keep-dead-connection-for-reconnects-1.patch

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 39a460d85c..a6b1d7533d 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -3060,26 +3060,29 @@ do_connect(enum trivalue reuse_previous_specification,
 			break;
 	}
 
-	/*
-	 * If we are to re-use parameters, there'd better be an old connection to
-	 * get them from.
-	 */
-	if (reuse_previous && !o_conn)
-	{
-		pg_log_error("No database connection exists to re-use parameters from");
-		return false;
-	}
-
 	/*
 	 * If we intend to re-use connection parameters, collect them out of the
-	 * old connection, then replace individual values as necessary. Otherwise,
+	 * old connection, then replace individual values as necessary.  (We may
+	 * need to resort to looking at pset.dead_conn, if the connection died
+	 * previously or a previous non-interactive \connect failed.)  Otherwise,
 	 * obtain a PQconninfoOption array containing libpq's defaults, and modify
 	 * that.  Note this function assumes that PQconninfo, PQconndefaults, and
 	 * PQconninfoParse will all produce arrays containing the same options in
 	 * the same order.
 	 */
 	if (reuse_previous)
-		cinfo = PQconninfo(o_conn);
+	{
+		if (o_conn)
+			cinfo = PQconninfo(o_conn);
+		else if (pset.dead_conn)
+			cinfo = PQconninfo(pset.dead_conn);
+		else
+		{
+			/* This should be unreachable, but just in case ... */
+			pg_log_error("No database connection exists to re-use parameters from");
+			return false;
+		}
+	}
 	else
 		cinfo = PQconndefaults();
 
@@ -3360,10 +3363,14 @@ do_connect(enum trivalue reuse_previous_specification,
 			if (o_conn)
 			{
 				/*
-				 * Transition to having no connection.  Keep this bit in sync
-				 * with CheckConnection().
+				 * Transition to having no live connection; but stash away the
+				 * previous connection so that we can still refer to its
+				 * parameters in a later \connect attempt.  Keep this bit in
+				 * sync with CheckConnection().
 				 */
-				PQfinish(o_conn);
+				if (pset.dead_conn)
+					PQfinish(pset.dead_conn);
+				pset.dead_conn = o_conn;
 				pset.db = NULL;
 				ResetCancelConn();
 				UnsyncVariables();
@@ -3421,8 +3428,15 @@ do_connect(enum trivalue reuse_previous_specification,
 				   PQdb(pset.db), PQuser(pset.db));
 	}
 
+	/* Drop no-longer-needed connection(s) */
 	if (o_conn)
 		PQfinish(o_conn);
+	if (pset.dead_conn)
+	{
+		PQfinish(pset.dead_conn);
+		pset.dead_conn = NULL;
+	}
+
 	return true;
 }
 
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index 6323a35c91..80fcd6a0d6 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -313,10 +313,14 @@ CheckConnection(void)
 			fprintf(stderr, _("Failed.\n"));
 
 			/*
-			 * Transition to having no connection.  Keep this bit in sync with
+			 * Transition to having no connection; but stash away the failed
+			 * connection so that we can still refer to its parameters in a
+			 * later \connect attempt.  Keep this bit in sync with
 			 * do_connect().
 			 */
-			PQfinish(pset.db);
+			if (pset.dead_conn)
+				PQfinish(pset.dead_conn);
+			pset.dead_conn = pset.db;
 			pset.db = NULL;
 			ResetCancelConn();
 			UnsyncVariables();
diff --git a/src/bin/psql/settings.h b/src/bin/psql/settings.h
index 97941aa10c..9601f6e90c 100644
--- a/src/bin/psql/settings.h
+++ b/src/bin/psql/settings.h
@@ -117,6 +117,13 @@ typedef struct _psqlSettings
 
 	VariableSpace vars;			/* "shell variable" repository */
 
+	/*
+	 * If we get a connection failure, the now-unusable PGconn is stashed here
+	 * until we can successfully reconnect.  Never attempt to do anything with
+	 * this PGconn except extract parameters for a \connect attempt.
+	 */
+	PGconn	   *dead_conn;		/* previous connection to backend */
+
 	/*
 	 * The remaining fields are set by assign hooks associated with entries in
 	 * "vars".  They should not be set directly except by those hook
diff --git a/src/bin/psql/startup.c b/src/bin/psql/startup.c
index 8232a0143b..e8d35a108f 100644
--- a/src/bin/psql/startup.c
+++ b/src/bin/psql/startup.c
@@ -145,6 +145,7 @@ main(int argc, char *argv[])
 	pset.progname = get_progname(argv[0]);
 
 	pset.db = NULL;
+	pset.dead_conn = NULL;
 	setDecimalLocale();
 	pset.encoding = PQenv2encoding();
 	pset.queryFout = stdout;
@@ -442,7 +443,10 @@ error:
 	/* clean up */
 	if (pset.logfile)
 		fclose(pset.logfile);
-	PQfinish(pset.db);
+	if (pset.db)
+		PQfinish(pset.db);
+	if (pset.dead_conn)
+		PQfinish(pset.dead_conn);
 	setQFout(NULL);
 
 	return successResult;