It is well known that the entire shared pool can be flushed with a simple ALTER SYSTEM statement. SQL> ALTER SYSTEM FLUSH SHARED_POOL;System altered. What if the execution plan of a single SQL statement has to be invalidated or flushed out of the shared pool so the subsequent query execution forces a hard parse on that SQL statement. Oracle 11g introduced a new procedure called PURGE in the DBMS_SHARED_POOL package to flush a specific object such as a cursor, package, sequence, trigger, .. out of the object library cache. The syntax for the...
Monday, 31 May 2010
Sunday, 23 May 2010
(Original post is at blogs.sun.com at:http://blogs.sun.com/mandalika/entry/oracle_database_say_i_no) .. unless you are working with a database that is largely read-only or if the new index is supposed to be fixing a critical performance issue with no side effect(s).Two topics covered in this blog entry with plenty of simple examples: Why creating new indexes on a heavily modified table may not be a good idea? and How to identify unused indexes?Read on.Indexes are double-edged swords that may improve the performance of targeted queries, but in some...
Monday, 10 May 2010
(Originally posted on 12/09/2009. This blog posted will be updated as new compositions come along.)For the past couple of weeks I have had fun playing with Apple's GarageBand. It is a nice piece of software with intuitive user interface and tons of free & ready-to-use music loops. It only took a couple of tries and about 6 hours to produce my first ever mixed tune with software of any kind. The second one just took two hours as my main focus...
Friday, 7 May 2010
Monday, 3 May 2010
(Originally posted on blogs.sun.com at http://blogs.sun.com/mandalika/entry/oracle_11g_r1_poor_data)Symptom(s)Data Pump Export utility, expdp, performs well with non-partitioned tables, but exhibits extreme poor performance when exporting objects from a partitioned table of similar size. In some cases the degradation can be as high as 3X or worse.SQL traces may show that much of the time is being spent in a SQL statement that is similar to:UPDATE "schema"."TABLE" mtu SET mtu.base_process_order = NVL((SELECT mts1.process_order FROM "schema"."TABLE"...
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