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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: 

•Data size, in particular the quantity of data stored in TEXT  columns or BLOB  columns (or both types of columns) 

•Having a data node (ndbd or ndbmtd) on the same host as an SQL node that is engaged in binary logging 

•Large number of rows per transaction or transaction batch 

•Configuration issues such as insufficient SendBufferMemory 

•Hardware issues such as insufficient RAM or poor network connectivity 

See also Section 23.3.3.14, “Configuring NDB Cluster Send Buffer Parameters” . 

## 23.5.15 INFORMATION_SCHEMA Tables for NDB Cluster 

Two INFORMATION_SCHEMA  tables provide information that is of particular use when managing an NDB Cluster. The FILES  table provides information about NDB Cluster Disk Data files (see Section 23.5.10.1, “NDB Cluster Disk Data Objects” ). The ndb_transid_mysql_connection_map  table provides a mapping between transactions, transaction coordinators, and API nodes. 

Additional statistical and other data about NDB Cluster transactions, operations, threads, blocks, and other aspects of performance can be obtained from the tables in the ndbinfo  database. For information about these tables, see Section 23.5.14, “ndbinfo: The NDB Cluster Information Database” . 

## 23.5.16 Quick Reference: NDB Cluster SQL Statements 

This section discusses several SQL statements that can prove useful in managing and monitoring a MySQL server that is connected to an NDB Cluster, and in some cases provide information about the cluster itself. 

• SHOW ENGINE NDB STATUS , SHOW ENGINE NDBCLUSTER STATUS 

The output of this statement contains information about the server’s connection to the cluster, creation and usage of NDB Cluster objects, and binary logging for NDB Cluster replication. 

See Section 13.7.7.15, “SHOW ENGINE Statement” , for a usage example and more detailed information. 

• SHOW ENGINES 

This statement can be used to determine whether or not clustering support is enabled in the MySQL server, and if so, whether it is active. 

See Section 13.7.7.16, “SHOW ENGINES Statement” , for more detailed information. 

<img src='content_image/765563.jpg'>

## Note 

This statement does not support a LIKE  clause. However, you can use LIKE  to filter queries against the INFORMATION_SCHEMA.ENGINES  table, as discussed in the next item. 

• SELECT * FROM INFORMATION_SCHEMA.ENGINES [WHERE ENGINE LIKE ’NDB%’] 

