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AMP


DEFINITION

AMP, acronym for "Access Module Processor," is the type of vproc (Virtual Processor) used to manage the database, handle file tasks and and manipulate the disk subsystem in the multi-tasking and possibly parallel-processing environment of the Teradata Database.


OVERVIEW

In reality, each AMP is an instance of the database management software responsible for accessing and manipulating data. As such, every AMP is allowed a part of the database to manage, and a part of the physical disk space to keep its set of database tables. Usually, the AMP obtains its portion of the disk space by being associated with a virtual disk (vdisk). It handles its disk reading / writing by using its file system software, which converts AMP steps (i.e., the steps from PEs) into physical data block requests. The AMPs are responsible to access and manipulate the data so as to complete the request processing. There may be mutiple AMPs on one node, and the communication among the AMPs is controlled by the BYNET.

The AMP vproc was invented with Teradata V2 to replace its dedicated physical predecessor on the DBC 1012 systems. In Teradata V1, the Access Module Processor (AMP) was the physical processing unit for all the Teradata database functions. Each AMP then contained its own microprocessor, disk drive, file system, database software (Database Manager), Teradata Operating System (TOS), and YNET interface. In that sense, each AMP was a node.

In Teradata V2, AMPs become software entities, and thus more flexible units that "deliver basic query parallelism to all work in the system." The number of AMPs (2 - 20 per node) is defined for the Teradata database before the database is loaded. The system partitions database tables across all the defined AMPs via hash functions to enable subquery-level parallel processing. In practice, all the database operations are run in parallel across all the AMPs, where all the related data rows are being processed simultaneously but independently.


FUNCTIONS

The functions of AMP can be classified as the following:

   1. BYNET interface, or Boardless BYNET interface;
   2. Database management:
         1. Locking;
         2. Joining;
         3. Sorting;
         4. Aggregation;
         5. Output data conversion;
         6. Disk space management;
         7. Accounting;
         8. Journaling;
   3. File-subsystem management;
   4. Disk-subsystem management.


SIZE LIMITS

 AMP SIZE LIMITS FOR TERADATA DATABASE

TERADATA DATABASE RELEASE     MAX CYLINDERS     MAX (BASE 2)     MAX (BASE 10)
V2R6.2.0.0 - UP                                 700,000                 1.26 TB     1.39 TB
V2R5.0.0.0 - V2R6.1.x.x                     600,000                 1.08 TB     1.19 TB
V2R4.0.1.0 - V2R4.1.3.x                     700,000                 1.26 TB     1.39 TB
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