Please apply attached patch to contrib/dblink. It adds named persistent

connections to dblink.

Shridhar Daithanka

contrib/dblink/README.dblink

@@ -4,8 +4,11 @@
  * Functions returning results from a remote database
  *
  * Joe Conway <mail@joeconway.com>
+ * And contributors:
+ * Darko Prenosil <Darko.Prenosil@finteh.hr>
+ * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * Copyright (c) 2001, 2002 by PostgreSQL Global Development Group
+ * Copyright (c) 2001, 2002, 2003 by PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  * 
  * Permission to use, copy, modify, and distribute this software and its
@@ -27,14 +30,16 @@
  *
  */
 
-Version 0.5 (25 August, 2002):
-  Major overhaul to work with new backend "table function" capability. Removed
-  dblink_strtok() and dblink_replace() functions because they are now
-  available as backend functions (split() and replace() respectively).
-  Tested under Linux (Red Hat 7.3) and PostgreSQL 7.3devel. This version
-  is no longer backwards portable to PostgreSQL 7.2.
+Version 0.6 (14 June, 2003):
+  Completely removed previously deprecated functions. Added ability
+  to create "named" persistent connections in addition to the single global
+  "unnamed" persistent connection.
+  Tested under Linux (Red Hat 9) and PostgreSQL 7.4devel.
 
 Release Notes:
+  Version 0.6
+    - functions deprecated in 0.5 have been removed
+    - added ability to create "named" persistent connections
   Version 0.5
     - dblink now supports use directly as a table function; this is the new
       preferred usage going forward
@@ -87,35 +92,51 @@ Installation:
      connection
      ------------
      dblink_connect(text) RETURNS text
-       - opens a connection that will persist for duration of current
+       - opens an unnamed connection that will persist for duration of
+         current backend or until it is disconnected
+     dblink_connect(text,text) RETURNS text
+       - opens a named connection that will persist for duration of current
          backend or until it is disconnected
      dblink_disconnect() RETURNS text
-       - disconnects a persistent connection
+       - disconnects the unnamed persistent connection
+     dblink_disconnect(text) RETURNS text
+       - disconnects a named persistent connection
 
      cursor
      ------------
      dblink_open(text,text) RETURNS text
-       - opens a cursor using connection already opened with dblink_connect()
-         that will persist for duration of current backend or until it is
-         closed
+       - opens a cursor using unnamed connection already opened with
+         dblink_connect() that will persist for duration of current backend
+         or until it is closed
+     dblink_open(text,text,text) RETURNS text
+       - opens a cursor using a named connection already opened with
+         dblink_connect() that will persist for duration of current backend
+         or until it is closed
      dblink_fetch(text, int) RETURNS setof record
-       - fetches data from an already opened cursor
+       - fetches data from an already opened cursor on the unnamed connection
+     dblink_fetch(text, text, int) RETURNS setof record
+       - fetches data from an already opened cursor on a named connection
      dblink_close(text) RETURNS text
-       - closes a cursor
+       - closes a cursor on the unnamed connection
+     dblink_close(text,text) RETURNS text
+       - closes a cursor on a named connection
 
      query
      ------------
      dblink(text,text) RETURNS setof record
-       - returns a set of results from remote SELECT query
-         (Note: comment out in dblink.sql to use deprecated version)
+       - returns a set of results from remote SELECT query; the first argument
+         is either a connection string, or the name of an already opened
+         persistant connection
      dblink(text) RETURNS setof record
-       - returns a set of results from remote SELECT query, using connection
-         already opened with dblink_connect()
+       - returns a set of results from remote SELECT query, using the unnamed
+         connection already opened with dblink_connect()
 
      execute
      ------------
      dblink_exec(text, text) RETURNS text
-       - executes an INSERT/UPDATE/DELETE query remotely
+       - executes an INSERT/UPDATE/DELETE query remotely; the first argument
+         is either a connection string, or the name of an already opened
+         persistant connection
      dblink_exec(text) RETURNS text
        - executes an INSERT/UPDATE/DELETE query remotely, using connection
          already opened with dblink_connect()
@@ -136,19 +157,6 @@ Installation:
        - builds an update statement using a local tuple, replacing the
          selection key field values with alternate supplied values
 
-  Not installed by default
-     deprecated
-     ------------
-     dblink(text,text) RETURNS setof int
-       - *DEPRECATED* returns a resource id for results from remote query
-         (Note: must uncomment in dblink.sql to use)
-     dblink_tok(int,int) RETURNS text
-       - *DEPRECATED* extracts and returns individual field results; used
-         only in conjunction with the *DEPRECATED* form of dblink
-         (Note: must uncomment in dblink.sql to use)
-     dblink_last_oid(int) RETURNS oid
-       - *DEPRECATED* returns the last inserted oid
-
 Documentation:
 
   Note: Parameters representing relation names must include double

contrib/dblink/dblink.c

@@ -4,8 +4,11 @@
  * Functions returning results from a remote database
  *
  * Joe Conway <mail@joeconway.com>
+ * And contributors:
+ * Darko Prenosil <Darko.Prenosil@finteh.hr>
+ * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * Copyright (c) 2001, 2002 by PostgreSQL Global Development Group
+ * Copyright (c) 2001, 2002, 2003 by PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
  * Permission to use, copy, modify, and distribute this software and its
@@ -27,9 +30,7 @@
  *
  */
 #include "postgres.h"
-
 #include "libpq-fe.h"
-
 #include "fmgr.h"
 #include "funcapi.h"
 #include "access/tupdesc.h"
@@ -51,13 +52,27 @@
 #include "utils/array.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
+#include "utils/palloc.h"
+#include "utils/dynahash.h"
+#include "utils/hsearch.h"
+#include "utils/memutils.h"
 
 #include "dblink.h"
 
+typedef struct remoteConn
+{
+	PGconn *con;			/* Hold the remote connection */
+	bool remoteTrFlag;		/* Indicates whether or not a transaction
+							 * on remote database is in progress*/
+} remoteConn;
+
 /*
  * Internal declarations
  */
-static dblink_results *init_dblink_results(MemoryContext fn_mcxt);
+static remoteConn *getConnectionByName(const char *name);
+static HTAB *createConnHash(void);
+static bool createNewConnection(const char *name,remoteConn *con);
+static void deleteConnection(const char *name);
 static char **get_pkey_attnames(Oid relid, int16 *numatts);
 static char *get_sql_insert(Oid relid, int16 *pkattnums, int16 pknumatts, char **src_pkattvals, char **tgt_pkattvals);
 static char *get_sql_delete(Oid relid, int16 *pkattnums, int16 pknumatts, char **tgt_pkattvals);
@@ -67,17 +82,32 @@ static char *quote_ident_cstr(char *rawstr);
 static int16 get_attnum_pk_pos(int16 *pkattnums, int16 pknumatts, int16 key);
 static HeapTuple get_tuple_of_interest(Oid relid, int16 *pkattnums, int16 pknumatts, char **src_pkattvals);
 static Oid	get_relid_from_relname(text *relname_text);
-static dblink_results *get_res_ptr(int32 res_id_index);
-static void append_res_ptr(dblink_results * results);
-static void remove_res_ptr(dblink_results * results);
 static TupleDesc pgresultGetTupleDesc(PGresult *res);
 static char *generate_relation_name(Oid relid);
 
 /* Global */
-List	   *res_id = NIL;
-int			res_id_index = 0;
-PGconn	   *persistent_conn = NULL;
+List   *res_id = NIL;
+int		res_id_index = 0;
+PGconn *persistent_conn = NULL;
+static HTAB *remoteConnHash=NULL;
+
+/* 
+Following is list that holds multiple remote connections.
+Calling convention of each dblink function changes to accept
+connection name as the first parameter. The connection list is 
+much like ecpg e.g. a mapping between a name and a PGconn object.
+*/
+
+typedef struct remoteConnHashEnt
+{
+	char		name[NAMEDATALEN];
+	remoteConn *rcon;
+} remoteConnHashEnt;
+
+/* initial number of connection hashes */
+#define NUMCONN 16
 
