T

table

A named data object consisting of a specific number of columns and some unordered rows.

table check constraint

See [check constraint]

table collocation

In a partitioned database environment, a state that occurs when two tables are stored in the same database partition group and have the same number of compatible partitioning keys. When this happens, DB2 UDB can choose to perform the join or subquery processing at the database partition where the data is stored.

table expression

An expression that creates a temporary result table from a simple query. For example, a table expression might be a query that selects all the managers from several departments and further specifies that they have over 15 years of working experience and are located at the main branch.

table function

A function that optionally accepts arguments and returns a table to the SQL statement referencing it. Table functions can be referenced only in the FROM clause.

table lock

A lock on a table of data.

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. The data, index, long field, and LOB portions of a table can be stored in the same table space, or can be individually divided into separate table spaces.

table space container

An allocation of space to a table space. Depending on the table space type, the container can be a directory, device, or file.

table space high water mark

The table space high water mark is the first page after the highest page number that has been allocated within the table space.

task

In the Task Center, a unit of work and its associated schedule and task actions. Tasks can be set to run on schedules and can perform various actions based on the success or failure of the task. DB2 UDB scripts, operating scripts, and warehouse steps are all examples of tasks.

Task Center

The DB2 UDB graphical interface for organizing task flow, scheduling tasks, and distributing notifications about the status of completed tasks.

TCP/IP

See [Transmission Control Protocol/Internet Protocol]

TCP/IP port

A 2-byte value that identifies a TCP/IP network application within a TCP/IP host.

temporary table

A table that holds temporary data. For example, temporary tables are useful for holding or sorting intermediate results from queries that contain a large number of rows. The two kinds of temporary tables, which are created by different SQL statements, are the created temporary table and the declared temporary table.

temporary table space

A table space that can store only temporary tables.

territory code

A code used by DB2 UDB to preset the default collation order for an SBCS database and to establish monetary, date, time, and numeric formatting that is specific to a country, region, or territory.

throttled utilities

Utilities with a limit placed on the resources that would otherwise be consumed. The degree to which the resources are limited is based on the current workload of the system. Supported utilities include backup, restore, and table space reorganization.

timeron

A unit of measurement that gives 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 processor and I/O costs.

timestamp

A data type that contains a seven-part value that consists of a date and time expressed in years, months, days, hours, minutes, seconds, and microseconds.

Tivoli Storage Manager (TSM)

A client-server product that provides storage management and data access services in a heterogeneous environment. TSM supports various communication methods, provides administrative facilities to manage the backup and storage of files, and provides facilities for scheduling backups.

transaction

An atomic series of SQL statements that make up a logical unit of work. All of the data modifications made during a transaction are either committed together as a unit or are all rolled back as a unit. Synonym for unit of work.

transaction manager

A function that assigns identifiers to transactions, monitors their progress, and takes responsibility for transaction completion and failure recovery.

transition table

A temporary table that contains all the affected rows of the subject table in their state before or after the triggering event occurs. Triggered SQL statements in the trigger definition can reference the table of changed rows in the old or new state.

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; the new transition variable is the value of the row after the modification is applied.

Transmission Control Protocol/Internet Protocol (TCP/IP)

An industry standard, nonproprietary set of communications protocols that provide reliable end-to-end connections between applications over interconnected networks of different types.

trigger

A database object associated with a single base table or view that defines a rule. The rule consists of a set of SQL statements that run when an insert, update, or delete database operation occurs on the associated base table or view.

truncation

The process of discarding part of a result from an operation when it exceeds memory or storage capacity.

trusted clients

DB2 clients with reliable security facilities like Windows 2000, AIX, z/OS, and Linux.

TSM

See [Tivoli Storage Manager]

tuple

A synonym for a row in a table.

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 table

A table in which the data type of each column is defined separately or the types for the columns are based on the attributes of a user-defined structured type.