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Have you ever wondered who was responsible
for changing the salary table to zero out your fellow DBA's
pay or entering all the new prices in the online store without
using the decimal point? Would it be useful to locate the
offending SQL statement and be provided with SQL required
to correct it? This is a great tool for undoing a single erroneous
transaction without having to go through a database restore.
Every change made to an Oracle database by
default generates undo and redo information which is accumulated
in Oracle redo log files. Oracle9i LogMiner is an integrated
feature of the Oracle9i Database that provides DBA's and auditors
with the infrastructure required for relational access to
Oracle's redo stream.
Some significant enhancements to LogMiner
for Oracle9i generated log files include:
- A new LogMiner Viewer GUI in addition
to the command line interface
- The ability to translate DML associated
with Index Clusters
- The ability to mine for changes by value
- Support for chained and migrated rows
- Support for direct path inserts
- Ability to use an online dictionary
- Ability to extract the data dictionary
into the redo log files to seamlessly integrate DDL changes
- DDL statement tracking
- Ability to skip log corruptions
- Ability to specify that only committed
transactions be displayed
- Generate SQL_REDO and SQL_UNDO with primary
key information to help the DBA undo changes
The online data dictionary can be extracted into
the redo log stream. This enables off-line analysis and provides
a snapshot of the data dictionary that matches the database
objects in logs created at that time. When mining logs in the
same database that generated it, the user can choose to use
the online data dictionary for SQL reconstruction and internal
identifier to name mapping which would otherwise be a manual
process.
The user can group DML statements into transactions
with a COMMITTED_DATA_ONLY option which directs LogMiner to
group DML statements into complete transactions. Only committed
transactions will be returned in the commit SCN order. When
the DDL_DICT_TRACKING option is enabled and LogMiner is run
in the context of an open database, it will automatically
apply DDL statements executed in the original redo stream
to its internal dictionary. This enables correct reconstruction
of correct SQL statements on tables whose definition has been
altered or were missing when the original dictionary dump
was captured. LogMiner automatically versions the metadata
kept in the database.
New DDL statements have been added to Oracle's
vocabulary to allow for logging of additional column values
in case of updates. The extra information can be used either
to identify the updated row logically or to capture a before-row
image. This allows a DBA or auditor to use the additional
column information to construct more complete statements to
undo changes or to create SQL statements for applying to a
different databases.
A powerful new capability allows for queries
that can filter out rows based on actual data values of the
columns updated. For instance it is possible to write a query
for a postal database that identifies all lottery winners
who moved to 90210 after making it big in Redwood Shores.
LogMiner improves data availability by providing
a window into all changes made to a database. It enables auditing
of database changes and reduces the time and effort needed
for data recovery.
More Info
Oracle9i
Database Daily Features
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