+/* general utility */
 #define GET_TEXT(cstrp) DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(cstrp)))
 #define GET_STR(textp) DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(textp)))
 #define xpfree(var_) \
@@ -88,6 +118,41 @@ PGconn	   *persistent_conn = NULL;
 			var_ = NULL; \
 		} \
 	} while (0)
+#define DBLINK_RES_ERROR(p1, p2) \
+	do { \
+			msg = pstrdup(PQerrorMessage(conn)); \
+			if (res) \
+				PQclear(res); \
+			elog(ERROR, "%s: %s: %s", p1, p2, msg); \
+	} while (0)
+#define DBLINK_CONN_NOT_AVAIL(p1) \
+	do { \
+		if(conname) \
+			elog(ERROR, "%s: connection %s not available", p1, conname); \
+		else \
+			elog(ERROR, "%s: connection not available", p1); \
+	} while (0)
+#define DBLINK_GET_CONN(p1) \
+	do { \
+			char *conname_or_str = GET_STR(PG_GETARG_TEXT_P(0)); \
+			rcon = getConnectionByName(conname_or_str); \
+			if(rcon) \
+			{ \
+				conn = rcon->con; \
+				freeconn = false; \
+			} \
+			else \
+			{ \
+				connstr = conname_or_str; \
+				conn = PQconnectdb(connstr); \
+				if (PQstatus(conn) == CONNECTION_BAD) \
+				{ \
+					msg = pstrdup(PQerrorMessage(conn)); \
+					PQfinish(conn); \
+					elog(ERROR, "%s: connection error: %s", p1, msg); \
+				} \
+			} \
+	} while (0)
 
 
 /*
@@ -97,28 +162,52 @@ PG_FUNCTION_INFO_V1(dblink_connect);
 Datum
 dblink_connect(PG_FUNCTION_ARGS)
 {
-	char	   *connstr = GET_STR(PG_GETARG_TEXT_P(0));
+	char	   *connstr = NULL;
+	char	   *connname = NULL;
 	char	   *msg;
-	text	   *result_text;
 	MemoryContext oldcontext;
+	PGconn	   *conn = NULL;
+	remoteConn *rcon = NULL;
 
-	if (persistent_conn != NULL)
-		PQfinish(persistent_conn);
+	if(PG_NARGS()==2)
+	{
+		connstr = GET_STR(PG_GETARG_TEXT_P(1));
+		connname = GET_STR(PG_GETARG_TEXT_P(0));
+	}
+	else if(PG_NARGS()==1)
+		connstr = GET_STR(PG_GETARG_TEXT_P(0));
 
 	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
-	persistent_conn = PQconnectdb(connstr);
+
+	if(connname)
+		rcon=(remoteConn *) palloc(sizeof(remoteConn));
+	conn = PQconnectdb(connstr);
+
 	MemoryContextSwitchTo(oldcontext);
 
-	if (PQstatus(persistent_conn) == CONNECTION_BAD)
+	if (PQstatus(conn) == CONNECTION_BAD)
 	{
-		msg = pstrdup(PQerrorMessage(persistent_conn));
-		PQfinish(persistent_conn);
-		persistent_conn = NULL;
+		msg = pstrdup(PQerrorMessage(conn));
+		PQfinish(conn);
+		if(rcon)
+			pfree(rcon);
 		elog(ERROR, "dblink_connect: connection error: %s", msg);
 	}
 
-	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum("OK")));
-	PG_RETURN_TEXT_P(result_text);
+	if(connname)
+	{
+		rcon->con = conn;
+		if(createNewConnection(connname, rcon) == false)
+	 	{
+			PQfinish(conn);
+			pfree(rcon);
+			elog(ERROR, "dblink_connect: cannot save named connection");
+		}
+	}
+	else
+		persistent_conn = conn;
+
+	PG_RETURN_TEXT_P(GET_TEXT("OK"));
 }
 
 /*
@@ -128,15 +217,37 @@ PG_FUNCTION_INFO_V1(dblink_disconnect);
 Datum
 dblink_disconnect(PG_FUNCTION_ARGS)
 {
-	text	   *result_text;
+	char	   *str = NULL;
+	remoteConn *rcon = NULL;
+	PGconn	   *conn = NULL;
+
+	if (PG_NARGS() ==1 )
+	{
+		str = GET_STR(PG_GETARG_TEXT_P(0));
+		rcon = getConnectionByName(str);
+		if (rcon)
+			conn = rcon->con;
+	}
+	else
+		conn = persistent_conn;
 
-	if (persistent_conn != NULL)
-		PQfinish(persistent_conn);
+	if (!conn)
+	{
+		if (str)
+			elog(ERROR,"dblink_disconnect: connection named \"%s\" not found",
+																		 str);
+		else
+			elog(ERROR,"dblink_disconnect: connection not found");
+	}
 
-	persistent_conn = NULL;
+	PQfinish(conn);
+	if (rcon)
+	{
+		deleteConnection(str);
+		pfree(rcon);
+	}
 
-	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum("OK")));
-	PG_RETURN_TEXT_P(result_text);
+	PG_RETURN_TEXT_P(GET_TEXT("OK"));
 }
 
 /*
@@ -149,27 +260,35 @@ dblink_open(PG_FUNCTION_ARGS)
 	char	   *msg;
 	PGresult   *res = NULL;
 	PGconn	   *conn = NULL;
-	text	   *result_text;
-	char	   *curname = GET_STR(PG_GETARG_TEXT_P(0));
-	char	   *sql = GET_STR(PG_GETARG_TEXT_P(1));
+	char	   *curname = NULL;
+	char	   *sql = NULL;
+	char	   *conname = NULL;
 	StringInfo	str = makeStringInfo();
+	remoteConn *rcon = NULL;
 
-	if (persistent_conn != NULL)
+	if(PG_NARGS() == 2)
+	{
+		curname = GET_STR(PG_GETARG_TEXT_P(0));
+		sql = GET_STR(PG_GETARG_TEXT_P(1));
 		conn = persistent_conn;
-	else
-		elog(ERROR, "dblink_open: no connection available");
+	}
+	else if(PG_NARGS() == 3)
+	{
+		conname = GET_STR(PG_GETARG_TEXT_P(0));
+		curname = GET_STR(PG_GETARG_TEXT_P(1));
+		sql = GET_STR(PG_GETARG_TEXT_P(2));
+		rcon = getConnectionByName(conname);
+		if (rcon)
+			conn = rcon->con;
+	}
+
+	if (!conn)
+		DBLINK_CONN_NOT_AVAIL("dblink_open");
 
 	res = PQexec(conn, "BEGIN");
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
-	{
-		msg = pstrdup(PQerrorMessage(conn));
-		PQclear(res);
+		DBLINK_RES_ERROR("dblink_open", "begin error");
 
-		PQfinish(conn);
-		persistent_conn = NULL;
-
-		elog(ERROR, "dblink_open: begin error: %s", msg);
-	}
 	PQclear(res);
 
 	appendStringInfo(str, "DECLARE %s CURSOR FOR %s", curname, sql);
@@ -177,19 +296,11 @@ dblink_open(PG_FUNCTION_ARGS)
 	if (!res ||
 		(PQresultStatus(res) != PGRES_COMMAND_OK &&
 		 PQresultStatus(res) != PGRES_TUPLES_OK))
-	{
-		msg = pstrdup(PQerrorMessage(conn));
-
-		PQclear(res);
-
-		PQfinish(conn);
-		persistent_conn = NULL;
+		DBLINK_RES_ERROR("dblink_open", "sql error");
 
-		elog(ERROR, "dblink: sql error: %s", msg);
-	}
+	PQclear(res);
 
-	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum("OK")));
-	PG_RETURN_TEXT_P(result_text);
+	PG_RETURN_TEXT_P(GET_TEXT("OK"));
 }
 
 /*
@@ -201,49 +312,46 @@ dblink_close(PG_FUNCTION_ARGS)
 {
 	PGconn	   *conn = NULL;
 	PGresult   *res = NULL;
-	char	   *curname = GET_STR(PG_GETARG_TEXT_P(0));
+	char	   *curname = NULL;
+	char	   *conname = NULL;
 	StringInfo	str = makeStringInfo();
-	text	   *result_text;
 	char	   *msg;
+	remoteConn *rcon = NULL;
 
