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Database Feed

Oracle Database, Oracle 10g, Oracle 11g, Oracle XE, Oracle RAC, Oracle Instant Client, Oracle Data Guard and Oracle Exadata resources, news, and support articles.

New Presentation : On Nested Loop and Hash Join

I have uploaded a new presentation on Nested Loop and Hash Joins. This is based on the "Nested Loops and Consistent Gets" case study.


Backups are forever

You should save this link in your bookmarks, for the next time you accidentally remove your database’s online redologs or overwrite some ASM disks:


Cache buffers chains latch contention troubleshooting using latchprofx.sql example

Laurent Demaret has written a good article about how he systematically troubleshooted cache buffers chains latch contention, starting from wait interface and drilling down into details with my latchprofx tool:

Please Vote for Oracle OpenWorld Suggest-a-Session on Oracle Mix

Back by popular demand, Oracle OpenWorld Suggest-a-Session on Oracle Mix

Please vote for my session (Administration of Automatic Diagnostic Repository )for the Oracle OpenWorld 2011

To vote, click here.

Getting the right statistics

Continuing with the post titled "Nested Loops and Consistent Gets" earlier today, what is the Execution Plan with statistics on more columns ?

SQL> exec dbms_stats.gather_table_stats('','TRANSACTIONS',estimate_percent=>100,granularity=>'ALL',-
> method_opt=>'FOR COLUMNS COUNTRY_CD SIZE 250, PRODUCT_CD SIZE 250, TXN_ID SIZE 250 ',cascade=>TRUE);

PL/SQL procedure successfully completed.


Try to manage a OVM server once managed by another OVM manager.

Try to manage a OVM server once managed by another OVM manager.


Embedded in each server are records of its current affiliation. These records will prevent the server from being registered again.

When to Rebuild Secondary Indexes on Index-Organized Tables?

For my new book on Oracle indexing, I’d like to provide guidance on detecting when the block references in a secondary index on an index-organized table (IOT) need to be updated. All that I could find using my second brain were unsubstantiated claims that a secondary index should be rebuilt when PCT_DIRECT_ACCESS falls below 30. [...]

Nested Loop and Consistent Gets

DBAs with a few years of experience and/or having read some material on performance tuning know that eliminating physical reads and achieving a high buffer cache hit ratio isn't necessarily a tuning goal.
Some DBAs have accepted the idea that, rather than physical reads, they should concentrate on logical reads -- consistent gets in case of queries.
But ...... there really is no "absolutely correct optimization target". Everything is relative.

Monitoring Exadata Cell using some Views

When we have Exadata, we might ask some questions, what dynamic V$ views we can use for monitoring?
V$CELL - to display Exadata Cell Identification.

SQL> desc v$cell
Name Null? Type
----------------------------------------- -------- ----------------------------

CELL_PATH - IP addresses of the cell.

Real-World Solutions for Developing High-Quality PHP Frameworks and Applications by Sebastian Bergmann, Stefan Priebsch

PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. PHP is the popular programming language to produce dynamic web pages. You can see many applications/frameworks what were developed by PHP programming language.

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