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Updated: 15 hours 45 min ago

An UNDO in a PDB in Oracle 12c?

Thu, 2016-02-04 10:08


According to the Oracle 12cR1 documentation and concepts, it is 100% clear that there can be only one UNDO tablespace in a multitenant architecture and it is at CDB level; thus, a PDB cannot have any UNDO tablespace.

Are we really sure about that? Let’s test it!

First, we need a PDB with few tablespaces:


FRED_PDB> select NAME, OPEN_MODE, CON_ID from v$pdbs ;

-------------------------------------------------- ---------- ----------

FRED_PDB> select tablespace_name from dba_tablespaces ;


5 rows selected.

FRED_PDB> show parameter undo

------------------------------------ ----------- ------------------------------
temp_undo_enabled boolean FALSE
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS1


There we have an UNDO tablespace named UNDOTBS1 at CDB level and no UNDO at PDB level. Let’s try to create one :

FRED_CDB> create undo tablespace MY_PDB_UNDO ;

Tablespace created.



It worked! Is the Oracle documentation wrong? Let’s verify this weird successful UNDO tablespace creation:

FRED_PDB> select tablespace_name from dba_tablespaces where tablespace_name like '%UNDO%' ;

no rows selected

FRED_PDB> select tablespace_name from dba_tablespaces


5 rows selected.



No UNDO tablespace has in fact been created even if no error message has been raised by Oracle. Digging in the documentation, this is not a not a bug but a feature. Indeed, it is well specified that:

When the current container is a PDB, an attempt to create an undo tablespace fails without returning an error.


Please note that this is the behavior of the 12cR1 release; from my side, I think that this a “not yet feature” and we should see some real UNDO tablespaces in PDBs in the next release(s)!

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Categories: DBA Blogs

Expert Insights: Oracle NET Troubleshooting for DBAs

Thu, 2016-02-04 09:21


Troubleshooting connection issues with Oracle SQL*Net can be difficult at times due to the many options that can be taken during configuration. One of the options is where the file tnsnames.ora may be found. There are multiple locations available, and at times there is justification for having more than one copy of the file.

Perhaps there is a hybrid database naming configuration. Say there are a number of company-wide databases that are defined in Oracle OID, OpenLDAP or Active Directory, while local test databases are defined in one or more local tnsnames.ora files.

When one of the databases appears to no longer be available, even though you are quite sure it should be available, it’s good to know the default search order used by Oracle to resolve the name.

The Oracle names resolution default search order for Linux and Windows is explained here:



But wait, there’s more!

You may know that on linux and unix systems tnsnames.ora can be placed in the /etc directory.

Do you know just what happens when /etc/tnsnames.ora is used?  Learn that and more by watching the rest of the presentation.


Discover more about our expertise in Oracle.

Categories: DBA Blogs

RHEL vs OEL: Back in The Cold War?

Thu, 2016-02-04 07:32


I recently encountered a déjà vu on a client system, something I’ve seen repeatedly over the last couple of years. I’ve decided to write about it to prevent others from tumbling down the same rabbit hole.

Red Hat Enterprise Linux 6 system with a Red Hat support contract on it. A DBA had installed Oracle’s oracle-rdbms-server-12cR1-preinstall RPM package. The DBA was doing that based on Oracle support note “Linux OS Installation with Reduced Set of Packages for Running Oracle Database Server (Doc ID 728346.1)” which in the main section simply states:

“For Oracle database 12cR1 running on OL6/RHEL6,use command below to install all packages required for running Oracle software and resolve all dependencies.

yum install oracle-rdbms-server-12cR1-preinstall”

I’ve got a bit problem with how that note was written. Let’s take a look at what exactly happens to your RHEL 6 system, if you do that. First of all, you have to add Oracle’s yum repo to your yum configuration in order to be able to install that package. I’m a firm believer that you should never mix repositories of different Linux distributions on a production server, but I digress.

Then, when you actually install the RPM:

Resolving Dependencies
--> Running transaction check
---> Package oracle-rdbms-server-12cR1-preinstall.x86_64 0:1.0-14.el6 will be installed
--> Processing Dependency: kernel-uek for package: oracle-rdbms-server-12cR1-preinstall-1.0-14.el6.x86_64
--> Processing Dependency: libaio-devel for package: oracle-rdbms-server-12cR1-preinstall-1.0-14.el6.x86_64
--> Running transaction check
---> Package kernel-uek.x86_64 0:2.6.39-400.264.13.el6uek will be installed
--> Processing Dependency: kernel-uek-firmware = 2.6.39-400.264.13.el6uek for package: kernel-uek-2.6.39-400.264.13.el6uek.x86_64
---> Package libaio-devel.x86_64 0:0.3.107-10.el6 will be installed
--> Running transaction check
---> Package kernel-uek-firmware.noarch 0:2.6.39-400.264.13.el6uek will be installed
--> Finished Dependency Resolution

Some DBAs just skip over that section entirely and don’t pay attention to it, but right there Oracle has just installed their own kernel on a RHEL6 system. It’s also been activated and marked as default in grub.conf (which is the norm when installing a kernel RPM):

title Red Hat Enterprise Linux Server (2.6.32-400.37.15.el6uek.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.32-400.37.15.el6uek.x86_64 ro root=.....
initrd /initramfs-2.6.32-400.37.15.el6uek.x86_64.img

Let that sink in for a minute.

Leaving the system as it is, we’d be going ahead with the installation of the Oracle software, start running our database and go into production. If at any point in the future when we’re be rebooting our server, or if it crashes, we’d suddenly be running the UEK kernel and no longer the Red Hat kernel. There’s also a fairly ugly can of worms awaiting the DBA in question when the SA sees that someone has changed the default kernel.

But the real question is, what would running a different kernel do to us?

