _null_ _null_ _null_ _null_ pg_rotate_logfile _null_ _null_ _null_ ));
  DESCR("rotate log file");
  
! DATA(insert OID = 2623 ( pg_stat_file		PGNSP PGUID 12 1 0 0 f f f t f v 1 0 2249 "25" "{25,20,1184,1184,1184,1184,16}" "{i,o,o,o,o,o,o}" "{filename,size,access,modification,change,creation,isdir}" _null_ pg_stat_file _null_ _null_ _null_ ));
  DESCR("return file information");
! DATA(insert OID = 2624 ( pg_read_file		PGNSP PGUID 12 1 0 0 f f f t f v 3 0 25 "25 20 20" _null_ _null_ _null_ _null_ pg_read_file _null_ _null_ _null_ ));
  DESCR("read text from a file");
! DATA(insert OID = 2625 ( pg_ls_dir			PGNSP PGUID 12 1 1000 0 f f f t t v 1 0 25 "25" _null_ _null_ _null_ _null_ pg_ls_dir _null_ _null_ _null_ ));
  DESCR("list all files in a directory");
! DATA(insert OID = 2626 ( pg_sleep			PGNSP PGUID 12 1 0 0 f f f t f v 1 0 2278 "701" _null_ _null_ _null_ _null_ pg_sleep _null_ _null_ _null_ ));
  DESCR("sleep for the specified time in seconds");
  
  DATA(insert OID = 2971 (  text				PGNSP PGUID 12 1 0 0 f f f t f i 1 0 25 "16" _null_ _null_ _null_ _null_ booltext _null_ _null_ _null_ ));
  DESCR("convert boolean to text");
--- 3386,3403 ----
  DATA(insert OID = 2622 ( pg_rotate_logfile		PGNSP PGUID 12 1 0 0 f f f t f v 0 0 16 "" _null_ _null_ _null_ _null_ pg_rotate_logfile _null_ _null_ _null_ ));
  DESCR("rotate log file");
  
! DATA(insert OID = 2623 ( pg_stat_file			PGNSP PGUID 12 1 0 0 f f f t f v 1 0 2249 "25" "{25,20,1184,1184,1184,1184,16}" "{i,o,o,o,o,o,o}" "{filename,size,access,modification,change,creation,isdir}" _null_ pg_stat_file _null_ _null_ _null_ ));
  DESCR("return file information");
! DATA(insert OID = 2624 ( pg_read_file			PGNSP PGUID 12 1 0 0 f f f t f v 3 0 25 "25 20 20" _null_ _null_ _null_ _null_ pg_read_file _null_ _null_ _null_ ));
  DESCR("read text from a file");
! DATA(insert OID = 2625 ( pg_ls_dir				PGNSP PGUID 12 1 1000 0 f f f t t v 1 0 25 "25" _null_ _null_ _null_ _null_ pg_ls_dir _null_ _null_ _null_ ));
  DESCR("list all files in a directory");
! DATA(insert OID = 2626 ( pg_sleep				PGNSP PGUID 12 1 0 0 f f f t f v 1 0 2278 "701" _null_ _null_ _null_ _null_ pg_sleep _null_ _null_ _null_ ));
  DESCR("sleep for the specified time in seconds");
+ DATA(insert OID = 3627 ( pg_execute_from_file	PGNSP PGUID 12 1 0 0 f f f t f v 1 0 2278 "25" _null_ _null_ _null_ _null_ pg_execute_from_file _null_ _null_ _null_ ));
+ DESCR("execute queries read from a file");
+ DATA(insert OID = 3928 ( pg_execute_from_file	PGNSP PGUID 12 1 0 25 f f f t f v 2 0 2278 "25 25" "{25,25}" "{i,v}" _null_ _null_ pg_execute_from_file _null_ _null_ _null_ ));
+ DESCR("execute queries read from a file");
  
  DATA(insert OID = 2971 (  text				PGNSP PGUID 12 1 0 0 f f f t f i 1 0 25 "16" _null_ _null_ _null_ _null_ booltext _null_ _null_ _null_ ));
  DESCR("convert boolean to text");
*** a/src/include/utils/builtins.h
--- b/src/include/utils/builtins.h
***************
*** 442,447 **** extern Datum pg_relation_filepath(PG_FUNCTION_ARGS);
--- 442,448 ----
  extern Datum pg_stat_file(PG_FUNCTION_ARGS);
  extern Datum pg_read_file(PG_FUNCTION_ARGS);
  extern Datum pg_ls_dir(PG_FUNCTION_ARGS);
+ extern Datum pg_execute_from_file(PG_FUNCTION_ARGS);
  
  /* misc.c */
  extern Datum current_database(PG_FUNCTION_ARGS);