bdfm1m0zMessages (System Error, Online, Offline) and Master Glossary

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data block
A term used with B+Tree indexing that refers to any block in a B+Tree file that is not being used as a node block.

data collection
In the TPFDF product, a facility that collects system activity data used to analyze TPFDF performance.

data identifier (DID)
A 2-byte field that identifies the userLREC part of an extended logical record (LREC).

data level independence (DLI)
In the TPFDF product, a term used to indicate that all data levels holding blocks before a macro or function are preserved across the call.

database administrator
The person who is typically responsible for designing TPFDF files. The responsibilities of the administrator can include coding DSECT macros and database definitions (DBDEFs).

database definition (DBDEF) macro
A macro that generates database definition (DBDEF) tables each of which defines the major characteristics of a TPFDF file. If the file is an index or detail file, the DBDEF macro defines relations between this file and others in the index structure. There is one DBDEF macro statement for each file in the system.

database definition (DBDEF) table
A table that is located in main storage for each TPFDF file ID. Each table contains information that defines the characteristics of the file. The information used to define a DBDEF table consists of:

This table ensures a centralized capability for maintaining TPFDF attributes by providing the TPFDF product with the file characteristics and accessing information required to process a file.

database definition (DBDEF) index table
A table containing one entry for each TPFDF file ID. Each item contains the address of a DBDEF table that defines the characteristics of that file.

database interface block (DBIFB)
A TPFDF work block containing information about each open subfile. The information about each subfile is contained in a SW00SR slot.

DBDEF macro
Database definition macro.

DBDEF table
Database definition table.

DBDEF index table
Database definition index table.

DBIFB
Database interface block.

DDA
Distributed Data Access.

default key
A key defined in a DBDEF macro statement that is used to determine the placement of logical records (LRECs) in a file as they are added to a file, and to select LRECs as they are read from a file.

default-key key list
A key list that is used to determine which key set in a file's database definition (DBDEF) should be used to select logical records from the database.

detac mode
When a program opens a subfile in detac mode, the TPFDF product retains all blocks that it reads or writes in main storage. The TPFDF product only writes modified blocks to DASD when the application program checkpoints the subfile or closes the subfile without using the ABORT parameter. See also checkpoint.

detail file
The lowest-level file in an indexed structure. The simplest type of indexing consists of a single top-level index file referencing a detail file. Relationships between index files and detail files are defined by the database administrator (by coding instructions in the DBDEF macro). See also index file, intermediate index file, top-level index file.

DID
Data identifier.

Distributed Data Access (DDA)
See TPFDF Distributed Data Access (TPFDF/DDA).

DLI
Data level independence.

DSECT
Data definition (assembler) macro. In the TPFDF product, each DSECT macro defines the characteristics of a single file. The database administrator codes a DSECT macro to define the layout of LRECs, block sizes, file processing options, algorithm to be used, and other details of a file.