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February 2014

Dynamic Resource Mastering in 12c

I blogged about Dynamic Resource Mastering (DRM) in RAC here . DRM freezes the global resources during the reconfiguration event and no new resources can be allocated during the reconfiguration. This freeze has a dramatic effect of inducing huge amount of waits for gc buffer busy [acquire|release] events and other gcs drm freeze release, gcs remaster events. In database version 12c, DRM has been improved further.

A major improvement I see is that not all resources are frozen at any time. Essentially, resources are broken down in to partitions and only a resource partition is frozen. This improvement should decrease the impact of DRM related waits tremendously.

LMON Trace file

Empty Hash

A little while ago I highlighted a special case with the MINUS operator (that one of the commentators extended to include the INTERSECT operator) relating to the way the second subquery would take place even if the first subquery produced no rows. I’ve since had an email from an Oracle employee letting me know that the developers looked at this case and decided that it wasn’t feasible to address it because – taking a wider view point – if the query were to run parallel they would need a mechanism that allowed some synchronisation between slaves so that every slave could find out that none of the slaves had received no rows from the first subquery, and this was going to lead to hanging problems.

The New Chapter

Today is my last day at Enkitec and I look back on a whirlwind two years.  As many people know, I never seem to stop moving, (I hear my mother’s voice from when I was a small child saying, “Kellyn, sit down!  Kellyn, don’t climb!  Please, sit still!” :))  Nope, still doesn’t work, but I also never seem to stop growing and it’s time to take that next step in my career.

GITHUB_UTL Roundup and status.

As a roundup, here is a list of all the blog entries I've done so far on the github_utl package. The project was fun, and I got to do a lot of github things, I had not done before. The reason that I even started out with github, was of course because of an incident :). A couple of months back I lost my primary and backup harddrive within an hour ... Bummer. So I lost one specific project I had been working on for close to 1 and a half years. So then I decided that all my code, from there on, should always be pushed to the cloud. The reason I chose GitHub, was simply because I had just downloaded another project from there, and it seemed easy to integrate into the OS using their API's .... read more on my blog

GITHUB_UTL Tutorial 10: Even more data from github in sqlplus!

More on selecting data directly from your github repository, this time. So one of the things I have done since my last post, was replacing and refactoring the code that fetches data from the github api. This change has made it even more easy to get information displayed directly in sqlplus. What this also means though, is that you have to re install the entire github schema. But I have created an easy single install script, so simply log on as sys and execute the install.sql from the latest release, and you should be up and running in no time. So this time I will show you some of the selects that you can run inside of oracle to query your github repository.

GITHUB_UTL Tutorial 10: Even more data from github in sqlplus!

More on selecting data directly from your github repository, this time. So one of the things I have done since my last post, was replacing and refactoring the code that fetches data from the github api. This change has made it even more easy to get information displayed directly in sqlplus. What this also means though, is that you have to re install the entire github schema. But I have created an easy single install script, so simply log on as sys and execute the install.sql from the latest release, and you should be up and running in no time. So this time I will show you some of the selects that you can run inside of oracle to query your github repository.

GITHUB_UTL Roundup and status.

As a roundup, here is a list of all the blog entries I've done so far on the github_utl package. The project was fun, and I got to do a lot of github things, I had not done before. The reason that I even started out with github, was of course because of an incident :). A couple of months back I lost my primary and backup harddrive within an hour ... Bummer. So I lost one specific project I had been working on for close to 1 and a half years. So then I decided that all my code, from there on, should always be pushed to the cloud. The reason I chose GitHub, was simply because I had just downloaded another project from there, and it seemed easy to integrate into the OS using their API's.

OTN Yathra 2014 : Bangalore

Yesterday’s flight to Bangalore was pretty quick, about 80 minutes if I remember correctly. We landed and were picked up by a car from the hotel. We were told the traffic would be terrible in Bangalore, but it wasn’t too bad. Debra managed to keep her eyes open for much of the journey. There were also a lot fewer car horns in comparison to Hyderabad. :)

The Marriott in Bangalore is very swish indeed and of course it has a buffet for dinner! :) I slept OK, but felt quite tired this morning. I think the events of the week are starting to get to me…

Investigating the wait interface via gdb.

For some time now, I am using gdb to trace the inner working of the Oracle database. The reason for using gdb instead of systemtap or Oracle’s dtrace is the lack of user-level tracing with Linux. I am using this on Linux because most of my work is happening on Linux.

In order to see the same information with gdb on the system calls of Oracle as strace, there’s the Oracle debug info repository. This requires a bit of explanation. When strace is used on a process doing IO that Oracle executes asynchronous, the IO calls as seen with strace look something like this:

Modify Primary Key Using Index (Learning To Fly)

One of the things I love about working with Oracle Database technologies is that there’s just so much one can learn. I make it an active goal of mine to try to learn something new at work each and every day, no matter how big or small. One of these days, I might blog about a presentation I put together […]