Oracle

fritshoogland's picture

Reading Oracle memory dumps

Every DBA working with the Oracle database must have seen memory dumps in tracefiles. It is present in ORA-600 (internal error) ORA-7445 (operating system error), system state dumps, process state dumps and a lot of other dumps.

This is how it looks likes:

dbakevlar's picture

EM12c and the Optimizer Statistics Console

Today we’re going to review another great feature in the EM12c that you may not have realized was available.  Once logged into a database target, click on the Performance menu and navigate to the Optimizer Statistics Console:

fritshoogland's picture

Oracle database operating system memory allocation management for PGA – part 4: Oracle 11.2.0.4 and AMM

This is the 4th post in a series of posts on PGA behaviour of Oracle. Earlier posts are: here (PGA limiting for Oracle 12), here (PGA limiting for Oracle 11.2) and the quiz on using PGA with AMM, into which this blogpost dives deeper.

As laid out in the quiz blogpost, I have a database with the following specifics:
-Oracle Linux x86_64 6u6.
-Oracle database 11.2.0.4 PSU 4
-Oracle database (single instance) with the following parameter set: memory_target=1G. No other memory related parameters set.

fritshoogland's picture

Oracle database operating system memory allocation management for PGA – part 3: Oracle 11.2.0.4 and AMM: Quiz

This is a series of blogposts on how the Oracle database makes use of PGA. Earlier posts can be found here (PGA limiting for Oracle 12) and here (PGA limiting for Oracle 11.2).

Today a little wednesday fun: a quiz.

What do you think will happen in the following situation (leave a response as comment please!):

-Oracle Linux x86_64 6u6.
-Oracle database 11.2.0.4 PSU 4
-Oracle database (single instance) with the following parameter set: memory_target=1G. No other memory related parameters set.

kevinclosson's picture

SLOB 2.2 Not Generating AWR reports? Testing Large User Counts With Think Time? Think Processes and SLOB_DEBUG.

I’ve gotten a lot of reports of folks branching out into SLOB 2.2 large user count testing with the SLOB 2.2 Think Time feature. I’m also getting reports that some of the same folks are not getting the resultant AWR reports one expects from a SLOB test.

If you are not getting your AWR reports there is the old issue I blogged about here (click here). That old issue was related to a Redhat bug.  However, if you have addressed that problem, and still are not getting your AWR reports from large user count testing, it might be something as simple as the processes initialization parameter. After all, most folks have been accustomed to generating massive amounts of physical I/O with SLOB at low session counts.

fritshoogland's picture

Oracle database operating system memory allocation management for PGA – part 2: Oracle 11.2

This is the second part of a series of blogpost on Oracle database PGA usage. See the first part here. The first part described SGA and PGA usage, their distinction (SGA being static, PGA being variable), the problem (no limitation for PGA allocations outside of sort, hash and bitmap memory), a resolution for Oracle 12 (PGA_AGGREGATE_LIMIT), and some specifics about that (it doesn’t look like a very hard limit).

But this leaves out Oracle version 11.2. In reality, the vast majority of the database that I deal with at the time of writing is at version 11.2, and my guess is that this is not just the databases I deal with, but a general tendency. This could change in the coming time with the desupport of Oracle 11.2, however I suspect the installed base of Oracle version 12 to increase gradually and smoothly instead of in a big bang.

kevinclosson's picture

SLOB Data Loading Case Studies – Part II. SLOB 2.2 For High-Bandwidth Data Loading.

This is Part II in a series. Part I can be found here (click here). Part I in the series covered a very simple case of SLOB data loading. This installment is aimed at how one can use SLOB as a platform test for a unique blend of concurrent, high-bandwidth data loading, index creation and CBO statistics gathering.

Put SLOB On The Box – Not In a Box

As a reminder, the latest SLOB kit is always available here: kevinclosson.net/slob .

Often I hear folks speak of what SLOB is useful for and the list is really short. The list is so short that a single acronym seems to cover it—IOPS, just IOPS and nothing else. SLOB is useful for so much more than just testing a platform for IOPS capability. I aim to make a few blog installments to make this point.

fritshoogland's picture

Oracle database operating system memory allocation management for PGA

This post is about memory management on the operating system level of an Oracle database. The first question that might pop in your head is: isn’t this a solved problem? The answer is: yes, if you use Oracle’s AMM (Automatic Memory Management) feature, which let’s you set a limit for the Oracle datababase’s two main memory area’s: SGA and PGA. But in my opinion any serious, real life, usage of an Oracle database on Linux will be (severely) constrained in performance because of the lack of huge pages with AMM, and I personally witnessed very strange behaviour and process deaths with the AMM feature and high demand for memory.

kevinclosson's picture

How Do I Know I Have The Latest SLOB Kit?

This is a quick blog post to show SLOB users how to determine whether they are using the latest SLOB kit. If you visit kevinclosson.net/slob you’ll see the webpage I captured in the following screenshot.

Once on the SLOB Resources page you can simply hover over the “SLOB 2.2 (Click here)” hyperlink and the bottom of your browser will show the full name of the tar archive. Alternatively you can use md5sum(1) on Linux (or md5 on Mac) to get the checksum of the tar archive you have and compare it to the md5sum I put on the web page (see the arrow).

 

latest-slob

Jonathan Lewis's picture

Parse Time

Here’s a little query I wrote some time ago to see where my time went while running a query. It’s nothing sophisticated, just one of those simple things you can do with v$active_session_history (or dba_hist_active_sess_history, if you don’t get to the crime scene in time).

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