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May 2016

Database Comparisons Using AWR Warehouse Part 1- ADDM Comparison

A lot of my ideas for blog posts come from questions emailed to me or asked via Twitter.  Today’s blog is no different, as I was asked by someone in the community what the best method of comparing databases using features within AWR when migrating from one host and OS to another.

RI Locks

RI = Referential Integrity: also known informally as parent/child integrity, and primary (or unique) key/foreign key checking.

I’m on a bit of a roll with things that I must have explained dozens or even hundreds of times in different environments without ever formally explaining them on my blog. Here’s a blog item I could have done with to response to  a question that came up on the OTN database forum over the weekend.

What happens in the following scenario:

PeopleSoft on Oracle 12c

I was asked by Dan Iverson from about my experiences of PeopleSoft on Oracle 12c.  I have seen a number of PeopleSoft Financials systems on 12c recently.  Generally, the experience is very positive, but one common feature is that they had all disabled Adaptive Query Optimization.

What is Adaptive Query Optimization?

How to find file and block# to dump in Exadata

Probably because of my past with Oracle Support, I find myself collecting traces and dumps on a regular basis. For example every time I see a row source operation that I would expect to perform only multiblock reads (e.g. Full Table Scan) doing single block ones I collect some block dumps to understand why that is happening. It’s just a matter of looking at the raw SQL trace file (or P1/P2 from ASH for that matter) for the unexpected single block reads, grab file# and block# and dump the block.

Single block reads in Exadata become “cell single block physical read” and the P1/P2 for the wait event don’t show the file#/block# but rather then cellhash# and diskhash# where the data came from. This is a little annoying to me because I can’t just grab cellhash#/diskhash# (plus bytes, that matches with the block size being a single block read) and dump that AS FAR AS I KNOW (corrections are very welcome here).

eAdam, SQLd360 hidden gem

The title is actually VERY wrong! eAdam isn’t a gem hidden inside SQLd360, it’s a standalone tool developed by Carlos Sierra and it’s been around for way longer than SQLd360. You can read more about eAdam here but in short its goal is to export AWR data in a portable way that can be restored in another database, something like a raw version of AWR Warehouse (kind of).

Every time you run SQLd360, the tool collects a reduced version of eAdam just for ASH data (both GV$ and DBA_HIST) for the SQL of interest, packs the result into the zip file and links it into the main page under column 5, “eAdam ASH”. The reason for doing so is SQLd360 has tons of reports built on top of the most important columns of ASH but what if you want to query another column that is not present in any report? With eAdam you basically have the whole ASH for this SQL ID to do all the data mining you want!

Graphing Exadata cells metrics with Telegraf, InfluxDB and Grafana


As a picture is worth a thousand words, we may want to visualise the Exadata cells metrics. What if you could do it the way you want? build your own graph? Let’s try to achieve this with 3 layers:

E-rows / A-rows

A recent post on the OTN database forum reminded me how easy it is to forget to keep repeating a piece of information after the first couple of hundred times you’ve explained it. No matter how “intuitively obvious” it is for one person, it’s new to someone else.

Here’s an execution plan that raised the question that prompted this note – it comes from calling dbms_xplan.display_cursor() with the ‘allstats last’ format option after enabling rowsource execution statisics (using hint gather_plan_statistics, or setting parameter statistics_level to all, or setting hidden parameter “_rowsource_execution_statistics” to true):

EM13c- Applying System Patches with the OMS Patcher

The OMS Patcher is a newer patching mechanism for the OMS specifically, (I know, the name kind of gave it away…)  Although there are a number of similarities to Oracle’s infamous OPatch, I’ve been spending a lot of time on OTN’s support forums and via email, assisting folks as they apply the first system patch to


The second edition of Cary Millsap‘s MASTERING ORACLE TRACE DATA (MOTD) is finally available. You can order it through I had the pleasure not only to review MOTD while Cary was working on it, but also to write a foreword that summarizes what I think about the book. So, if you are asking yourself whether you should buy MOTD, here is my opinion/foreword…

Blue Medora’s Brian Williams Blogs About Custom Monitoring Templates

Monitoring templates are an essential feature to a basic Enterprise Manager environment, ensuring consistent monitoring across groups and target types.  There’s an incredibly vast group of experts in the EM community and to demonstrate this, Brian Williams from Blue Medora, a valuable partner of Oracle’s in the Enter