Infrastructure at your Service
In a recent project we migrated an Oracle database previously running on 12.1.0.2 on an Oracle Database Appliance to an Exadata X8 with DB version 19.7. Shortly after the migration a merge-statement (upsert) failed with an ORA-07445: exception encountered: core dump [kdu_close()+107] [SIGSEGV] [ADDR:0xE0] [PC:0x1276AE6B] [Address not mapped to object] [] The stack looked as follows: kdu_close – updThreePhaseExe – upsexe – opiexe – kpoal8 – opiodr – ttcpip – opitsk – opiino – opiodr…
By Franck Pachot . NoSQL provides an API that is much simpler than SQL. And one advantage of it is that users cannot exceed a defined amount of resources in one call. You can read this in Alex DeBrie article https://www.alexdebrie.com/posts/dynamodb-no-bad-queries/#relational-queries-are-unbounded which I take as a base for some of my “Myth of NoSQL vs RDBMS” posts because he explains very well how SQL and NoSQL are perceived by the users. But this idea of…
There are several methods to find out where time is spent in an execution plan of a query running in an Oracle database. Classical methods like SQL Trace and running a formatter tool like tkprof on the raw trace, or newer methods like SQL Monitor (when the Tuning Pack has been licensed) or running a query with the GATHER_PLAN_STATISTICS-hint (or with statistics_level=all set in the session) and then using DBMS_XPLAN.DISPLAY_CURSOR(format=>’ALLSTATS LAST’). However, what I often…
By Franck Pachot . Announced by Larry Ellison last week, here it is: the Autonomous Data Guard. You can try it, unfortunately not on the Free Tier. First you create an Autonomous Database (ATP or ADW) and then you enable Autonomous Data Guard. You know that “Autonomous” is the marketing brand for the services that automate a lot of things, sometimes based on features that are in Oracle Database for a long time. So let’s…
By Franck Pachot . The FETCH FIRST … ROWS ONLY syntax arrived in Oracle 12c and is much more convenient than using a subquery with ‘ORDER BY’ wrapped in a “WHERE ROWNUM < …” around it. But as I mentioned in a previous post it required the FIRST_ROWS() hint to get correct estimations. In SQL you don’t want to overload your code for performance, right? The RDBMS optimizer does the job for you. This was…
As you probably heard if you weren’t in an underground bunker for the past 2 years, Oracle changed the licensing of the Oracle JDK. If you want to read more about it, there is a good FAQ here. This obviously had some important repercussions everywhere and Documentum wasn’t exempted. I would have a lot to say about the way OpenText tried to adapt since Documentum 16.4 (and kind of failed) but that’s not really the…
By Franck Pachot . This is a demo about Oracle ACFS snapshots, and how to understand the used and free space, as displayed by “df”, when there are modifications in the base parent or the snapshot children. The important concept to understand is that, when you take a snapshot, any modification to the child or parent will [[email protected] ~]$ asmcmd lsdg DATAC1 State Type Rebal Sector Logical_Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Voting_files…
I had the opportunity to participate to POUG day 1 and wanted through this blog to share some of my feedback on the interesting sessions I could follow. First of all, I would like to mention the great introduction done by the staff team and the great organization. POUG staff team could adapt to the coronavirus situation and organized excellent POUG virtual days. Well done!
By Franck Pachot . I had a few questions about the Oracle ACE program recently and I thought about putting some answers there. Of course, that’s only my point of view, there’s an official web page: https://www.oracle.com/technetwork/community/oracle-ace/index.html The program is flexible and open, with a large diversity of people, technologies, contributions, levels,… Then rather than explaining what it is, which would be limiting, I’ll rather tell you… what it is not. It is not a…
By Franck Pachot . I originally wrote this as a comment on the following post that you may find on internet: https://www.2ndquadrant.com/en/blog/oracle-to-postgresql-reasons-to-migrate/ but my comment was not published (many links in it… I suppose it has been flagged as spam?) so I put it there. You should never take any decision on what you read on the internet without verifying. It is totally valid to consider a move to Open Source databases, but doing it…
