In an Oracle heterogeneous
distributed database system at
least one of the database systems is a non-Oracle system. Oracle open gateways provides access to a
non-oracle database from a oracle server which uses a database link to access
data or to execute remote procedures in a non-oracle system. The open gateway
features are as follows:
- Distributed Transactions. A
transaction can span both Oracle and non-Oracle systems, while still
guaranteeing, through Oracle's two phase commit mechanism, that changes
are either all committed or all rolled back.
- Transparent
SQL access. Integrate data from
non-Oracle systems into the Oracle environment as if the data is stored in
one single, local database. SQL statements issued by the application are
transparently transformed into SQL statement understood by the non-Oracle
system.
- Procedural
Access. Procedural systems, like
messaging and queuing systems, are accessed from an Oracle8 server using
PL/SQL remote procedure calls.
- Pass-through
SQL. Optionally, application
programmers can directly access a non-Oracle system from an Oracle
application using the non-Oracle system's SQL dialect.
- Accessing
stored procedures. Stored
procedures in SQL-based non-Oracle systems are accessed as if they were
PL/SQL remote procedures.
- National
Language Support. Gateways
support multi-byte character sets, and translate character sets between a
non-Oracle system and the Oracle8 server.
- Global
query optimization.
Cardinality and indexes on tables at the non-Oracle system are taken into
account by the Oracle8 query optimizer and decomposed to produce efficient
SQL statements to be executed at the non-Oracle system.
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