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oracle performance

library cache lock on BUILD$ object

I was testing an application performance in 12c, and one job was constantly running slower than 11g. This post is to detail the steps. I hope the steps would be useful if you encounter similar issue.

Problem

In an one hour period, over 90% of the DB time spent on waiting for library cache lock waits. Upon investigation, one statement was suffering from excessive waits for ‘library cache lock’ event. We recreated the problem and investigated it further to understand the issue.

Following is the output of wait_details_rac.sql script (that I will upload here) and there are many PX query servers are waiting for ‘library cache lock’ wait event.

OTNYathra2016

Over the last many years, some of you have invited me to attend conferences in India, and talk about Oracle RAC and performance. I have not had an opportunity to make it to conferences in India, until now:)

I am excited to announce that I will be participating in OTN sponsored Oracle ACE Director’s tour in India (April 23rd to May 2nd 2016), and presenting ( with deep dive demos ) about RAC, performance, and in-memory. This is a golden opportunity for you to learn some of the internal stuff that I talk about in my class too.

Refer http://otnyathra.com for further details.

OOUG RAC day presentation files and scripts

Thanks for coming to my presentations in RAC day at Dublin, Ohio. Please find the presentation files below. Hopefully, I will get video files and upload that here too.

OOUG presentation files and scripts

md5 checksum of the zip file is:

$md5sum ooug_2015_pdf.zip
df8bdcbc02926e5bbd721514b473bf16  ooug_2015_pdf.zip

RAC day with Ohio Oracle User Group

I will be talking about RAC and performance in-depth, with lots of demos, in a RAC day training with Ohio Oracle User group on Nov 16,2015 Monday. Venue for the presentation is Dublin, Ohio.

Agenda for the day:

NYOUG Session: Latches Demystified

Thank you all those who came to attend my session on demystifying latches at New York Oracle Users Group in Manhattan. I hope you found the session useful and enjoyable.

Whitepaper: Oracle Database 11g and 12c Consolidation and Workload Scalability with EMC XtremIO 3.0

This is a just a quick blog post to direct readers to the best Oracle-related paper detailing the value EMC XtremIO brings to Oracle Database use cases.  I’ve been looking forward to the availability of this paper for quite some time as I supported (minimally, really) the EMC Global Solutions Engineering group in this effort. They really did a great job with this testing! I highly recommend this paper for readers who are interested in:

Demos do fail.

I am an ardent believer of “show me how it works” principle and usually, I have demos in my presentation. So, I was presenting “Tools for advanced debugging in Solaris and Linux” with demos in IOUG Collaborate 2015 in Las Vegas on April 13 and my souped-up laptop (with 32G of memory, SSD drives, and an high end video processor etc ) was not responding when I tried to access folder to open my presentation files.

Sometimes, demos do fail. At least, I managed to complete the demos with zero slides:-) Apologies to the audience for my R-rated rants about laptop issues.

You can download presentations files from the links below.

Cache Buffer Chains Demystified

You must have seen sessions waiting on the event “latch: cache buffers chains” from time to time. If you ever wondered what this means and how you can reduce time spent on it, read on.

OOW14 Session: SQL Tuning Without Trying

Many thanks to all those who attended my session "SQL Tuning without Trying" at Oracle Open World 2014 #oow14. I hope you found the session useful.

If you want to download the slide deck, here it is. As always, I would really, really like to hear from you.

SLOB Physical I/O Randomness. How Random Is Random? Random!

I recently read a blog post by Kyle Hailey regarding some lack of randomness he detected in the Orion I/O generator tool. Feel free to read Kyle’s post but in short he used dtrace to detect Orion was obliterating a very dense subset of the 96GB file Orion was accessing.