-	if (persistent_conn != NULL)
+	if (PG_NARGS() == 1)
+	{
+		curname = GET_STR(PG_GETARG_TEXT_P(0));
 		conn = persistent_conn;
-	else
-		elog(ERROR, "dblink_close: no connection available");
+	}
+	else if (PG_NARGS()==2)
+	{
+		conname = GET_STR(PG_GETARG_TEXT_P(0));
+		curname = GET_STR(PG_GETARG_TEXT_P(1));
+		rcon = getConnectionByName(conname);
+		if(rcon)
+			conn = rcon->con;
+	}
+
+	if (!conn)
+		DBLINK_CONN_NOT_AVAIL("dblink_close");
 
 	appendStringInfo(str, "CLOSE %s", curname);
 
 	/* close the cursor */
 	res = PQexec(conn, str->data);
 	if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
-	{
-		msg = pstrdup(PQerrorMessage(conn));
-		PQclear(res);
-
-		PQfinish(persistent_conn);
-		persistent_conn = NULL;
-
-		elog(ERROR, "dblink_close: sql error: %s", msg);
-	}
+		DBLINK_RES_ERROR("dblink_close", "sql error");
 
 	PQclear(res);
 
 	/* commit the transaction */
 	res = PQexec(conn, "COMMIT");
 	if (PQresultStatus(res) != PGRES_COMMAND_OK)
-	{
-		msg = pstrdup(PQerrorMessage(conn));
-		PQclear(res);
-
-		PQfinish(persistent_conn);
-		persistent_conn = NULL;
+		DBLINK_RES_ERROR("dblink_close", "commit error");
 
-		elog(ERROR, "dblink_close: commit error: %s", msg);
-	}
 	PQclear(res);
 
-	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum("OK")));
-	PG_RETURN_TEXT_P(result_text);
+	PG_RETURN_TEXT_P(GET_TEXT("OK"));
 }
 
 /*
@@ -262,6 +370,8 @@ dblink_fetch(PG_FUNCTION_ARGS)
 	char	   *msg;
 	PGresult   *res = NULL;
 	MemoryContext oldcontext;
+	char	   *conname = NULL;
+	remoteConn *rcon=NULL;
 
 	/* stuff done only on the first call of the function */
 	if (SRF_IS_FIRSTCALL())
@@ -271,8 +381,28 @@ dblink_fetch(PG_FUNCTION_ARGS)
 		Oid			funcid = fcinfo->flinfo->fn_oid;
 		PGconn	   *conn = NULL;
 		StringInfo	str = makeStringInfo();
-		char	   *curname = GET_STR(PG_GETARG_TEXT_P(0));
-		int			howmany = PG_GETARG_INT32(1);
+		char	   *curname = NULL;
+		int			howmany = 0;
+
+		if (PG_NARGS() == 3)
+		{
+			conname = GET_STR(PG_GETARG_TEXT_P(0));
+			curname = GET_STR(PG_GETARG_TEXT_P(1));
+			howmany = PG_GETARG_INT32(2);
+
+			rcon = getConnectionByName(conname);
+			if(rcon)
+				conn = rcon->con;
+		}
+		else if (PG_NARGS() == 2)
+		{
+			curname = GET_STR(PG_GETARG_TEXT_P(0));
+			howmany = PG_GETARG_INT32(1);
+			conn = persistent_conn;
+		}
+
+		if(!conn)
+			DBLINK_CONN_NOT_AVAIL("dblink_fetch");
 
 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();
@@ -283,11 +413,6 @@ dblink_fetch(PG_FUNCTION_ARGS)
 		 */
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
-		if (persistent_conn != NULL)
-			conn = persistent_conn;
-		else
-			elog(ERROR, "dblink_fetch: no connection available");
-
 		appendStringInfo(str, "FETCH %d FROM %s", howmany, curname);
 
 		res = PQexec(conn, str->data);
@@ -295,19 +420,13 @@ dblink_fetch(PG_FUNCTION_ARGS)
 			(PQresultStatus(res) != PGRES_COMMAND_OK &&
 			 PQresultStatus(res) != PGRES_TUPLES_OK))
 		{
-			msg = pstrdup(PQerrorMessage(conn));
-			PQclear(res);
-
-			PQfinish(persistent_conn);
-			persistent_conn = NULL;
-
-			elog(ERROR, "dblink_fetch: sql error: %s", msg);
+			DBLINK_RES_ERROR("dblink_fetch", "sql error");
 		}
 		else if (PQresultStatus(res) == PGRES_COMMAND_OK)
 		{
 			/* cursor does not exist - closed already or bad name */
 			PQclear(res);
-			elog(ERROR, "dblink_fetch: cursor %s does not exist", curname);
+			elog(ERROR, "dblink_fetch: cursor not found: %s", curname);
 		}
 
 		funcctx->max_calls = PQntuples(res);
@@ -380,8 +499,8 @@ dblink_fetch(PG_FUNCTION_ARGS)
 		SRF_RETURN_NEXT(funcctx, result);
 	}
 	else
-/* do when there is no more left */
 	{
+		/* do when there is no more left */
 		PQclear(res);
 		SRF_RETURN_DONE(funcctx);
 	}
@@ -405,6 +524,7 @@ dblink_record(PG_FUNCTION_ARGS)
 	bool		is_sql_cmd = false;
 	char	   *sql_cmd_status = NULL;
 	MemoryContext oldcontext;
+	bool		freeconn = true;
 
 	/* stuff done only on the first call of the function */
 	if (SRF_IS_FIRSTCALL())
@@ -415,6 +535,8 @@ dblink_record(PG_FUNCTION_ARGS)
 		PGconn	   *conn = NULL;
 		char	   *connstr = NULL;
 		char	   *sql = NULL;
+		char	   *conname = NULL;
+		remoteConn *rcon=NULL;
 
 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();
@@ -425,70 +547,51 @@ dblink_record(PG_FUNCTION_ARGS)
 		 */
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
-		if (fcinfo->nargs == 2)
+		if (PG_NARGS() == 2)
 		{
-			connstr = GET_STR(PG_GETARG_TEXT_P(0));
+			DBLINK_GET_CONN("dblink");
 			sql = GET_STR(PG_GETARG_TEXT_P(1));
-
-			conn = PQconnectdb(connstr);
-			if (PQstatus(conn) == CONNECTION_BAD)
-			{
-				msg = pstrdup(PQerrorMessage(conn));
-				PQfinish(conn);
-				elog(ERROR, "dblink: connection error: %s", msg);
-			}
 		}
-		else if (fcinfo->nargs == 1)
+		else if (PG_NARGS() == 1)
 		{
+			conn = persistent_conn;
 			sql = GET_STR(PG_GETARG_TEXT_P(0));
-
-			if (persistent_conn != NULL)
-				conn = persistent_conn;
-			else
-				elog(ERROR, "dblink: no connection available");
 		}
 		else
 			elog(ERROR, "dblink: wrong number of arguments");
 
+		if(!conn)
+			DBLINK_CONN_NOT_AVAIL("dblink_record");
+
 		res = PQexec(conn, sql);
 		if (!res || (PQresultStatus(res) != PGRES_COMMAND_OK && PQresultStatus(res) != PGRES_TUPLES_OK))
+			DBLINK_RES_ERROR("dblink", "sql error");
+
+		if (PQresultStatus(res) == PGRES_COMMAND_OK)
 		{
-			msg = pstrdup(PQerrorMessage(conn));
-			PQclear(res);
-			PQfinish(conn);
-			if (fcinfo->nargs == 1)
-				persistent_conn = NULL;
+			is_sql_cmd = true;
+
+			/* need a tuple descriptor representing one TEXT column */
+			tupdesc = CreateTemplateTupleDesc(1, false);
+			TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
+							   TEXTOID, -1, 0, false);
 
-			elog(ERROR, "dblink: sql error: %s", msg);
+			/*
+			 * and save a copy of the command status string to return
+			 * as our result tuple
+			 */
+			sql_cmd_status = PQcmdStatus(res);
+			funcctx->max_calls = 1;
 		}
 		else
-		{
-			if (PQresultStatus(res) == PGRES_COMMAND_OK)
-			{
-				is_sql_cmd = true;
-
-				/* need a tuple descriptor representing one TEXT column */
-				tupdesc = CreateTemplateTupleDesc(1, false);
-				TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
-								   TEXTOID, -1, 0, false);
-
-				/*
-				 * and save a copy of the command status string to return
-				 * as our result tuple
-				 */
-				sql_cmd_status = PQcmdStatus(res);
-				funcctx->max_calls = 1;
-			}
-			else
-				funcctx->max_calls = PQntuples(res);
+			funcctx->max_calls = PQntuples(res);
 
