Databases Reference
In-Depth Information
D
data provider
A software component that an application uses on demand to gain access to a database
using one of the following standards-defined APIs: ADO.NET, ADO, or OLE DB. Among
many other things, a data provider processes the API function calls, submits SQL
requests to the database, and returns results to the application.
Data Services Layer (DSL)
In a Service-Oriented Architecture (SOA) environment, data access logic and code
designed as a loosely coupled SOA service.
database driver
A software component that an application uses on demand to gain access to a database
using one of the following standards-defined APIs: ODBC or JDBC. Among many other
things, a database driver processes API function calls, submits SQL requests to the data-
base, and returns results to the application.
database protocol packets
A package that database drivers and database servers use to request and return informa-
tion. Each packet uses a protocol for communication with the database defined by the
database vendor. For example, Microsoft SQL Server uses communication encoded with
the Tabular Data Stream (TDS) protocol, and IBM DB2 uses communication encoded
with the Distributed Relational Database Architecture (DRDA) protocol.
disk contention
A situation that occurs when multiple processes or threads try to access the same disk
simultaneously. The disk has a limit on how many processes/threads can access it and the
amount of data that it can transfer. When these limits are reached, processes/threads
must wait to access the disk.
distributed transaction
A transaction that accesses and updates data on two or more networked databases and
therefore, must be coordinated among those databases.
See also
local transaction.
dynamic SQL
SQL statements that are constructed at runtime; for example, the application may allow
users to enter their own queries. These types of SQL statements are not hard-coded into
the application.
See also
static SQL.
