SQL/MP Glossary

Glossary
Compaq NonStop™ SQL/MP Glossary—429832-001
Glossary-23
process file segment (PFS)
process file segment (PFS). A proprietary extended data segment, defined by the file system,
that contains the user’s process context and the working storage for the file system.
process identification number. See PIN (process identification number)
.
process name. An operating system name that can be assigned to a process when the process
is created. A process name uniquely identifies a process or process pair on a node.
program catalog version (PCV). A version that indicates the oldest version of a catalog in
which the SQL program can be registered. The NonStop SQL/MP features used in the
program determine the program catalog version.
program format version (PFV). A version that indicates the oldest version of the
NonStop SQL/MP executor that can execute an SQL program. The version number is
determined by the version of the SQL compiler that compiled the program.
program independence. The ability to change an application without changing the database.
Contrast with data independence
.
program invalidation. The process used by NonStop SQL/MP to mark an SQL program file
as SQL invalid. During program invalidation, NonStop SQL sets the VALID flag in the
PROGRAMS catalog table and in the program’s file label to N (if the program file is
accessible) and deletes the program’s usages entries in the USAGES table.
programmatic SQL. The SQL statements and directives that can be embedded in a host-
language program; the application programming interface for NonStop SQL/MP.
Contrast with SQLCI (SQL conversational interface)
.
projection. A database operation that selects one or more columns from a table. A projection
extracts a subset of the table’s columns and, optionally, eliminates duplicate rows within
the extracted columns. Contrast with restriction
.
protection view. A view defined with the protection attribute. The view can be derived from
a single table by taking a projection of the columns of the table, a restriction of the rows
in the table, or both. A protection view provides a form of column-level security because
the view can be secured, updated, and read. Contrast with shorthand view
.
qualified fileset list. A list of filesets optionally qualified by a clause that limits the selection
of objects or files. Contrast with simple fileset list
.
query. Generally, a request for data from the database; specifically, the execution of a
SELECT statement, which requests columns and rows from one or more tables and
views. In the context of the NonStop SQL/MP optimizer, a query is a request for data
access through any DML statement.
query execution plan. See execution plan
.
query optimization. The selection by the optimizer of the best available query execution
plan for each DML statement, including the access path, join order, type of join, sort
strategy, and so forth.