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Oracle, like other RDBMS', has the ability to import and export databases.
In Oracle10g this system was significantly overhauled and dubbed "Data Pump".
More can be found about this in the Oracle Database Utilities manual.
Data Pump provides the ability to export in several modes, including Full Export,
Schema, Table, Tablespace, and Transportable Tablespace. Exports are "logical
backups", which means the essence of the instance is exported but not the
frame work.
As an SA, exports feel like a real "pack your shit and go" operation.
Think of leaving an office, you don't take the desks or drawers (tablespaces,
control files, etc), you just empty the contents into a big container (dump file)
and leave. The result of an export is a dump file. The file
is binary and effectivly just contains a pile of INSERT statements that
when imported updates the instance. Because of this you can't import
a dump without a database instance ready to accept it, just as you
can't unpack your stuff into a new office unless it has a desk and drawers similar
to the one you just left. Therefore you can't
really look at an export as a serious backup method. It's a great way
to cover your ass or to move data from one place to another, but it's
not much diffrent than just writting a PERL or PL/SQL script to output
every table into a flat file and then using SQL*Loader to CREATE and INSERT
everything back into tables. "Recovering" a database would invole
creating a new instance of the database from scratch (using dbca for
instance) and then importing into that new instance.
With the limits of Data Pump exports understood, there are some advantages
to exports. Because you are importing data into an existing instance you
can easily move tables, tablespaces, schemas, etc into other databases.
Furthermore, because the data is fairly generic, it provides a solid method
of migrating from one version or Oracle to another (if needbe). I've seen
several DBAs take exports just before applying major patches, just as a
failsafe.
Subsections
Next: The Export
Up: The Cuddletech SAs Guide
Previous: Loading SYSLOG into a
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2005-02-10