Optionally don't error out due to preexisting slots in commandline utilities.

pg_receivexlog and pg_recvlogical error out when --create-slot is
specified and a slot with the same name already exists. In some cases,
especially with pg_receivexlog, that's rather annoying and requires
additional scripting.

Backpatch to 9.5 as slot control functions have newly been added to
pg_receivexlog, and there doesn't seem much point leaving it in a less
useful state.

Discussion: [email protected]

1 files changed, 19 insertions, 25 deletions

diff --git a/src/bin/pg_basebackup/streamutil.c b/src/bin/pg_basebackup/streamutil.c
index 0ed61440b09..a5cad350f8a 100644
--- a/src/bin/pg_basebackup/streamutil.c
+++ b/src/bin/pg_basebackup/streamutil.c
@@ -31,6 +31,8 @@
 #include "common/fe_memutils.h"
 #include "datatype/timestamp.h"
 
+#define ERRCODE_DUPLICATE_OBJECT  "42710"
+
 const char *progname;
 char	   *connection_string = NULL;
 char	   *dbhost = NULL;
@@ -314,7 +316,7 @@ RunIdentifySystem(PGconn *conn, char **sysid, TimeLineID *starttli,
  */
 bool
 CreateReplicationSlot(PGconn *conn, const char *slot_name, const char *plugin,
-					  XLogRecPtr *startpos, bool is_physical)
+					  bool is_physical, bool slot_exists_ok)
 {
 	PQExpBuffer query;
 	PGresult   *res;
@@ -336,12 +338,23 @@ CreateReplicationSlot(PGconn *conn, const char *slot_name, const char *plugin,
 	res = PQexec(conn, query->data);
 	if (PQresultStatus(res) != PGRES_TUPLES_OK)
 	{
-		fprintf(stderr, _("%s: could not send replication command \"%s\": %s"),
-				progname, query->data, PQerrorMessage(conn));
+		const char *sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
 
-		destroyPQExpBuffer(query);
-		PQclear(res);
-		return false;
+		if (slot_exists_ok && strcmp(sqlstate, ERRCODE_DUPLICATE_OBJECT) == 0)
+		{
+			destroyPQExpBuffer(query);
+			PQclear(res);
+			return true;
+		}
+		else
+		{
+			fprintf(stderr, _("%s: could not send replication command \"%s\": %s"),
+					progname, query->data, PQerrorMessage(conn));
+
+			destroyPQExpBuffer(query);
+			PQclear(res);
+			return false;
+		}
 	}
 
 	if (PQntuples(res) != 1 || PQnfields(res) != 4)
@@ -356,25 +369,6 @@ CreateReplicationSlot(PGconn *conn, const char *slot_name, const char *plugin,
 		return false;
 	}
 
-	/* Get LSN start position if necessary */
-	if (startpos != NULL)
-	{
-		uint32		hi,
-					lo;
-
-		if (sscanf(PQgetvalue(res, 0, 1), "%X/%X", &hi, &lo) != 2)
-		{
-			fprintf(stderr,
-				  _("%s: could not parse transaction log location \"%s\"\n"),
-					progname, PQgetvalue(res, 0, 1));
-
-			destroyPQExpBuffer(query);
-			PQclear(res);
-			return false;
-		}
-		*startpos = ((uint64) hi) << 32 | lo;
-	}
-
 	destroyPQExpBuffer(query);
 	PQclear(res);
 	return true;