Databases Reference
In-Depth Information
Outer join
A query returning qualifying rows from one table and all rows from the
second “outer” table.
Output parameter
A value returned by a procedure.
Packet size
Network communication parameter setting the maximum amount of data
that can be sent at one time.
Paging file
An area of hard disk storage set aside for use as system memory.
Parameters
Values provided that help determine how a command runs.
Partial functional dependency
A dependency where data is dependent on part of the
primary key.
Partial rollback
A process by which part, but not all, of the statements in a transaction
are reversed.
Partial update
A condition when only part of the tables involved in an operation are
updated instead of updating all tables.
Performance baseline
Performance data you collect to use for comparison later when
performance problems are suspected.
Performance counter
Module designed to monitor a specific aspect of system or appli-
cation performance.
Performance object
A group of related performance counters.
Phantom read
A condition where a row appears or disappears in subsequent reads of
the same data.
Phantom
A data row that has appeared or disappeared in a subsequent read of the
same data.
Physical data pointer
Value used to link and associate data in the hierarchical and
network database models. Values to link data values to physical storage locations in
many implementations of the relational database model.
Physical design
Design process that includes identifying and implementing the physical
database and database objects.
Physical security
Protecting data against physical corruption or loss; typically involves
protecting the server, ensuring the storage media and duplicating data.
Precedence constraint
Decision point within a maintenance plan used to control
execution.
Prepare phase
Initial phase of the two-phase commit process where the databases are
prepared for update.
Primary index
Index for a table's primary key.
Primary key
Database object used to enforce uniqueness in a table.
Procedure
Compiled set of executable statements.
Processor affinity
Configuration settings relating to multiple processor use.
Production database
Database that provides support for day-to-day business activities.
