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A backup is a representative copy of data. This copy can include important parts of a database such as the control file, redo logs, and datafiles. A backup protects data from application error and acts as a safeguard against unexpected data loss, by providing a way to restore original data. Backups are divided into physical [...]
Written by admin on November 30th, 2010 with comments disabled.
Read more articles on Oracle Backup and Recovery.
Oracle8i and later has a great feature that stores information on long-running queries currently active in the V$SESSION_LONGOPS view. The following example shows the results of a query against V$SESSION_LONGOPS: SELECT username, sql_text, sofar, totalwork, units FROM v$sql, v$session_longops WHERE sql_address=address AND sql_hash_value=hash_value ORDER BY address, hash_value, child_number HROA select count(*) from winners w1, winners_backup [...]
Written by admin on November 23rd, 2010 with comments disabled.
Read more articles on Oracle Tuning.
An inline view is a statement in the FROM-clause of another SELECT statement. In-line views are commonly used simplify complex queries by removing join operations and condensing several separate queries into a single query. This feature was introduced in Oracle 7.2.An example of inline view is given blow SELECT * FROM (select dept_no, count(*) emp_count [...]
Written by admin on November 8th, 2010 with no comments.
Read more articles on SQL tutorials.
The ROWNUM pseudo column returns the row number of the record. This is a logical number, determined at the time a query is run. As such, a delete or insert can cause a different ROWNUM assignment. Row numbers do not stick to a particular record, so never rely on them as you would a physical [...]
Written by admin on November 4th, 2010 with no comments.
Read more articles on SQL tutorials.