-			/* got results, keep track of them */
-			funcctx->user_fctx = res;
+		/* got results, keep track of them */
+		funcctx->user_fctx = res;
 
-			/* if needed, close the connection to the database and cleanup */
-			if (fcinfo->nargs == 2)
-				PQfinish(conn);
-		}
+		/* if needed, close the connection to the database and cleanup */
+		if (freeconn && PG_NARGS() == 2)
+			PQfinish(conn);
 
 		/* fast track when no results */
 		if (funcctx->max_calls < 1)
@@ -567,8 +670,8 @@ dblink_record(PG_FUNCTION_ARGS)
 		SRF_RETURN_NEXT(funcctx, result);
 	}
 	else
-/* do when there is no more left */
 	{
+		/* do when there is no more left */
 		PQclear(res);
 		SRF_RETURN_DONE(funcctx);
 	}
@@ -583,272 +686,62 @@ dblink_exec(PG_FUNCTION_ARGS)
 {
 	char	   *msg;
 	PGresult   *res = NULL;
-	char	   *sql_cmd_status = NULL;
+	text	   *sql_cmd_status = NULL;
 	TupleDesc	tupdesc = NULL;
-	text	   *result_text;
 	PGconn	   *conn = NULL;
 	char	   *connstr = NULL;
 	char	   *sql = NULL;
+	char	   *conname = NULL;
+	remoteConn *rcon=NULL;
+	bool		freeconn = true;
 
-	if (fcinfo->nargs == 2)
+	if (PG_NARGS() == 2)
 	{
-		connstr = GET_STR(PG_GETARG_TEXT_P(0));
+		DBLINK_GET_CONN("dblink_exec");
 		sql = GET_STR(PG_GETARG_TEXT_P(1));
-
-		conn = PQconnectdb(connstr);
-		if (PQstatus(conn) == CONNECTION_BAD)
-		{
-			msg = pstrdup(PQerrorMessage(conn));
-			PQfinish(conn);
-			elog(ERROR, "dblink_exec: connection error: %s", msg);
-		}
 	}
-	else if (fcinfo->nargs == 1)
+	else if (PG_NARGS() == 1)
 	{
+		conn = persistent_conn;
 		sql = GET_STR(PG_GETARG_TEXT_P(0));
-
-		if (persistent_conn != NULL)
-			conn = persistent_conn;
-		else
-			elog(ERROR, "dblink_exec: no connection available");
 	}
 	else
 		elog(ERROR, "dblink_exec: wrong number of arguments");
 
+	if(!conn)
+		DBLINK_CONN_NOT_AVAIL("dblink_exec");
 
 	res = PQexec(conn, sql);
-	if (!res || (PQresultStatus(res) != PGRES_COMMAND_OK && PQresultStatus(res) != PGRES_TUPLES_OK))
+	if (!res ||
+		(PQresultStatus(res) != PGRES_COMMAND_OK &&
+		 PQresultStatus(res) != PGRES_TUPLES_OK))
+		DBLINK_RES_ERROR("dblink_exec", "sql error");
+
+	if (PQresultStatus(res) == PGRES_COMMAND_OK)
 	{
-		msg = pstrdup(PQerrorMessage(conn));
-		PQclear(res);
-		PQfinish(conn);
-		if (fcinfo->nargs == 1)
-			persistent_conn = NULL;
+		/* need a tuple descriptor representing one TEXT column */
+		tupdesc = CreateTemplateTupleDesc(1, false);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
+						   TEXTOID, -1, 0, false);
 
-		elog(ERROR, "dblink_exec: sql error: %s", msg);
+		/*
+		 * and save a copy of the command status string to return as
+		 * our result tuple
+		 */
+		sql_cmd_status = GET_TEXT(PQcmdStatus(res));
 	}
 	else
-	{
-		if (PQresultStatus(res) == PGRES_COMMAND_OK)
-		{
-			/* need a tuple descriptor representing one TEXT column */
-			tupdesc = CreateTemplateTupleDesc(1, false);
-			TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
-							   TEXTOID, -1, 0, false);
+		elog(ERROR, "dblink_exec: queries returning results not allowed");
 
-			/*
-			 * and save a copy of the command status string to return as
-			 * our result tuple
-			 */
-			sql_cmd_status = PQcmdStatus(res);
-		}
-		else
-			elog(ERROR, "dblink_exec: queries returning results not allowed");
-	}
 	PQclear(res);
 
 	/* if needed, close the connection to the database and cleanup */
-	if (fcinfo->nargs == 2)
+	if (freeconn && fcinfo->nargs == 2)
 		PQfinish(conn);
 
-	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(sql_cmd_status)));
-	PG_RETURN_TEXT_P(result_text);
+	PG_RETURN_TEXT_P(sql_cmd_status);
 }
 
-/*
- * Note: this original version of dblink is DEPRECATED;
- * it *will* be removed in favor of the new version on next release
- */
-PG_FUNCTION_INFO_V1(dblink);
-Datum
-dblink(PG_FUNCTION_ARGS)
-{
-	PGconn	   *conn = NULL;
-	PGresult   *res = NULL;
-	dblink_results *results;
-	char	   *optstr;
-	char	   *sqlstatement;
-	char	   *execstatement;
-	char	   *msg;
-	int			ntuples = 0;
-	ReturnSetInfo *rsi;
-
-	if (fcinfo->resultinfo == NULL || !IsA(fcinfo->resultinfo, ReturnSetInfo))
-		elog(ERROR, "dblink: function called in context that does not accept a set result");
-
-	optstr = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(0))));
-	sqlstatement = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(PG_GETARG_TEXT_P(1))));
-
-	if (fcinfo->flinfo->fn_extra == NULL)
-	{
-
-		conn = PQconnectdb(optstr);
-		if (PQstatus(conn) == CONNECTION_BAD)
-		{
-			msg = pstrdup(PQerrorMessage(conn));
-			PQfinish(conn);
-			elog(ERROR, "dblink: connection error: %s", msg);
-		}
-
-		execstatement = (char *) palloc(strlen(sqlstatement) + 1);
-		if (execstatement != NULL)
-		{
-			strcpy(execstatement, sqlstatement);
-			strcat(execstatement, "\0");
-		}
-		else
-			elog(ERROR, "dblink: insufficient memory");
-
-		res = PQexec(conn, execstatement);
-		if (!res || (PQresultStatus(res) != PGRES_COMMAND_OK && PQresultStatus(res) != PGRES_TUPLES_OK))
-		{
-			msg = pstrdup(PQerrorMessage(conn));
-			PQclear(res);
-			PQfinish(conn);
-			elog(ERROR, "dblink: sql error: %s", msg);
-		}
-		else
-		{
-			/*
-			 * got results, start fetching them
-			 */
-			ntuples = PQntuples(res);
-
-			/*
-			 * increment resource index
-			 */
-			res_id_index++;
-
-			results = init_dblink_results(fcinfo->flinfo->fn_mcxt);
-			results->tup_num = 0;
-			results->res_id_index = res_id_index;
-			results->res = res;
-
-			/*
-			 * Append node to res_id to hold pointer to results. Needed by
-			 * dblink_tok to access the data
-			 */
-			append_res_ptr(results);
-
-			/*
-			 * save pointer to results for the next function manager call
-			 */
-			fcinfo->flinfo->fn_extra = (void *) results;
-
-			/* close the connection to the database and cleanup */
-			PQfinish(conn);
-
-			rsi = (ReturnSetInfo *) fcinfo->resultinfo;
-			rsi->isDone = ExprMultipleResult;
-
-			PG_RETURN_INT32(res_id_index);
-		}
-	}
-	else
-	{
-		/*
-		 * check for more results
-		 */
-		results = fcinfo->flinfo->fn_extra;
-
-		results->tup_num++;
-		res_id_index = results->res_id_index;
-		ntuples = PQntuples(results->res);
-
-		if (results->tup_num < ntuples)
-		{
-			/*
-			 * fetch them if available
-			 */
-
-			rsi = (ReturnSetInfo *) fcinfo->resultinfo;
-			rsi->isDone = ExprMultipleResult;
-
-			PG_RETURN_INT32(res_id_index);
-		}
-		else
-		{
-			/*
-			 * or if no more, clean things up
-			 */
-			results = fcinfo->flinfo->fn_extra;
-
-			remove_res_ptr(results);
-			PQclear(results->res);
-			pfree(results);
-			fcinfo->flinfo->fn_extra = NULL;
-
-			rsi = (ReturnSetInfo *) fcinfo->resultinfo;
-			rsi->isDone = ExprEndResult;
-
-			PG_RETURN_NULL();
-		}
-	}
-	PG_RETURN_NULL();
-}
-
-/*
- * Note: dblink_tok is DEPRECATED;
- * it *will* be removed in favor of the new version on next release
- *
- * dblink_tok
- * parse dblink output string
- * return fldnum item (0 based)
- * based on provided field separator
- */
-PG_FUNCTION_INFO_V1(dblink_tok);
-Datum
-dblink_tok(PG_FUNCTION_ARGS)
-{
-	dblink_results *results;
-	int			fldnum;
-	text	   *result_text;
-	char	   *result;
-	int			nfields = 0;
-	int			text_len = 0;
-
-	results = get_res_ptr(PG_GETARG_INT32(0));
-	if (results == NULL)
-	{
-		if (res_id != NIL)
-		{
-			freeList(res_id);
-			res_id = NIL;
-			res_id_index = 0;
-		}
-
-		elog(ERROR, "dblink_tok: function called with invalid resource id");
-	}
-
-	fldnum = PG_GETARG_INT32(1);
-	if (fldnum < 0)
-		elog(ERROR, "dblink_tok: field number < 0 not permitted");
-
-	nfields = PQnfields(results->res);
-	if (fldnum > (nfields - 1))
-		elog(ERROR, "dblink_tok: field number %d does not exist", fldnum);
-
-	if (PQgetisnull(results->res, results->tup_num, fldnum) == 1)
-		PG_RETURN_NULL();
-	else
-	{
-		text_len = PQgetlength(results->res, results->tup_num, fldnum);
-
-		result = (char *) palloc(text_len + 1);
-
-		if (result != NULL)
-		{
-			strcpy(result, PQgetvalue(results->res, results->tup_num, fldnum));
-			strcat(result, "\0");
-		}
-		else
-			elog(ERROR, "dblink: insufficient memory");
-
-		result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(result)));
-
-		PG_RETURN_TEXT_P(result_text);
-	}
-}
 
