If your Oracle Database fits into the buffer cache, we will put all segments into it now upon access – no more direct reads:
SQL> connect / as sysdba Connected. SQL> select banner from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 12c Enterprise Edition Release 188.8.131.52.0 - 64bit Production PL/SQL Release 184.108.40.206.0 - Production CORE 220.127.116.11.0 Production TNS for Linux: Version 18.104.22.168.0 - Production NLSRTL Version 22.214.171.124.0 - Production SQL> select sum(bytes)/1024/1024 as mb from v$datafile; MB ---------- 1424 SQL> select current_size from v$buffer_pool; CURRENT_SIZE ------------ 1872
The requirements are met here, I don’t need to force anything:
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.
md5 checksum of the zip file is:
$md5sum ooug_2015_pdf.zip df8bdcbc02926e5bbd721514b473bf16 ooug_2015_pdf.zip
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:
08:00a – 09:00: Registration / Breakfast 09:00a – 09:15: Announcements -Introduction of the speaker 09:15a – 10:30: Underpinning for Oracle RAC and Clusterware 10:30a – 10:45: Break 10:45a – 11:45: RAC cache fusion internals 11:45a – 01:00: Lunch 01:00p – 02:00: RAC Performance tuning Part 1 – Wait events and object tuning 02:00p – 02:15: Break 02:15p – 03:30: RAC performance tuning Part 2 – locks, library cache locks etc. 03:30p – 03:45: Member Announcements, Gift Drawings
Please RSVP to the co-ordinators so that you will have a seat :)
There is a new auditing architecture in place with Oracle Database 12c, called Unified Auditing. Why would you want to use it? Because it has significantly less performance impact than the old approach. We buffer now audit records in the SGA and write them asynchronously to disk, that’s the trick.
Other benefits of the new approach are that we have now one centralized way (and one syntax also) to deal with all the various auditing features that have been introduced over time, like Fine Grained Auditing etc. But the key improvement in my opinion is the reduced performance impact, because that was often hurting customers in the past. Let’s see it in action! First, I will record a baseline without any auditing:
After invisible indexes got introduced in 11g, they have now been enhanced in 12c: You can have multiple indexes on the same set of columns with that feature. Why would you want to use that? Actually, this is always the first question I ask when I see a new feature – sometimes it’s really hard to answer :-)
Here, a plausible use case could be that you expect a new index on the same column to be an improvement over the existing old index, but you are not 100% sure. So instead of just dropping the old index, you make it invisible first to see the outcome:
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.
I will be presenting two topics in IOUG Collaborate 2015 in Vegas. Use the show planner and add my presentations to your schedule :)
Session #189: April 13 Monday 9:15 to 10:15AM Topic: Oracle Database 12c In-Memory Internals. Room Palm B
Session #145: April 13 Monday 12:45PM-1:45PM Topic: Tools and Techniques for Advanced Debugging in Solaris & Linux (mostly live demo). Room Palm B.
I finally got around preparing another part of the XPLAN_ASH video tutorial.
This part is about the main funcationality of XPLAN_ASH: SQL statement execution analysis using Active Session History and Real-Time SQL Monitoring.
In this video tutorial I'll explain what the output of XPLAN_ASH is supposed to mean when using the Active Session History functionality of the script. Before diving into the details of the script output using sample reports I provide some overview and introduction in this part that hopefully makes it simpler to understand how the output is organized and what it is supposed to mean.
This is the initial, general introduction part. More parts to follow.
While presenting at Oaktable World 2014 in San Fransisco, I discussed the in-memory pre-population speed and indicated that it takes about 30 minutes to 1 hour to load ~300GB of tables. Someone asked me “Why?” and that was a fair question. So, I profiled the in-memory pre-population at startup.
I profiled all in-memory worker sessions using Tanel’s snapper script and also profiled the processes in OS using Linux perf tool with 99Hz sample rate. As there is no other activity in the database server, it is okay to sample everything in the server. Snapper output will indicate where the time is spent; if the time is spent executing in CPU, then the perf report output will tell us the function call stack executing at that CPU cycle. Data from these two profiling methods will help us to understand the root cause of slowness.
I have been testing the inmemory column store product extensively and the product is performing well for our workload. However, I learnt a bit more about inmemory column store and I will be blogging a few them here. BTW, I will be talking about internals of inmemory in Oaktable world presentation, if you are in the open world 2014, you can come and see my talk: http://www.oraclerealworld.com/oaktable-world/agenda/