Glossary
T
table
A named data object consisting of a
specific number of columns and some unordered rows. See also base table.
table designator
A column name qualifier that designates a
specific object table.
table queue
A mechanism for transferring rows between
database nodes. Table queues are distributed row streams with simplified rules
for the insertion and removal of rows. Table queues can also be used to
deliver rows between different processes in the serial database.
table space
An abstraction of a collection of
containers into which database objects are stored. A table space provides a
level of indirection between a database and the tables stored within the
database. A table space:
- Has space on media storage devices assigned to it.
- Has tables created within it. These tables will consume space in the
containers that belong to the table space. The data, index, long field, and
LOB portions of a table can be stored in the same table space, or can be
individually broken out into separate table spaces.
See also system managed space (SMS) table space, database managed space
(DMS) table space, long table space, regular table space, temporary table
space.
table space container
A generic term describing an allocation of
space to a table space. Depending on the table space type, the container can
be a directory, device, or file.
target server
The database location of the target table.
Normally this is also the location of the Apply program.
target table
The table on the target server to which
data is copied. It can be a user copy table, a point-in-time table, a base
aggregate table, a change aggregate table, a consistent change data table, or
a replica table.
TCP/IP
Transmission Control Protocol/Internet
Protocol.
temporary table
A table created during the processing of
an SQL statement to hold intermediate results.
temporary table space
A table space that can store only
temporary tables.
territory
A portion of the POSIX** locale that is
mapped to the country code for internal processing by the database manager.
thread
In some operating systems, the smallest
unit of operation to be performed in a process.
threshold trigger
An event occurring when the value of a
performance variable exceeds or falls below a user-defined threshold value.
The action that occurs as a result of a threshold trigger could be:
- Logging information in an alert log file
- Displaying information in an alert log window
- Generating an audio alarm
- Issuing a message window
- Invoking a predefined command or program
time
A three-part value that designates a time
of day in hours, minutes, and seconds.
time duration
A DECIMAL(6,0) value that represents a
number of hours, minutes, and seconds.
timeron
A unit of measurement used to give a rough
relative estimate of the resources, or cost, required by the database server
to execute two plans for the same query. The resources calculated in the
estimate include weighted CPU and I/O costs.
timestamp
A seven-part value that consists of a date
and time expressed in years, months, days, hours, minutes, seconds, and
microseconds.
timestamp duration
A DECIMAL(20,6) value that represents a
number of years, months, days, hours, minutes, seconds, and microseconds.
TM Database
Transaction Manager Database.
TP
Transaction program.
token
The basic syntactic unit of a computing
language. A token consists of one or more characters, excluding the blank
character, and excluding characters within a string constant or delimited
identifier.
topology and routing services (TRS)
An APPN control point component that
manages the topology database and computes routes.
trace table
A table that contains a high-level record
of the execution of the Capture program.
transaction
An exchange between a workstation and a
program, two workstations, or two programs that accomplish a particular action
or result. An example is the entry of a customer's deposit and the update
of the customer's balance. Synonym for unit of work.
transaction compensation
A process that restores rows that are
affected by a committed transaction that is rejected. When a committed
transaction is rejected, the rows are restored to the state that they were in
before the transaction was committed.
transaction manager
Assigns identifiers to transactions,
monitors their progress, and takes responsibility for transaction completion
and failure recovery.
Transaction Manager Database (TM Database)
A database that is used to log
transactions when a two-phase commit (SYNCPOINT TWOPHASE) is used with DB2
databases. In the event of transaction failure, the TM Database information
can be accessed to resynchronize databases involved in the failed transaction.
transaction program (TP)
An application program that uses APPC to
communicate with a partner application program.
transition table
A named temporary table that contains the
transition values for each row affected by the triggering modification. An old
transition table contains the values of affected rows before the modification
is applied, and a new transition table contains the values of the affected
rows after the modification is applied.
transition variable
A variable that is valid only in FOR EACH
ROW triggers. It allows access to the transition values for the current row.
An old transition variable is the value of the row before the modification is
applied, and the new transition variable is the value of the row after the
modification is applied.
Transmission Control Protocol/Internet Protocol (TCP/IP)
A set of communications protocols that
provide peer-to-peer connectivity functions for both local and wide area
networks.
trigger
In DB2, an object in a database that is
invoked indirectly by the database manager when a particular SQL statement is
run.
triggered action
The action that is executed when the
trigger event occurs.
triggered-action condition
The search condition that controls the
execution of the SQL statements within the triggered action.
trigger event
In a trigger definition, an update
operation (INSERT, UPDATE, or DELETE statement) that causes the trigger to be
run.
truncation
The process of discarding part of a result
from an operation when it exceeds memory or storage capacity.
tuning parameters table
A table at the source server that contains
timing information used by the Capture program. The information
includes:
- How long to keep rows in the change data table.
- How much time can elapse before changes are stored in a database log or
journal.
- How often to commit changed data to the unit of work tables.
two-phase commit
A two-step process by which recoverable
resources and an external subsystem are committed. During the first step, the
database manager subsystems are polled to ensure that they are ready to
commit. If all subsystems respond positively, the database manager instructs
them to commit.
typed parameter marker
A parameter marker that is specified along
with its target data type. It has the general form:
CAST(? AS data-type)
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