 /*
  * dblink_get_pkey
@@ -923,7 +816,7 @@ dblink_get_pkey(PG_FUNCTION_ARGS)
 			funcctx->user_fctx = results;
 		}
 		else
-/* fast track when no results */
+			/* fast track when no results */
 			SRF_RETURN_DONE(funcctx);
 
 		MemoryContextSwitchTo(oldcontext);
@@ -965,37 +858,10 @@ dblink_get_pkey(PG_FUNCTION_ARGS)
 		SRF_RETURN_NEXT(funcctx, result);
 	}
 	else
-/* do when there is no more left */
-		SRF_RETURN_DONE(funcctx);
-}
-
-/*
- * Note: dblink_last_oid is DEPRECATED;
- * it *will* be removed on next release
- *
- * dblink_last_oid
- * return last inserted oid
- */
-PG_FUNCTION_INFO_V1(dblink_last_oid);
-Datum
-dblink_last_oid(PG_FUNCTION_ARGS)
-{
-	dblink_results *results;
-
-	results = get_res_ptr(PG_GETARG_INT32(0));
-	if (results == NULL)
 	{
-		if (res_id != NIL)
-		{
-			freeList(res_id);
-			res_id = NIL;
-			res_id_index = 0;
-		}
-
-		elog(ERROR, "dblink_tok: function called with invalid resource id");
+		/* do when there is no more left */
+		SRF_RETURN_DONE(funcctx);
 	}
-
-	PG_RETURN_OID(PQoidValue(results->res));
 }
 
 
@@ -1043,7 +909,6 @@ dblink_build_sql_insert(PG_FUNCTION_ARGS)
 	int			i;
 	char	   *ptr;
 	char	   *sql;
-	text	   *sql_text;
 	int16		typlen;
 	bool		typbyval;
 	char		typalign;
@@ -1138,15 +1003,10 @@ dblink_build_sql_insert(PG_FUNCTION_ARGS)
 	 */
 	sql = get_sql_insert(relid, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
 
-	/*
-	 * Make it into TEXT for return to the client
-	 */
-	sql_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(sql)));
-
 	/*
 	 * And send it
 	 */
-	PG_RETURN_TEXT_P(sql_text);
+	PG_RETURN_TEXT_P(GET_TEXT(sql));
 }
 
 
@@ -1182,7 +1042,6 @@ dblink_build_sql_delete(PG_FUNCTION_ARGS)
 	int			i;
 	char	   *ptr;
 	char	   *sql;
-	text	   *sql_text;
 	int16		typlen;
 	bool		typbyval;
 	char		typalign;
@@ -1246,15 +1105,10 @@ dblink_build_sql_delete(PG_FUNCTION_ARGS)
 	 */
 	sql = get_sql_delete(relid, pkattnums, pknumatts, tgt_pkattvals);
 
-	/*
-	 * Make it into TEXT for return to the client
-	 */
-	sql_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(sql)));
-
 	/*
 	 * And send it
 	 */
-	PG_RETURN_TEXT_P(sql_text);
+	PG_RETURN_TEXT_P(GET_TEXT(sql));
 }
 
 
@@ -1299,7 +1153,6 @@ dblink_build_sql_update(PG_FUNCTION_ARGS)
 	int			i;
 	char	   *ptr;
 	char	   *sql;
-	text	   *sql_text;
 	int16		typlen;
 	bool		typbyval;
 	char		typalign;
@@ -1394,15 +1247,10 @@ dblink_build_sql_update(PG_FUNCTION_ARGS)
 	 */
 	sql = get_sql_update(relid, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
 
-	/*
-	 * Make it into TEXT for return to the client
-	 */
-	sql_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(sql)));
-
 	/*
 	 * And send it
 	 */
-	PG_RETURN_TEXT_P(sql_text);
+	PG_RETURN_TEXT_P(GET_TEXT(sql));
 }
 
 /*
@@ -1415,10 +1263,7 @@ PG_FUNCTION_INFO_V1(dblink_current_query);
 Datum
 dblink_current_query(PG_FUNCTION_ARGS)
 {
-	text	   *result_text;
-
-	result_text = DatumGetTextP(DirectFunctionCall1(textin, CStringGetDatum(debug_query_string)));
-	PG_RETURN_TEXT_P(result_text);
+	PG_RETURN_TEXT_P(GET_TEXT(debug_query_string));
 }
 
 
@@ -1427,29 +1272,6 @@ dblink_current_query(PG_FUNCTION_ARGS)
  */
 
 
-/*
- * init_dblink_results
- *	 - create an empty dblink_results data structure
- */
-static dblink_results *
-init_dblink_results(MemoryContext fn_mcxt)
-{
-	MemoryContext oldcontext;
-	dblink_results *retval;
-
-	oldcontext = MemoryContextSwitchTo(fn_mcxt);
-
-	retval = (dblink_results *) palloc0(sizeof(dblink_results));
-
-	retval->tup_num = -1;
-	retval->res_id_index = -1;
-	retval->res = NULL;
-
-	MemoryContextSwitchTo(oldcontext);
-
-	return retval;
-}
-
 /*
  * get_pkey_attnames
  *
@@ -1488,7 +1310,10 @@ get_pkey_attnames(Oid relid, int16 *numatts)
 		/* we're only interested if it is the primary key */
 		if (index->indisprimary == TRUE)
 		{
-			*numatts = index->indnatts;
+			i = 0;
+			while (index->indkey[i++] != 0)
+				(*numatts)++;
+
 			if (*numatts > 0)
 			{
 				result = (char **) palloc(*numatts * sizeof(char *));
@@ -1907,52 +1732,6 @@ get_relid_from_relname(text *relname_text)
 	return relid;
 }
 
