Glossary
S
sargable
A predicate that can be evaluated as a
search argument. See predicate.
SBCS
Single-byte character set.
scalar fullselect
A fullselect that returns a single
value-- one row of data consisting of exactly one column.
scalar function
An SQL operation that produces a single
value from another value and is expressed as a function name followed by a
list of arguments enclosed in parentheses.
scale
The number of digits in the fractional
part of a number.
schema
A collection of database objects such as
tables, views, indexes, or triggers. It provides a logical classification of
database objects.
SDK
Software Developer's Kit.
search condition
A criterion for selecting rows from a
table. A search condition consists of one or more predicates.
secondary log
A set of one or more log files used to
record changes to a database. Storage for these files is allocated as needed
when the primary log is full.
self-referencing row
A row that is a parent of itself.
self-referencing subquery
A subselect or fullselect within a DELETE,
INSERT, or UPDATE statement that refers to the same table that is the object
of the SQL statement.
self-referencing table
A table that is both a parent and a
dependent table in the same referential constraint.
server
In a network, a node that provides
facilities to other stations; for example, a file server, a printer server, a
mail server.
service name
A name that provides a symbolic method of
specifying the port number to be used at a remote node. The TCP/IP connection
requires:
- The address of the remote node.
- The port number to be used on the remote node to identify an application.
session
A logical connection between two stations
or SNA network addressable units (NAUs) that allows the two stations or NAUs
to communicate.
session limit
In SNA, the maximum number of concurrently
active logical unit-logical unit (LU-LU) sessions that a particular logical
unit (LU) can support.
session partner
In SNA, one of the two network addressable
units (NAUs) participating in an active session.
session security
For LU 6.2, partner LU verification and
session data encryption. A Systems Network Architecture (SNA) function that
allows data to be transmitted in encrypted form.
set operator
The SQL operators UNION, EXCEPT, and
INTERSECT corresponding to the relational operators union, difference, and
intersection. A set operator derives a result table by combining two other
result tables.
shadowing
A recovery technique in which current page
contents are never overwritten. Instead, new pages are allocated and written
while the pages whose values are being replaced are retained as shadow copies
until they are no longer needed to support the restoration of the system state
due to a transaction rollback.
share lock
A lock that limits concurrently executing
application processes to read-only operations on database data.
short string
A fixed-length string or a varying-length
string whose maximum length is less than or equal to 254 bytes.
single-byte character set (SBCS)
A character set in which each character is
represented by a one-byte code. Contrast with double-byte character set,
multi-byte character set.
SMS table space
System managed space table space.
SNA
Systems Network Architecture.
SNA network
The part of the user application network
that conforms to the formats and protocols of Systems Network Architecture
(SNA). It enables reliable transfer of data among users and provides protocols
for controlling the resources of various network configurations. The SNA
network consists of network addressable units (NAUs), gateway function,
intermediate session routing function components, and the transport network.
snapshot
See performance snapshot, explain
snapshot.
Snapshot Monitor
An API used to assess the status of the
database manager, individual databases, tables, table spaces, and individual
applications.
soft checkpoint
The process of writing some information to
the log file header; this information is used to determine the starting point
in the log in case a database restart is required.
Software Developer's Kit (SDK)
An application development product that
allows applications to be developed on a client workstation to access remote
database servers including host relational databases through the DB2 Connect
products.
source function
A user-defined function (UDF) whose body
is used to implement one or more other UDFs.
source server
The database location of the replication
source and the Capture program.
source table
A table that contains the data that is to
be copied to a target table. The source table can be a replication source
table, a change data table, or a consistent change data table. Contrast with
target table.
source type
An existing type that is used to
internally represent a distinct type.
special register
A storage area that is defined for an
application process by the database manager and is used to store information
that can be referenced in SQL statements. Examples are USER and CURRENT DATE.
specific function name
The name that uniquely identifies a
function to the system.
SQL
A standardized language for defining and
manipulating data in a relational database.
SQLCA
SQL communication area.
SQL communication area (SQLCA)
A set of variables that provides an
application program with information about the execution of its SQL statements
or its requests from the database manager.
SQLDA
SQL descriptor area.
SQL descriptor area (SQLDA)
A set of variables that is used in the
processing of certain SQL statements. The SQLDA is intended for dynamic SQL
programs.
SSCP
System services control point.
stack
An area in memory that stores temporary
register information, parameters, and return addresses of subroutines.
staging table
A consistent change target table that is
used as the source for updating data to multiple target tables.
standard conflict detection
Conflict detection in which the Apply
program searches for conflicts in rows that are already captured in the
replica's change data tables. See also conflict detection, enhanced
conflict detection.
statement
An instruction in a program or procedure.
statement handle
In CLI, a handle that refers to the data
object that contains information about an SQL statement. This includes
information such as dynamic arguments, bindings for dynamic arguments and
columns, cursor information, result values, and status information. Each
statement handle is associated with a connection handle.
static SQL
SQL statements that are embedded within a
program, and are prepared during the program preparation process before the
program is executed. After being prepared, a static SQL statement does not
change, although values of host variables specified by the statement may
change.
stored procedure
A block of procedural constructs and
embedded SQL statements that is stored in a database and can be called by
name. Stored procedures allow an application program to be run in two parts.
One part runs on the client and the other on the server. This allows one call
to produce several accesses to the database. Synonymous with procedure.
string
In programming languages, the form of data
used for storing and manipulating text.
Structured Query Language
See SQL.
subagent
A type of agent that works on subrequests.
A single application can make many requests, and each request can be broken
into many subrequests. Therefore, there can be multiple subagents working on
behalf of the same application. All subagents working for the application are
coordinated by the coordinating agent for that application. See also
coordinating agent.
subordinate agent
See subagent.
subquery
A fullselect used within a search
condition of an SQL statement.
subscription cycle
The processing of a subscription set by
the Apply program.
subscription set
The specification of a group of source
tables, target tables, and the control information that governs the
replication of changed data. Updates are committed in the same transaction.
subselect
That form of a query that does not include
an ORDER BY clause, an UPDATE clause, or UNION operators.
symbolic destination name
Specifies the name of a remote partner.
The name corresponds to an entry in the CPI Communications side information
table that contains the necessary information (partner LU name, mode name,
partner TP name) for the client to set up an APPC connection to the server.
synchronization level
In APPC, the specification indicating
whether the corresponding transaction programs exchange confirmation requests
and replies.
synchronous
Pertaining to two or more processes that
depend upon the occurrences of specific events, such as a common timing
signal. Contrast with asynchronous.
sync point
Synonym for point of consistency.
system catalog
See catalog.
system database directory
A directory that contains entries for
every database that can be accessed using the database manager. It is created
when the first database is created or cataloged on the system.
system managed space (SMS) table space
A table space whose space is managed by
the operating system. This storage model is based on files created under
subdirectories, and managed by the file system. Contrast with database managed
space (DMS) table space.
system services control point (SSCP)
The control point in a SNA network that
provides network services for dependent nodes.
Systems Network Architecture (SNA)
The description of the logical structure,
formats, protocols, and operational sequences for transmitting information
units through the networks and also the operational sequences for controlling
the configuration and operation of networks.
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