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The following are DBMS Server facilities, which are configured using DBMS Server configuration parameters:
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Abstract Data Type Facility (ADF) does all the work that involves data types. It manipulates floating-point numbers, character strings, integers, and all the conversions and comparisons between them. This facility can be executed independently from the server so that other Ingres tools can also use ADF.
This abstract data type facility is also compiled into the Ingres tools such as QBF (Query-By-Forms) and the Terminal Monitor. It is used to manipulate Ingres data types in the front-end process before sending them to the DBMS Server.
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Compatibility Library Facility (CLF) provides the Ingres DBMS Server with a platform independent interface to the operating system. It contains functions that perform services such as disk I/O, memory management, Semaphore manipulation, and context switching (when Ingres threading is configured). It also provides low level system communications functions.
For example, when a thread in the DBMS is idle, it normally shows up in iimonitor, IPM, or VDBA as having current facility CLF. This indicates that the thread is executing a CLF function to read information from the communications channel that connects the thread to the system process that instigated the database connection associated with this thread.
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The Data Manipulation Facility (DMF) manages the DBMS Server interface to disk storage. In addition to managing all storage structures (hash, heap, ISAM, B-tree, BLOBs, and so on), DMF uses the logging and locking systems to control transaction processing and to handle concurrency issues. Included within DMF is a buffer manager that controls access to a cache (possibly shared) of database pages.
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The Optimizer Facility (OPF) selects the optimal plan for implementing queries. It also converts the query tree that comes out of the parser into the query execution plan (QEP). OPF uses a memory pool for its operations.
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The Parser Facility (PSF) converts queries from text form to internal format. The parser adds data from the system catalogs to the query, such as information about the table structure and keys that the optimizer needs to make a useful query plan.
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The Query Execution Facility (QEF) executes query plans and database utilities. It provides internal query services that other facilities use. QEF manages repeat queries, transactions, and cursors.
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The Query Storage Facility (QSF) provides shared memory facilities with a temporary or permanent place to store query trees and query plans.
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The System Control Facility (SCF) is the central controlling facility that manages sessions on behalf of user (client) requests. It coordinates the actions among the various facilities involved in processing a query, including thread monitoring and switching. SCF is also responsible for managing server-wide access to shared resources, such as operating system semaphores and memory.
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The Relation Description Facility (RDF) is a central caching point for information about tables. RDF is used by Ingres Star, PSF, and OPF.