SQL/MX Glossary

Glossary
HP NonStop SQL/MX Glossary—523732-002
Glossary-39
trigger temporary table
trigger temporary table. A pseudo-temporary table created to implement triggers
efficiently. These tables are not temporary tables, as defined by ANSI, but an
implementation used to help execute triggers.
tuple. A data object containing two or more components.
type checking. Determines whether data types are compatible. See also compatible data
types.
type 1 plan. A parallel execution plan in which matching partitions exist in tables that are
involved in a join.
type 2 plan. A parallel execution plan the optimizer achieves by using parallel access to the
inner table. The optimizer may choose this type of plan when the inner and outer tables
do not match and repartitioning is undesirable or not possible.
U
UDR. See user-defined routine (UDR).
UID. See unique identifier (UID).
UMD. See user metadata (UMD).
unilateral abort. An abort caused by a participant in a transaction that is not yet in the
prepared state.
unique identifier (UID). An identifier, used in system metadata tables, that is generated
and assigned to each catalog, schema, object, and partition at the time it is created.
Each UID is unique only within a node.
unique index. An index in which the combined values of the columns that make up the
index uniquely identify the rows in the underlying base table.
upsert. An SQL insert operation that becomes an update operation if the target row already
exists.
user-defined routine (UDR). A routine registered with SQL/MX and invoked by SQL/MX
during execution of an SQL statement. A stored procedure is a type of UDR. See also
routine, stored procedure, and stored procedure in Java (SPJ).
user-defined transaction. A TMF transaction initiated by an application either in a program
unit or in a requester on whose behalf the program unit performs database operations.
Contrast with system-defined transaction.
user metadata (UMD). User schemas contain, in addition to user tables, a small number of
UMD tables. System schemas also contain UMD tables however, definition schemas
do not contain UMD tables. Contrast with system metadata (SMD).