Commit scalability

I am learning about how well commits scale on Oracle 11.2 and so far they seem to scale surprisingly well.

I’ve looked at two waits – log file parallel write and log file sync.  Based on documents I’ve read on Oracle’s support site log file parallel write represents the time it takes to do one write to the redo logs.  For mirrored redo logs the log file parallel write time includes the (more...)

Passed OCP 12c test

Well, I finally passed the Oracle Certified Professional (OCP) 12c upgrade exam, 1Z0-060.  I got 86% right on the new features section and 78% correct on the general DBA section.  So, that means I missed roughly 7 questions on each section which was more than I expected because I felt good about all of my answers.

I’m happy with the three resources I used which are:

  1. Self Test software – $99
  2. Matthew Morris (more...)

Query with new plan

I came up with a simple query that shows a running SQL executing a different plan than what it had in the past.  Here is the query:

-- show currently executing sqls that have history
-- but who have never run with the current plan
-- joins v$session to v$sql to get plan_hash_value of 
-- executing sql.
-- queries dba_hist_sqlstat for previously used values 
-- of plan_hash_value.
-- only reports queries that have an  (more...)

12c Threaded Execution Test

I did a quick check of some facts I’m studying about Oracle 12c and its new threaded execution mode.  I set this parameter:

alter system set THREADED_EXECUTION=true scope=spfile;

I had to connect SYS as SYSDBA with a password to get the system to bounce.

Then it had these processes only:

oracle    1854     1  0 09:17 ?        00:00:00 ora_pmon_orcl
oracle    1856     1  0 09:17 ?        00:00:00 ora_psp0_orcl
oracle    1858     1  2 09:17 ?        00:00:00 ora_vktm_orcl
 (more...)

Finished first pass through Alapati 12c OCP upgrade book

I just finished reading Sam Alapati’s 12c OCP upgrade book for the first time and I really like it because of the content that it covered which I hadn’t discovered through my study of the Oracle manuals.  Also, it did a good job explaining some things that Oracle’s manuals left unclear.

After reading each chapter I took the end of chapter test and got between 60% and 75% of the questions right.  Next (more...)

Used Delphix to quickly recover ten production tables

Yesterday I used Delphix to quickly recover ten production tables that had accidentally been emptied over the weekend.  We knew that at a certain time on Saturday the tables were fully populated and after that some batch processing wrecked them so we created a new virtual database which was a clone of production as of the date and time just before the problem occurred.  We could have accomplished the same task using RMAN (more...)

Sam Alapati’s 12c OCP upgrade book includes test software with key DBA skills

Sweet!  I just installed the software from the CD that came with Sam Alapati’s book related to the OCP 12c upgrade exam and found that it has questions related to the key DBA skills section of the test.  Now I feel good about my test preparation materials.  The first time I took the test I didn’t have this degree of guidance on what to study, especially on the key DBA skills section.

(more...)

Bought Matthew Morris’ OCP 12c upgrade book for Key DBA Skills section

I haven’t even started on Sam Alapati’s OCP book but I realized today that Matthew Morris’s OCP 12c upgrade book has an outline of the Key DBA Skills section of the OCP exam and that is what I need most.  I was two questions away on that section when I took the test the first time and I need to make sure I’m studying the right things.  After I got back to the (more...)

Limits of SQL Optimization Toastmasters Talk

I think I’m done with the script for my Toastmaster’s talk: pdf

It’s Toastmaster’s talk 3 “Get to the Point” so I’m trying to do a 5-7 minute talk that focuses on how Oracle’s SQL optimizer sometimes chooses a slow plan.  It’s tough to say anything meaningful in 7 minutes and I’m not using any kind of slides so I have to describe everything verbally.

But, it’s a topic I’m passionate about so I (more...)

Adding an outline hint to a PS/Query

I just finished working with a coworker on speeding up a PS/Query.  It was running well in a development environment but not in production.  I tried to find a simple hint or two to make production run like development but didn’t have any luck.  Then I remembered that my script to get a query’s plan prints out a full set of outline hints like this:

  /*+
      BEGIN_OUTLINE_DATA
      USE_HASH_AGGREGATION(@"SEL$E903463E")
       (more...)