postgresql plugin: Added support for protocol versions less than 3.

[collectd.git] / src / postgresql.c

diff --git a/src/postgresql.c b/src/postgresql.c
index eb7587f..fbc117b 100644 (file)
--- a/src/postgresql.c
+++ b/src/postgresql.c
@@ -103,6 +103,8 @@ typedef struct {
        PGconn      *conn;
        c_complain_t conn_complaint;
 
+       int proto_version;
+
        int max_params_num;
 
        /* user configuration */
@@ -209,6 +211,8 @@ static c_psql_database_t *c_psql_database_new (const char *name)
        db->conn_complaint.last     = 0;
        db->conn_complaint.interval = 0;
 
+       db->proto_version = 0;
+
        db->max_params_num = 0;
 
        db->queries     = NULL;
@@ -323,6 +327,11 @@ static int c_psql_check_connection (c_psql_database_t *db)
                                        db->database, PQerrorMessage (db->conn));
                        return -1;
                }
+
+               db->proto_version = PQprotocolVersion (db->conn);
+               if (3 > db->proto_version)
+                       log_warn ("Protocol version %d does not support parameters.",
+                                       db->proto_version);
        }
 
        c_release (LOG_INFO, &db->conn_complaint,
@@ -330,20 +339,11 @@ static int c_psql_check_connection (c_psql_database_t *db)
        return 0;
 } /* c_psql_check_connection */
 
-static int c_psql_exec_query (c_psql_database_t *db, int idx)
+static PGresult *c_psql_exec_query_params (c_psql_database_t *db,
+               c_psql_query_t *query)
 {
-       c_psql_query_t *query;
-       PGresult       *res;
-
        char *params[db->max_params_num];
-
-       int rows, cols;
-       int i;
-
-       if (idx >= db->queries_num)
-               return -1;
-
-       query = db->queries[idx];
+       int   i;
 
        assert (db->max_params_num >= query->params_num);
 
@@ -364,9 +364,40 @@ static int c_psql_exec_query (c_psql_database_t *db, int idx)
                }
        }
 
-       res = PQexecParams (db->conn, query->query, query->params_num, NULL,
+       return PQexecParams (db->conn, query->query, query->params_num, NULL,
                        (const char *const *)((0 == query->params_num) ? NULL : params),
                        NULL, NULL, /* return text data */ 0);
+} /* c_psql_exec_query_params */
+
+static PGresult *c_psql_exec_query_noparams (c_psql_database_t *db,
+               c_psql_query_t *query)
+{
+       return PQexec (db->conn, query->query);
+} /* c_psql_exec_query_noparams */
+
+static int c_psql_exec_query (c_psql_database_t *db, int idx)
+{
+       c_psql_query_t *query;
+       PGresult       *res;
+
+       int rows, cols;
+       int i;
+
+       if (idx >= db->queries_num)
+               return -1;
+
+       query = db->queries[idx];
+
+       if (3 <= db->proto_version)
+               res = c_psql_exec_query_params (db, query);
+       else if (0 == query->params_num)
+               res = c_psql_exec_query_noparams (db, query);
+       else {
+               log_err ("Connection to database \"%s\" does not support parameters "
+                               "(protocol version %d) - cannot execute query \"%s\".",
+                               db->database, db->proto_version, query->name);
+               return -1;
+       }
 
        if (PGRES_TUPLES_OK != PQresultStatus (res)) {
                log_err ("Failed to execute SQL query: %s",
@@ -522,6 +553,8 @@ static int c_psql_init (void)
                if (0 != c_psql_check_connection (db))
                        continue;
 
+               db->proto_version = PQprotocolVersion (db->conn);
+
                server_host    = PQhost (db->conn);
                server_version = PQserverVersion (db->conn);
                log_info ("Sucessfully connected to database %s (user %s) "
@@ -530,7 +563,11 @@ static int c_psql_init (void)
                                PQdb (db->conn), PQuser (db->conn),
                                C_PSQL_SOCKET3 (server_host, PQport (db->conn)),
                                C_PSQL_SERVER_VERSION3 (server_version),
-                               PQprotocolVersion (db->conn), PQbackendPID (db->conn));
+                               db->proto_version, PQbackendPID (db->conn));
+
+               if (3 > db->proto_version)
+                       log_warn ("Protocol version %d does not support parameters.",
+                                       db->proto_version);
        }
 
        plugin_register_read ("postgresql", c_psql_read);