-static dblink_results *
-get_res_ptr(int32 res_id_index)
-{
-	List	   *ptr;
-
-	/*
-	 * short circuit empty list
-	 */
-	if (res_id == NIL)
-		return NULL;
-
-	/*
-	 * OK, should be good to go
-	 */
-	foreach(ptr, res_id)
-	{
-		dblink_results *this_res_id = (dblink_results *) lfirst(ptr);
-
-		if (this_res_id->res_id_index == res_id_index)
-			return this_res_id;
-	}
-	return NULL;
-}
-
-/*
- * Add node to global List res_id
- */
-static void
-append_res_ptr(dblink_results * results)
-{
-	res_id = lappend(res_id, results);
-}
-
-/*
- * Remove node from global List
- * using res_id_index
- */
-static void
-remove_res_ptr(dblink_results * results)
-{
-	res_id = lremove(results, res_id);
-
-	if (res_id == NIL)
-		res_id_index = 0;
-}
-
 static TupleDesc
 pgresultGetTupleDesc(PGresult *res)
 {
@@ -2039,3 +1818,91 @@ generate_relation_name(Oid relid)
 
 	return result;
 }
+
+
+static remoteConn *
+getConnectionByName(const char *name)
+{
+	remoteConnHashEnt  *hentry;
+	char				key[NAMEDATALEN];
+
+	if(!remoteConnHash)
+		remoteConnHash=createConnHash();
+
+	MemSet(key, 0, NAMEDATALEN);
+	snprintf(key, NAMEDATALEN - 1, "%s", name);
+	hentry = (remoteConnHashEnt*) hash_search(remoteConnHash,
+											  key, HASH_FIND, NULL);
+
+	if(hentry)
+		return(hentry->rcon);
+
+	return(NULL);
+}
+
+static HTAB *
+createConnHash(void)
+{
+	HASHCTL	ctl;
+	HTAB   *ptr;
+
+	ctl.keysize = NAMEDATALEN;
+	ctl.entrysize = sizeof(remoteConnHashEnt);
+
+	ptr=hash_create("Remote Con hash", NUMCONN, &ctl, HASH_ELEM);
+
+	if(!ptr)
+		elog(ERROR,"Can not create connections hash table. Out of memory");
+
+	return(ptr);
+}
+
+static bool
+createNewConnection(const char *name, remoteConn *con)
+{
+	remoteConnHashEnt  *hentry;
+	bool				found;
+	char				key[NAMEDATALEN];
+
+	if(!remoteConnHash)
+		remoteConnHash=createConnHash();
+
+	MemSet(key, 0, NAMEDATALEN);
+	snprintf(key, NAMEDATALEN - 1, "%s", name);
+	hentry = (remoteConnHashEnt *) hash_search(remoteConnHash, key,
+											   HASH_ENTER, &found);
+
+	if(!hentry)
+		elog(ERROR, "failed to create connection");
+
+	if(found)
+	{
+		elog(NOTICE, "cannot use a connection name more than once");
+		return false;
+	}
+
+	hentry->rcon = con;
+	strncpy(hentry->name, name, NAMEDATALEN - 1);
+
+	return true;
+}
+
+static void
+deleteConnection(const char *name)
+{
+	remoteConnHashEnt  *hentry;
+	bool				found;
+	char				key[NAMEDATALEN];
+
+	if(!remoteConnHash)
+		remoteConnHash=createConnHash();
+
+	MemSet(key, 0, NAMEDATALEN);
+	snprintf(key, NAMEDATALEN - 1, "%s", name);
+
+	hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
+											   key, HASH_REMOVE, &found);
+
+	if(!hentry)
+		elog(WARNING,"Trying to delete a connection that does not exist");
+}

contrib/dblink/dblink.h

@@ -4,8 +4,11 @@
  * Functions returning results from a remote database
  *
  * Joe Conway <mail@joeconway.com>
+ * And contributors:
+ * Darko Prenosil <Darko.Prenosil@finteh.hr>
+ * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
  *
- * Copyright (c) 2001, 2002 by PostgreSQL Global Development Group
+ * Copyright (c) 2001, 2002, 2003 by PostgreSQL Global Development Group
  * ALL RIGHTS RESERVED;
  *
  * Permission to use, copy, modify, and distribute this software and its
@@ -30,36 +33,9 @@
 #ifndef DBLINK_H
 #define DBLINK_H
 
-/*
- * This struct holds the results of the remote query.
- * Use fn_extra to hold a pointer to it across calls
- */
-typedef struct
-{
-	/*
-	 * last tuple number accessed
-	 */
-	int			tup_num;
-
-	/*
-	 * resource index number for this context
-	 */
-	int			res_id_index;
-
-	/*
-	 * the actual query results
-	 */
-	PGresult   *res;
-}	dblink_results;
-
 /*
  * External declarations
  */
-/* deprecated */
-extern Datum dblink(PG_FUNCTION_ARGS);
-extern Datum dblink_tok(PG_FUNCTION_ARGS);
-
-/* supported */
 extern Datum dblink_connect(PG_FUNCTION_ARGS);
 extern Datum dblink_disconnect(PG_FUNCTION_ARGS);
 extern Datum dblink_open(PG_FUNCTION_ARGS);
@@ -68,7 +44,6 @@ extern Datum dblink_fetch(PG_FUNCTION_ARGS);
 extern Datum dblink_record(PG_FUNCTION_ARGS);
 extern Datum dblink_exec(PG_FUNCTION_ARGS);
 extern Datum dblink_get_pkey(PG_FUNCTION_ARGS);
-extern Datum dblink_last_oid(PG_FUNCTION_ARGS);
 extern Datum dblink_build_sql_insert(PG_FUNCTION_ARGS);
 extern Datum dblink_build_sql_delete(PG_FUNCTION_ARGS);
 extern Datum dblink_build_sql_update(PG_FUNCTION_ARGS);

contrib/dblink/dblink.sql.in

---
--- Uncomment the following commented lines to use original DEPRECATED functions
---
---CREATE OR REPLACE FUNCTION dblink (text,text)
---RETURNS setof int
---AS 'MODULE_PATHNAME','dblink'
---LANGUAGE 'C' WITH (isstrict);
---CREATE OR REPLACE FUNCTION dblink_tok (int,int)
---RETURNS text
---AS 'MODULE_PATHNAME','dblink_tok'
---LANGUAGE 'C' WITH (isstrict);
---CREATE OR REPLACE FUNCTION dblink_last_oid (int)
---RETURNS oid
---AS 'MODULE_PATHNAME','dblink_last_oid'
---LANGUAGE 'C' WITH (isstrict);
-
 CREATE OR REPLACE FUNCTION dblink_connect (text)
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_connect'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_connect (text, text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_connect'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_disconnect ()
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_disconnect'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_disconnect (text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_disconnect'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_open (text,text)
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_open'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_open (text,text,text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_open'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_fetch (text,int)
 RETURNS setof record
 AS 'MODULE_PATHNAME','dblink_fetch'
 LANGUAGE 'C' WITH (isstrict);
 
+CREATE OR REPLACE FUNCTION dblink_fetch (text,text,int)
+RETURNS setof record
+AS 'MODULE_PATHNAME','dblink_fetch'
+LANGUAGE 'C' WITH (isstrict);
+
 CREATE OR REPLACE FUNCTION dblink_close (text)
 RETURNS text
 AS 'MODULE_PATHNAME','dblink_close'
 LANGUAGE 'C' WITH (isstrict);
 
--- Note: if this is not a first time install of dblink, uncomment the
--- following DROP which prepares the database for the new, non-deprecated
--- version.
---DROP FUNCTION dblink (text,text);
+CREATE OR REPLACE FUNCTION dblink_close (text,text)
+RETURNS text
+AS 'MODULE_PATHNAME','dblink_close'
+LANGUAGE 'C' WITH (isstrict);
 
--- Comment out the following 3 lines if the DEPRECATED functions are used.
 CREATE OR REPLACE FUNCTION dblink (text,text)
 RETURNS setof record
 AS 'MODULE_PATHNAME','dblink_record'

contrib/dblink/doc/connection

@@ -6,21 +6,35 @@ dblink_connect -- Opens a persistent connection to a remote database
 Synopsis
 
 dblink_connect(text connstr)
+dblink_connect(text connname, text connstr)
 
