Movatterモバイル変換

This table contains aggregated information about NDB transporters. In NDB 8.0.37 and later, you can obtain similar information about individual transporters from thetransporter_details table.

Thetransporters table contains the following columns:

Notes

For each running data node in the cluster, thetransporters table displays a row showing the status of each of that node's connections with all nodes in the cluster,including itself. This information is shown in the table'sstatus column, which can have any one of the following values:CONNECTING,CONNECTED,DISCONNECTING, orDISCONNECTED.

Connections to API and management nodes which are configured but not currently connected to the cluster are shown with statusDISCONNECTED. Rows where thenode_id is that of a data node which is not currently connected are not shown in this table. (This is similar omission of disconnected nodes in thendbinfo.nodes table.

Theremote_address is the host name or address for the node whose ID is shown in theremote_node_id column. Thebytes_sent from this node andbytes_received by this node are the numbers, respectively, of bytes sent and received by the node using this connection since it was established. For nodes whose status isCONNECTING orDISCONNECTED, these columns always display0.

Assume you have a 5-node cluster consisting of 2 data nodes, 2 SQL nodes, and 1 management node, as shown in the output of theSHOW command in thendb_mgm client:

ndb_mgm> SHOWConnected to Management Server at: localhost:1186Cluster Configuration---------------------[ndbd(NDB)]     2 node(s)id=1    @10.100.10.1  (8.0.44-ndb-8.0.44, Nodegroup: 0, *)id=2    @10.100.10.2  (8.0.44-ndb-8.0.44, Nodegroup: 0)[ndb_mgmd(MGM)] 1 node(s)id=10   @10.100.10.10  (8.0.44-ndb-8.0.44)[mysqld(API)]   2 node(s)id=20   @10.100.10.20  (8.0.44-ndb-8.0.44)id=21   @10.100.10.21  (8.0.44-ndb-8.0.44)

There are 10 rows in thetransporters table—5 for the first data node, and 5 for the second—assuming that all data nodes are running, as shown here:

mysql> SELECT node_id, remote_node_id, status    ->   FROM ndbinfo.transporters;+---------+----------------+---------------+| node_id | remote_node_id | status        |+---------+----------------+---------------+|       1 |              1 | DISCONNECTED  ||       1 |              2 | CONNECTED     ||       1 |             10 | CONNECTED     ||       1 |             20 | CONNECTED     ||       1 |             21 | CONNECTED     ||       2 |              1 | CONNECTED     ||       2 |              2 | DISCONNECTED  ||       2 |             10 | CONNECTED     ||       2 |             20 | CONNECTED     ||       2 |             21 | CONNECTED     |+---------+----------------+---------------+10 rows in set (0.04 sec)

If you shut down one of the data nodes in this cluster using the command2 STOP in thendb_mgm client, then repeat the previous query (again using themysql client), this table now shows only 5 rows—1 row for each connection from the remaining management node to another node, including both itself and the data node that is currently offline—and displaysCONNECTING for the status of each remaining connection to the data node that is currently offline, as shown here:

mysql> SELECT node_id, remote_node_id, status    ->   FROM ndbinfo.transporters;+---------+----------------+---------------+| node_id | remote_node_id | status        |+---------+----------------+---------------+|       1 |              1 | DISCONNECTED  ||       1 |              2 | CONNECTING    ||       1 |             10 | CONNECTED     ||       1 |             20 | CONNECTED     ||       1 |             21 | CONNECTED     |+---------+----------------+---------------+5 rows in set (0.02 sec)

Theconnect_count,overloaded,overload_count,slowdown, andslowdown_count counters are reset on connection, and retain their values after the remote node disconnects. Thebytes_sent andbytes_received counters are also reset on connection, and so retain their values following disconnection (until the next connection resets them).

Theoverload state referred to by theoverloaded andoverload_count columns occurs when this transporter's send buffer contains more thanOVerloadLimit bytes (default is 80% ofSendBufferMemory, that is, 0.8 * 2097152 = 1677721 bytes). When a given transporter is in a state of overload, any new transaction that tries to use this transporter fails with Error 1218 (Send Buffers overloaded in NDB kernel). This affects both scans and primary key operations.

Theslowdown state referenced by theslowdown andslowdown_count columns of this table occurs when the transporter's send buffer contains more than 60% of the overload limit (equal to 0.6 * 2097152 = 1258291 bytes by default). In this state, any new scan using this transporter has its batch size reduced to minimize the load on the transporter.

Common causes of send buffer slowdown or overloading include the following:

See alsoSection 25.4.3.14, “Configuring NDB Cluster Send Buffer Parameters”.