Oracle

SQL monitoring 12.1.0.2 shows adaptive plans

By Franck Pachot . In a previous post, I have described Adaptive Plans. Even if I prefer to show plans with the SQL Monitor active html format, I had to stick with the dbms_xplan for that because SQL(…)

Beyond In-Memory, what’s new in 12.1.0.2 ?

By Franck Pachot . It’s just a patchset. The delivery that is there to stabilize a release with all the bug fixes. But it comes with a lot of new features as well. And not only the one that(…)

Drilling down V$RECOVERY_AREA_USAGE

By Franck Pachot . In a previous post I used X$KCCAGF to get more information about reclaimable archived logs in FRA, because there is a bug in standby (not opened) databases where archivelog deletion policy is ignored. I(…)

Oracle EM agent 12c thread leak on RAC

By Franck Pachot . In a previous post about nproc limit, I wrote that I had to investigate the nproc limit with the number of threads because my Oracle 12c EM agent was having thousands of threads. This(…)

Partial Join Evaluation in Oracle 12c

By Franck Pachot . Do you think that it’s better to write semi-join SQL statements with IN(), EXISTS(), or to do a JOIN? Usually, the optimizer will evaluate the cost and do the transformation for you. And in this(…)

Oracle Parallel Query: Did you use MapReduce for years without knowing it?

By Franck Pachot . I’ve read this morning that MapReduce is dead. The first time I heard about MapReduce was when a software architect proposed to stop writing SQL on Oracle Database and replace it with MapReduce processing.

Linux: how to monitor the nofile limit

By Franck Pachot . In a previous post I explained how to measure the number of processes that are generated when a fork() or clone() call checks the nproc limit. There is another limit in /etc/limits.conf – or(…)

Linux: how to monitor the nproc limit

By Franck Pachot . You probably know about ‘nproc’ limits in Linux which are set in /etc/limits.conf and checked with ‘ulimit -u’. But do you know how to handle the monitoring and be alerted when you’re close the fixed(…)

How to list all Oracle system schemas

By Franck Pachot . Do you want to know which users come with the Oracle Database and which are the ones you have created? This is that not easy, especially prior to Oracle 12c. You know SYS and SYSTEM,(…)

Oracle Exadata – poor optimization for FIRST_ROWS

By Franck Pachot . In a previous blog, I discussed the difference between rownum and row_number(), in particular their behaviour in implicitely adding a first_rows(n) to the optimizer. That reminded me that I forgot to blog about an(…)