 Inputs
 
+  connname
+    if 2 arguments are given, the first is used as a name for a persistent
+    connection
+
   connstr
 
     standard libpq format connection string, 
     e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
 
+    if only one argument is given, the connection is unnamed; only one unnamed
+    connection can exist at a time
+
 Outputs
 
   Returns status = "OK"
 
 Example usage
 
-test=# select dblink_connect('dbname=template1');
+select dblink_connect('dbname=template1');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select dblink_connect('myconn','dbname=template1');
  dblink_connect
 ----------------
  OK
@@ -29,15 +43,18 @@ test=# select dblink_connect('dbname=template1');
 ==================================================================
 Name
 
-dblink_disconnect -- Closes the persistent connection to a remote database
+dblink_disconnect -- Closes a persistent connection to a remote database
 
 Synopsis
 
 dblink_disconnect()
+dblink_disconnect(text connname)
 
 Inputs
 
-  none
+  connname
+    if an argument is given, it is used as a name for a persistent
+    connection to close; otherwiase the unnamed connection is closed
 
 Outputs
 
@@ -51,3 +68,8 @@ test=# select dblink_disconnect();
  OK
 (1 row)
 
+select dblink_disconnect('myconn');
+ dblink_disconnect
+-------------------
+ OK
+(1 row)

contrib/dblink/doc/cursor

@@ -6,9 +6,14 @@ dblink_open -- Opens a cursor on a remote database
 Synopsis
 
 dblink_open(text cursorname, text sql)
+dblink_open(text connname, text cursorname, text sql)
 
 Inputs
 
+  connname
+    if three arguments are present, the first is taken as the specific
+    connection name to use; otherwise the unnamed connection is assumed
+
   cursorname
 
     a reference name for the cursor
@@ -52,9 +57,14 @@ dblink_fetch -- Returns a set from an open cursor on a remote database
 Synopsis
 
 dblink_fetch(text cursorname, int32 howmany)
+dblink_fetch(text connname, text cursorname, int32 howmany)
 
 Inputs
 
+  connname
+    if three arguments are present, the first is taken as the specific
+    connection name to use; otherwise the unnamed connection is assumed
+
   cursorname
 
     The reference name for the cursor
@@ -123,9 +133,14 @@ dblink_close -- Closes a cursor on a remote database
 Synopsis
 
 dblink_close(text cursorname)
+dblink_close(text connname, text cursorname)
 
 Inputs
 
+  connname
+    if two arguments are present, the first is taken as the specific
+    connection name to use; otherwise the unnamed connection is assumed
+
   cursorname
 
     a reference name for the cursor
@@ -135,7 +150,8 @@ Outputs
   Returns status = "OK"
 
 Note
-  dblink_connect(text connstr) must be executed first.
+  dblink_connect(text connstr) or dblink_connect(text connname, text connstr)
+  must be executed first.
 
 Example usage
 
@@ -157,3 +173,20 @@ test=# select dblink_close('foo');
  OK
 (1 row)
 
+select dblink_connect('myconn','dbname=regression');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select dblink_open('myconn','foo','select proname, prosrc from pg_proc');
+ dblink_open
+-------------
+ OK
+(1 row)
+
+select dblink_close('myconn','foo');
+ dblink_close
+--------------
+ OK
+(1 row)

contrib/dblink/doc/execute

@@ -6,22 +6,23 @@ dblink_exec -- Executes an UPDATE/INSERT/DELETE on a remote database
 Synopsis
 
 dblink_exec(text connstr, text sql)
-- or -
+dblink_exec(text connname, text sql)
 dblink_exec(text sql)
 
 Inputs
 
+  connname
   connstr
+    If two arguments are present, the first is first assumed to be a specific
+    connection name to use. If the name is not found, the argument is then
+    assumed to be a valid connection string, of standard libpq format,
+    e.g.: "hostaddr=127.0.0.1 dbname=mydb user=postgres password=mypasswd"
 
-    standard libpq format connection string, 
-    e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
-    If the second form is used, then the dblink_connect(text connstr) must be
-    executed first.
+    If only one argument is used, then the unnamed connection is used.
 
   sql
 
     sql statement that you wish to execute on the remote host, e.g.:
-
        insert into foo values(0,'a','{"a0","b0","c0"}');
 
 Outputs
@@ -36,14 +37,26 @@ Notes
 
 Example usage
 
-test=# select dblink_connect('dbname=dblink_test_slave');
+select dblink_connect('dbname=dblink_test_slave');
  dblink_connect
 ----------------
  OK
 (1 row)
 
-test=# select dblink_exec('insert into foo values(21,''z'',''{"a0","b0","c0"}'');');
+select dblink_exec('insert into foo values(21,''z'',''{"a0","b0","c0"}'');');
    dblink_exec
 -----------------
  INSERT 943366 1
 (1 row)
+
+select dblink_connect('myconn','dbname=regression');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select dblink_exec('myconn','insert into foo values(21,''z'',''{"a0","b0","c0"}'');');
+   dblink_exec
+------------------
+ INSERT 6432584 1
+(1 row)

contrib/dblink/doc/query

@@ -6,17 +6,19 @@ dblink -- Returns a set from a remote database
 Synopsis
 
 dblink(text connstr, text sql)
-- or -
+dblink(text connname, text sql)
 dblink(text sql)
 
 Inputs
 
+  connname
   connstr
+    If two arguments are present, the first is first assumed to be a specific
+    connection name to use. If the name is not found, the argument is then
+    assumed to be a valid connection string, of standard libpq format,
+    e.g.: "hostaddr=127.0.0.1 dbname=mydb user=postgres password=mypasswd"
 
-    standard libpq format connection string, 
-    e.g. "hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres password=mypasswd"
-    If the second form is used, then the dblink_connect(text connstr) must be
-    executed first.
+    If only one argument is used, then the unnamed connection is used.
 
   sql
 
@@ -29,7 +31,7 @@ Outputs
 
 Example usage
 
-test=# select * from dblink('dbname=template1','select proname, prosrc from pg_proc')
+select * from dblink('dbname=template1','select proname, prosrc from pg_proc')
  as t1(proname name, prosrc text) where proname like 'bytea%';
   proname   |   prosrc
 ------------+------------
@@ -47,13 +49,13 @@ test=# select * from dblink('dbname=template1','select proname, prosrc from pg_p
  byteaout   | byteaout
 (12 rows)
 
-test=# select dblink_connect('dbname=template1');
+select dblink_connect('dbname=template1');
  dblink_connect
 ----------------
  OK
 (1 row)
 
-test=# select * from dblink('select proname, prosrc from pg_proc')
+select * from dblink('select proname, prosrc from pg_proc')
  as t1(proname name, prosrc text) where proname like 'bytea%';
   proname   |   prosrc
 ------------+------------
@@ -71,6 +73,33 @@ test=# select * from dblink('select proname, prosrc from pg_proc')
  byteaout   | byteaout
 (12 rows)
 
+select dblink_connect('myconn','dbname=regression');
+ dblink_connect
+----------------
+ OK
+(1 row)
+
+select * from dblink('myconn','select proname, prosrc from pg_proc')
+ as t1(proname name, prosrc text) where proname like 'bytea%';
+  proname   |   prosrc
+------------+------------
+ bytearecv  | bytearecv
+ byteasend  | byteasend
+ byteale    | byteale
+ byteagt    | byteagt
+ byteage    | byteage
+ byteane    | byteane
+ byteacmp   | byteacmp
+ bytealike  | bytealike
+ byteanlike | byteanlike
+ byteacat   | byteacat
+ byteaeq    | byteaeq
+ bytealt    | bytealt
+ byteain    | byteain
+ byteaout   | byteaout
+(14 rows)
+
+
 ==================================================================
 A more convenient way to use dblink may be to create a view:
 

contrib/dblink/expected/dblink.out

@@ -106,11 +106,11 @@ WHERE t.a > 7;
  9 | j | {a9,b9,c9}
 (2 rows)
 
--- should generate "no connection available" error
+-- should generate "connection not available" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
-ERROR:  dblink: no connection available
+ERROR:  dblink_record: connection not available
 -- create a persistent connection
 SELECT dblink_connect('dbname=regression');
  dblink_connect 
@@ -172,10 +172,10 @@ SELECT dblink_close('rmt_foo_cursor');
  OK
 (1 row)
 
