Posted by Riyaj Shamsudeen on January 28, 2017
I will be speaking about the following topics in Rocky Mountain Oracle User group Training days (RMOUG, Denver) February 7-9, 2017.
Come to my presentations and say Hi to me 🙂
1. RAC Cache Fusion Internals and Performance Tuning RAC Wait Events – Tuesday 3:15PM to 5:15PM
2. Index and Redo Internals – Wednesday 4-5PM
3. Database In-Memory Internals – Thursday 11:15-12:15PM
RMOUG training days 2017
Here are the scripts and presentations as promised 🙂 Of course, no implied or explicit warranty.
index_and_redo_internals scripts zip
Disclaimer: These are my opinions based upon research and data, it doesn’t reflect the views of my employer.
Posted in 12c, inmemory, Oracle database internals, Performance tuning, Presentations, RAC | Tagged: oracle performance, RAC performance, RAC presentations, RAC training, rmoug, rmoug 2017 | Leave a Comment »
Posted by Riyaj Shamsudeen on May 21, 2016
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.
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.
SID PID EVENT USERNAME OSUSER STATE WAIT_TIME WIS P1_P2_P3_TEXT
------ ---------- ------------------------------ ---------- ---------- ------------------- --------- ----- ----------------------------------------
276 12445 library cache lock TST_USR test WAITING 0 1 handle address 399021346904-lock address
288 12449 library cache lock TST_USR test WAITING 0 4 handle address 399021346904-lock address
303 12453 library cache lock TST_USR test WAITING 0 4 handle address 399021346904-lock address
315 12457 library cache lock TST_USR test WAITING 0 4 handle address 399021346904-lock address
Posted in 12c, inmemory, Oracle database internals, Performance tuning, RAC | Tagged: $BUILD$, inmemory internals, kglLockWait, library cache lock, oracle performance, pstack, x$kgllk, x$kglob | 5 Comments »
Posted by Riyaj Shamsudeen on April 15, 2015
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.
Posted in in-memory, inmemory, Performance tuning, Presentations | Tagged: dtrace, oracle performance, perf record, perf tool, pstack, truss | Leave a Comment »
Posted by Riyaj Shamsudeen on March 25, 2015
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.
Posted in inmemory, Oracle database internals, Performance tuning, Presentations, RAC | Tagged: collaborate 2015, in-memory internals, ioug, presentations, strace, truss | Leave a Comment »
Posted by Riyaj Shamsudeen on October 6, 2014
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.
- @snapper.sql out,gather=stw 600 10 “select sid from v$session where program like ‘%W00%'”
- Perf tool : perf record -F 99 -u oracle -g sleep 3600
Posted in 12c, in-memory, inmemory, Oracle database internals, Performance tuning, Presentations | Tagged: 12c in-memory, in-memory, kdzu, perf record, perf report, pre-population cpu time, pre-population speed, snapper | Leave a Comment »
Posted by Riyaj Shamsudeen on September 26, 2014
Many Oaktable members are planning to talk about deep technical topics in Oaktable world 2014. Looking at the agenda, I am excited, so many deep topics are planned. I will be talking about in-memory internals on Monday morning at 9AM, 9/29/2014, right after Mogens’ Keynote speech. You can find all details here: Oaktable world 2014. I will post my presentation slides after the presentation.
Start your open world week presentation with mine :). Sorry, no beers planned at that time, it is 9AM, after all!
Thanks for attending my presentation at Oaktable World 2014. You can download the slides : In-memory_internals.pdf.
Also, our book Expert Oracle RAC 12c has been translated to Chinese language. You can find details about that book in one of the translator’s blog: Alex lizx.
Posted in 12c, in-memory, inmemory | Tagged: in-memory, oaktable world 2014, presentations | Leave a Comment »
Posted by Riyaj Shamsudeen on September 11, 2014
I enabled an huge 70G table for inmemory population, I expected the inmemory population to take a while, but the population didn’t complete even after letting it run for a day. Why?
Initial review of the server shows no issues, no resource starvation. This must be a problem with Oracle processes itself. I started digging further, and ASH data shows that in numerous samples the process was seen reading block using single block I/I calls. Also object_id matches with the table I was trying to populate.
select * from (
select start_time, end_time, sql_id,event, current_obj#, cnt_on_cpu + cnt_waiting tot_cnt,
rank () over ( order by (cnt_on_cpu + cnt_waiting) desc ) rnk
sum(decode(session_state,'ON CPU',1,0)) cnt_on_cpu,
first_value(sample_time) over( order by sample_time ) start_time,
last_value(sample_time) over( order by sample_time
rows between unbounded preceding and unbounded following ) end_time,
sql_id,event, session_state, current_obj#
(select * from v$active_session_history ash where session_id= &&sid and session_serial#=&&serial_number)
group by sql_id, event, current_obj#
START_TIME END_TIME SQL_ID EVENT CURRENT_OBJ# TOT_CNT RNK
------------------------- ------------------------- ------------- ------------------------------ ------------ ---------- ----------
18-AUG-14 08.42.03.702 AM 18-AUG-14 09.02.06.463 AM db file sequential read 168967 990 1
168967 156 2
direct path read 168967 50 3
bdwtqttka2w2y -1 3 4
bdwtqttka2w2y direct path read 168967 1 5
24uqc4aqrhdrs 168967 1 5
-1 1 5
Read the rest of this entry »
Posted in 12c, inmemory | Tagged: 12c inmemory, inmemory internals | 3 Comments »