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OIC(A) again « Timur Akhmadeev's blog
https://timurakhmadeev.wordpress.com/2013/03/21/oica-again
Timur Akhmadeev's blog. Ignoring hints ». Issues with OICA/OIC ( OPTIMIZER INDEX COST ADJ. Parameters have already been mentioned many times. Recently I’ve noticed one more and I think I didn’t see this case somewhere else on the Internet so I’ll share it. Here’s a simple table T1 holding 1M rows with the indexed column X having 10 distinct values:. The results are expected:. Since the table is around 30K blocks and the data associated with any given value X is spread across all of the table blocks and t...
timurakhmadeev.wordpress.com
Interview with Jonathan Lewis « Timur Akhmadeev's blog
https://timurakhmadeev.wordpress.com/2013/08/05/interview-with-jonathan-lewis
Timur Akhmadeev's blog. OIC(A) again – 2. Transcript of the interview with Jonathan Lewis ». Interview with Jonathan Lewis. If you follow my Twitter. You probably have heard. That Jonathan Lewis visited Moscow in May this year. Thanks to Innova. Jonathan gave a 1-day seminar, and I was one of the lucky people from Russian Oracle community who have been invited to the event. Even more, I was offered to take an interview with Jonathan which was recorded! This entry was written by Timur Akhmadeev. Just got ...
timurakhmadeev.wordpress.com
start_of_group « Timur Akhmadeev's blog
https://timurakhmadeev.wordpress.com/2013/07/21/start_of_group
Timur Akhmadeev's blog. OIC(A) again – 2 ». Those who visit SQL.ru. Often know what the title means. It’s a very simple yet powerful technique to group data which doesn’t seem appropriate for grouping at first sight. Example query comes from this post. And lists all extents in a given tablespace plus free space. So I’m starting with the base query listing used and free extents:. Now here’s the major part of this trick: I need to identify each start of a group of rows which I’m going to assign...Follow an...
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Averages « Timur Akhmadeev's blog
https://timurakhmadeev.wordpress.com/2014/02/20/averages
Timur Akhmadeev's blog. Transcript of the interview with Jonathan Lewis. Hotsos 2016 ». Recently while observing AWR reports, I’ve seen a very good example of how average value hides important pattern. Here is a Workload Comparison section from an AWR diff report (generated with $ORACLE HOME/rdbms/admin/awrddrpt.sql):. Luckily there are other sources of information in AWR, and system metrics. And here is an important detail: 1st period is in red. Compared to the 1st report, is actually showing that spike...
oisene.blogspot.com
Øyvind Isene's Blog: Gather statistics on spatial index
http://oisene.blogspot.com/2015/07/gather-statistics-on-spatial-index.html
Stuff related to the Oracle database (and some more), but not so much about me. Monday, July 27, 2015. Gather statistics on spatial index. When you run dbms stats.gather table stats on tables with spatial indexes or dbms stats.gather index stats directly on the spatial index the routine may return without an error even if no statistics gathering took place. You can verify this by looking at the LAST ANALYZED column in DBA INDEXES:. Select owner,table name from dba tables where table name like 'MDXT %';.
oisene.blogspot.com
Øyvind Isene's Blog: June 2014
http://oisene.blogspot.com/2014_06_01_archive.html
Stuff related to the Oracle database (and some more), but not so much about me. Sunday, June 22, 2014. Some thoughts from last PoC. For the second time I have been involved with a proof of concept (PoC) where testing of an alternative hardware platform was the goal. Common for both PoCs were:. The other option was Exadata. Real Application Testing (RAT) was used to replay production recordings on the new hardware. There is no good substitute for proper understanding. DBAs have heard for many years th...
oisene.blogspot.com
Øyvind Isene's Blog: November 2014
http://oisene.blogspot.com/2014_11_01_archive.html
Stuff related to the Oracle database (and some more), but not so much about me. Monday, November 10, 2014. Use Domains in SQL Developer Data Modeler. How long is an email address? 30 characters should be enough, I thought. And I was right for about three weeks or so until one of the smartest Oracle experts in Europe tried to submit an abstract at our call for paper site. His email address had 32 chars and therefore failed already at registration. A bit embarrassing. Links to this post. The opinions here ...
oisene.blogspot.com
Øyvind Isene's Blog: July 2015
http://oisene.blogspot.com/2015_07_01_archive.html
Stuff related to the Oracle database (and some more), but not so much about me. Monday, July 27, 2015. Gather statistics on spatial index. When you run dbms stats.gather table stats on tables with spatial indexes or dbms stats.gather index stats directly on the spatial index the routine may return without an error even if no statistics gathering took place. You can verify this by looking at the LAST ANALYZED column in DBA INDEXES:. Select owner,table name from dba tables where table name like 'MDXT %';.
oisene.blogspot.com
Øyvind Isene's Blog: March 2014
http://oisene.blogspot.com/2014_03_01_archive.html
Stuff related to the Oracle database (and some more), but not so much about me. Friday, March 28, 2014. 42 Reasons to join me at #OUGN14. Oracle User Group Norway (OUGN) organizes the biggest Oracle user conference in Scandinavia. As of March 28, 341 DBAs, developers, managers, sales people, and more have figured out why. Read on for more reasons if you have not registered yet. This year we are breaking many of our own records, for example we have 66 speakers from 15 different countries. The Java track h...
oisene.blogspot.com
Øyvind Isene's Blog: To a junior DBA
http://oisene.blogspot.com/2015/01/to-junior-dba.html
Stuff related to the Oracle database (and some more), but not so much about me. Saturday, January 31, 2015. To a junior DBA. Have a fire drill once in a while to test your routines and skills. Get some clear policies in place like, how much data are you allowed to lose, and how much time (downtime) do you have to recover your database. Is a phrase that can freak people out, but if you can't lose data, is your system and routines really prepared for that? Make friends and discover that you are not alone&#...