NDB Cluster Internals  /  NDB Internals Glossary

Appendix A NDB Internals Glossary

This appendix contains terms and abbreviations that are found in or useful to understanding theNDB source code.

ACC. ACCelerator orACCess manager. Implemented as theDBACC kernel block, which handles hash indexes of primary keys, providing fast access to records.

API node.  InNDB terms, this is any application that accesses cluster data using theNDB API, includingmysqld when functioning as an API node. (MySQL servers acting in this capacity are also referred to as“SQL nodes”.) Sometimes abbreviated informally as“API”. SeeNDB Cluster Nodes, Node Groups, Fragment Replicas, and Partitions.

BACKUP.  In theNDB kernel, the block having this name performs online backups and checkpoints. For more information, seeSection 4.1, “The BACKUP Block”.

CMVMI.  Stands forClusterManagerVirtualMachineInterface. AnNDB kernel handling nonsignal requests to the operating system, as well as configuration management, interaction with the cluster management server, and interaction between various kernel blocks and theNDB virtual machine. SeeSection 4.2, “The CMVMI Block”, for more information.

CNTR.  Stands for restartCoordiNaToR. SeeSection 4.14, “The NDBCNTR Block”, for more information.

DBINFO.  TheDatabaseInformation block provides support for thendbinfo information database used to obtain information about data node internals. SeeSection 4.6, “The DBINFO Block”.

DBTC.  The transaction coordinator (also sometimes written simply asTC). SeeSection 4.9, “The DBTC Block”, for more information.

DICT.  TheNDB dataDICTionary kernel block. AlsoDBDICT. SeeSection 4.4, “The DBDICT Block”.

DIH. DIstributionHandler. AnNDB kernel block. SeeSection 4.5, “The DBDIH Block”.

LDM. LocalDataManager. This set of NDB kernel blocks executes the code that manages the data handled on a given data node. It includes theDBTUP,DBACC,DBLQH,DBTUX,BACKUP,TSMAN,LGMAN,PGMAN, andRESTORE blocks.

Each such set of modules is referred to as an LDM instance, and is responsible for tuple storage, hash and T-tree indexes, page buffer and tablespace management, writing and restoring local checkpoints, and Disk Data log management. A data node can have multiple LDM instances, each of which can be distributed among a set of threads. Each LDM instance works with its own partition of the data.

LGMAN.  TheLogGroupMANagerNDB kernel block, used for NDB Cluster Disk Data tables. SeeSection 4.13, “The LGMAN Block”.

LQH. LocalQueryHandler.NDB kernel block, discussed inSection 4.7, “The DBLQH Block”.

MGM. ManaGeMent node (or management server). Implemented as thendb_mgmd server daemon. Responsible for passing cluster configuration information to data nodes and performing functions such as starting and stopping nodes. Accessed by the user by means of the cluster management client (ndb_mgm). A discussion of management nodes can be found inndb_mgmd — The NDB Cluster Management Server Daemon.

NDB_STTOR. NDBSTarTOrRestart

QMGR.  The cluster management block in theNDB kernel. It responsibilities include monitoring heartbeats from data and API nodes. SeeSection 4.17, “The QMGR Block”, for more information.

RBR. Row-BasedReplication. NDB Cluster Replication is row-based replication. SeeNDB Cluster Replication.

STTOR. STarTOrRestart

SUMA.  The clusterSUbscriptionMAnager. SeeSection 4.19, “The SUMA Block”.

TC. TransactionCoordinator. SeeSection 4.9, “The DBTC Block”.

TRIX.  Stands forTRansactions andIndeXes, which are managed by theNDB kernel block having this name. SeeSection 4.23, “The TRIX Block”.

TSMAN. Tablespacemanager. Handles tablespaces for NDB Cluster Disk Data. SeeSection 4.22, “The TSMAN Block”, for more information.

TUP. TUPle. Unit of data storage. Also used (along withDBTUP) to refer to theNDB kernel's tuple management block, which is discussed inSection 4.10, “The DBTUP Block”.