--- should generate "cursor rmt_foo_cursor does not exist" error
+-- should generate "cursor not found: rmt_foo_cursor" error
 SELECT *
 FROM dblink_fetch('rmt_foo_cursor',4) AS t(a int, b text, c text[]);
-ERROR:  dblink_fetch: cursor rmt_foo_cursor does not exist
+ERROR:  dblink_fetch: cursor not found: rmt_foo_cursor
 -- close the persistent connection
 SELECT dblink_disconnect();
  dblink_disconnect 
@@ -183,11 +183,12 @@ SELECT dblink_disconnect();
  OK
 (1 row)
 
--- should generate "no connection available" error
+-- should generate "no connection to the server" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
-ERROR:  dblink: no connection available
+ERROR:  dblink: sql error: no connection to the server
+
 -- put more data into our slave table, first using arbitrary connection syntax
 -- but truncate the actual return value so we can use diff to check for success
 SELECT substr(dblink_exec('dbname=regression','INSERT INTO foo VALUES(10,''k'',''{"a10","b10","c10"}'')'),1,6);
@@ -268,3 +269,198 @@ SELECT dblink_disconnect();
  OK
 (1 row)
 
+--
+-- tests for the new named persistent connection syntax
+--
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ERROR:  dblink: connection error: missing "=" after "myconn" in connection info string
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- use the named persistent connection
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ a  | b |       c       
+----+---+---------------
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+(3 rows)
+
+-- create a second named persistent connection
+-- should error with "cannot save named connection"
+SELECT dblink_connect('myconn','dbname=regression');
+NOTICE:  cannot use a connection name more than once
+ERROR:  dblink_connect: cannot save named connection
+-- create a second named persistent connection with a new name
+SELECT dblink_connect('myconn2','dbname=regression');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- use the second named persistent connection
+SELECT *
+FROM dblink('myconn2','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ a  | b |       c       
+----+---+---------------
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+(3 rows)
+
+-- close the second named persistent connection
+SELECT dblink_disconnect('myconn2');
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- open a cursor
+SELECT dblink_open('myconn','rmt_foo_cursor','SELECT * FROM foo');
+ dblink_open 
+-------------
+ OK
+(1 row)
+
+-- fetch some data
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ a | b |     c      
+---+---+------------
+ 0 | a | {a0,b0,c0}
+ 1 | b | {a1,b1,c1}
+ 2 | c | {a2,b2,c2}
+ 3 | d | {a3,b3,c3}
+(4 rows)
+
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ a | b |     c      
+---+---+------------
+ 4 | e | {a4,b4,c4}
+ 5 | f | {a5,b5,c5}
+ 6 | g | {a6,b6,c6}
+ 7 | h | {a7,b7,c7}
+(4 rows)
+
+-- this one only finds three rows left
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ a  | b |       c       
+----+---+---------------
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+(3 rows)
+
+-- close the cursor
+SELECT dblink_close('myconn','rmt_foo_cursor');
+ dblink_close 
+--------------
+ OK
+(1 row)
+
+-- should generate "cursor not found: rmt_foo_cursor" error
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+ERROR:  dblink_fetch: cursor not found: rmt_foo_cursor
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+ERROR:  dblink: connection error: missing "=" after "myconn" in connection info string
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+ dblink_connect 
+----------------
+ OK
+(1 row)
+
+-- put more data into our slave table, using named persistent connection syntax
+-- but truncate the actual return value so we can use diff to check for success
+SELECT substr(dblink_exec('myconn','INSERT INTO foo VALUES(11,''l'',''{"a11","b11","c11"}'')'),1,6);
+ substr 
+--------
+ INSERT
+(1 row)
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]);
+ a  | b |       c       
+----+---+---------------
+  0 | a | {a0,b0,c0}
+  1 | b | {a1,b1,c1}
+  2 | c | {a2,b2,c2}
+  3 | d | {a3,b3,c3}
+  4 | e | {a4,b4,c4}
+  5 | f | {a5,b5,c5}
+  6 | g | {a6,b6,c6}
+  7 | h | {a7,b7,c7}
+  8 | i | {a8,b8,c8}
+  9 | j | {a9,b9,c9}
+ 10 | k | {a10,b10,c10}
+ 11 | l | {a11,b11,c11}
+(12 rows)
+
+-- change some data
+SELECT dblink_exec('myconn','UPDATE foo SET f3[2] = ''b99'' WHERE f1 = 11');
+ dblink_exec 
+-------------
+ UPDATE 1
+(1 row)
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+ a  | b |       c       
+----+---+---------------
+ 11 | l | {a11,b99,c11}
+(1 row)
+
+-- delete some data
+SELECT dblink_exec('myconn','DELETE FROM foo WHERE f1 = 11');
+ dblink_exec 
+-------------
+ DELETE 1
+(1 row)
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+ a | b | c 
+---+---+---
+(0 rows)
+
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+ dblink_disconnect 
+-------------------
+ OK
+(1 row)
+
+-- close the named persistent connection again
+-- should get "connection named "myconn" not found" error
+SELECT dblink_disconnect('myconn');
+ERROR:  dblink_disconnect: connection named "myconn" not found

contrib/dblink/sql/dblink.sql

@@ -68,7 +68,7 @@ SELECT *
 FROM dblink('dbname=regression','SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
 
--- should generate "no connection available" error
+-- should generate "connection not available" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
@@ -98,14 +98,14 @@ FROM dblink_fetch('rmt_foo_cursor',4) AS t(a int, b text, c text[]);
 -- close the cursor
 SELECT dblink_close('rmt_foo_cursor');
 
--- should generate "cursor rmt_foo_cursor does not exist" error
+-- should generate "cursor not found: rmt_foo_cursor" error
 SELECT *
 FROM dblink_fetch('rmt_foo_cursor',4) AS t(a int, b text, c text[]);
 
 -- close the persistent connection
 SELECT dblink_disconnect();
 
--- should generate "no connection available" error
+-- should generate "no connection to the server" error
 SELECT *
 FROM dblink('SELECT * FROM foo') AS t(a int, b text, c text[])
 WHERE t.a > 7;
@@ -143,3 +143,98 @@ WHERE a = 11;
 
 -- close the persistent connection
 SELECT dblink_disconnect();
+
+--
+-- tests for the new named persistent connection syntax
+--
+
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+
+-- use the named persistent connection
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- create a second named persistent connection
+-- should error with "cannot save named connection"
+SELECT dblink_connect('myconn','dbname=regression');
+
+-- create a second named persistent connection with a new name
+SELECT dblink_connect('myconn2','dbname=regression');
+
+-- use the second named persistent connection
+SELECT *
+FROM dblink('myconn2','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- close the second named persistent connection
+SELECT dblink_disconnect('myconn2');
+
+-- open a cursor
+SELECT dblink_open('myconn','rmt_foo_cursor','SELECT * FROM foo');
+
+-- fetch some data
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+-- this one only finds three rows left
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+-- close the cursor
+SELECT dblink_close('myconn','rmt_foo_cursor');
+
+-- should generate "cursor not found: rmt_foo_cursor" error
+SELECT *
+FROM dblink_fetch('myconn','rmt_foo_cursor',4) AS t(a int, b text, c text[]);
+
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+
+-- should generate "missing "=" after "myconn" in connection info string" error
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE t.a > 7;
+
+-- create a named persistent connection
+SELECT dblink_connect('myconn','dbname=regression');
+
+-- put more data into our slave table, using named persistent connection syntax
+-- but truncate the actual return value so we can use diff to check for success
+SELECT substr(dblink_exec('myconn','INSERT INTO foo VALUES(11,''l'',''{"a11","b11","c11"}'')'),1,6);
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[]);
+
+-- change some data
+SELECT dblink_exec('myconn','UPDATE foo SET f3[2] = ''b99'' WHERE f1 = 11');
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+
+-- delete some data
+SELECT dblink_exec('myconn','DELETE FROM foo WHERE f1 = 11');
+
+-- let's see it
+SELECT *
+FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
+WHERE a = 11;
+
+-- close the named persistent connection
+SELECT dblink_disconnect('myconn');
+
+-- close the named persistent connection again
+-- should get "connection named "myconn" not found" error
+SELECT dblink_disconnect('myconn');