Databases Reference
In-Depth Information
commit protocol to ensure transaction integrity and consistency across multiple sys‐
tems. This protocol is further described as we describe two-phase commit below.
Access to and from Non-Oracle Databases
Oracle's Gateways (illustrated in
Figure 13-1
) are Oracle software products that provide
users with access to non-Oracle databases via Oracle SQL. Oracle SQL is automatically
translated into the SQL of the target database, allowing applications developed for Ora‐
cle to be used against non-Oracle databases. You can also use native SQL syntax for the
target database, which can be sent directly to the target without translation. Oracle
datatypes such as NUMBER, CHAR, and DATE are converted into the datatypes of the
target. Oracle data dictionary views are provided for target data store objects. Hetero‐
geneous databases can also be accessed via Oracle database links to create a distributed
database.
Figure 13-1. Typical configuration and use of Oracle Gateways
Key heterogeneous database connectivity support and options include:
Heterogeneous Services
Heterogeneous Services are included in the Oracle Database and determine optimal
SQL for accessing remote databases. The Services work in tandem with Oracle
Gateways.
Open Database Connectivity
Generic ODBC and OLE DB agents are commonly available for non-Oracle data‐
bases and are provided for the Oracle database by Heterogeneous Services.
Oracle Gateways
Oracle Gateways exist for non-Oracle data stores such as (IBM) Informix, Microsoft
SQL Server, (SAP) Sybase, and Teradata. The DRDA Gateway provides access to
IBM data stores via IBM Distributed Relational Database Architecture (DRDA)
connections.