Well, Red Hat has an article that’s locked behind a subscriber-only wall. In a nutshell the message it contains is that third party packages are not supported by Red Hat, and third party kernels render all issues unsupported. Fair enough, that makes perfect sense, doesn’t it?

Thus, in essence, we’ve just voided support for our server. If we would hit any issue, we’d have to first clean out any Oracle packages that have replaced Red Hat’s – including the kernel – and reboot the machine back into a clean state, or we’d have to go to the maker of our custom kernel for support. That’s clearly not something you’d want to do during a critical issue on a production server.

If we read the aforementioned Oracle support note a bit more closely, way at the bottom in “Remarks”, as if it’s of no importance, we see this:

“RHEL systems registered with RHN or without an registration with an update channel and which should remain RedHat, can generate a primary list of missing dependencies (manually download the oracle-validated rpm package on public-yum):
# rpm -Uhv oracle-validated–.rpm”

“RHEL systems which should remain RedHat”.

Wait, what?

Doesn’t this basically mean that the note isn’t really telling us how to prepare for Oracle database software installation, but instead it’s telling us how to convert from RHEL to OEL? How to move our support contract over to Oracle?

Also note how the “Applies to” section in that particular note specifically does not include RHEL? It simply says “Linux”. This somehow reminds me of a certain horse that a certain city got as a present at some point in the distant past. Neatly packaged and easy to use, but potentially severe long term impact if you’re installing the package.

I’d like to appeal to both Oracle and Red Hat at this point, please folks, make this more clear. Both sides could do better here. There’s really no reason why solution 55413 should be locked behind a pay wall. It’s often the DBAs who are dealing with these packages to prep for a software install, and they often don’t have access to this content. On a similar note, support note 728346.1 also could be written in a much clearer manner to prevent this sort of confusion. Why is the kernel a dependency of that preinstall RPM? There’s absolutely no need for that.

We’re not in a cold war, are we?

TLDR; Don’t mix repositories of different distributions. Don’t install oracle-rdbms-server-12cR1-preinstall on RHEL unless you’re willing to deal with the consequences.

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Categories: DBA Blogs

Log Buffer #458: A Carnival of the Vanities for DBAs

Mon, 2016-02-01 10:38

This Log Buffer Edition covers various useful tips and tricks from blogs for Oracle, SQL Server and MySQL.


  • pstack(or thread stack) for Windows to diagnose Firefox high CPU usage
  • With the ever-changing browser landscape, we needed to make some tough decisions as to which browsers and versions are going to be deemed “supported” for Oracle Application Express.  There isn’t enough time and money to support all browsers and all versions, each with different bugs and varying levels of support of standards.
  • Are you effectively using Java SE 8 streams for data processing? Introduced in Java 8, streams allow you to process data in a declarative way and leverage multi-core architectures without writing multithreaded code.
  • If you are upgrading but would like to increase or decrease the number of data sources you must do so when installing the latest version.
  • When talking about BPM security, you need to know the about certain set of information and where those information will come from etc.

SQL Server:

  • Having fun with PARSENAME (SQL Spackle)
  • Time and Space: How to Monitor Drive Space in SQL Server
  • Application Security with Azure Key Vault
  • Declarative SQL: Using CHECK() & DEFAULT
  • Microsoft SQL Server 2016 Public Preview Boosts Database Security


  • Have you heard the news? As of MySQL 5.7.8, MySQL includes a new JavaScript Object Notation (JSON) data type that enables more efficient access to JSON-encoded data.
  • Oracle MySQL 5.7 Database Nears General Availability
  • Most of you know, that it is possible to synchronize MySQL and MariaDB servers using replication. But with the latest releases, it is also possible to use more than just two servers as a multi-master setup.
  • Transport Layer Security (TLS, also often referred to as SSL) is an important component of a secure MySQL deployment, but the complexities of properly generating the necessary key material and configuring the server dissuaded many users from completing this task.
  • Managing MySQL Replication for High Availability


Learn more about Pythian’s expertise in Oracle , SQL Server & MySQL.

Categories: DBA Blogs

Is the DBA Career Dead?

Thu, 2016-01-28 16:00


With the increased popularity of cloud services, one of the questions that I often receive is: “Is the DBA career dying? What will you do for a living in the future?” In this article I will give my personal opinion about the future of our beloved profession, and try to calm down those that have already started to look for another career.

The first thing that I want to point out is that when we started to work in IT we knew that it was a career that is different than most of the other ones out there. Its nature is  a dynamic and exciting one that reinvents itself all the time, with technological news showing up every single year and changing the entire landscape. We have chosen a field that pushes us to keep studying, learning and evolving, and this is the kind of mindset I want you to have while reading this article.

The Database Administrator role is not going anywhere. We are not an endangered species and won’t become one in the foreseeable future. Cloud is not our enemy. The data market is just evolving, and the cloud is bringing a lot of new things that will give us more power and more options.

In today’s market we have two very common problems:

  1. Companies can’t find enough people to fill in all positions.

We all know this one. I’m sure we all know several companies that have an open position for months, have interviewed dozens of people, and just can’t find anyone that suits the position.

  1. Companies want to keep their costs as low as possible.

Companies want to make money, and we had a big worldwide crisis just a few years ago that we are still recovering from. This means companies are trying to find ways to improve their productivity, while keeping their costs as low as possible.


In a scenario like this, the cloud offerings come as an aid to both improve our productivity as a DBA, and to help the company save money. Let’s think for a while about how many tasks we perform daily that don’t bring real value for the business. No doubt that when we’re planning the new high availability solution, or doing performance tuning on that slow query we can see the value that it will bring to the company. In the first case, this will guarantee that all applications are up and running at full speed when the company needs it. The latter will make sure that the server is handling the workload, running more sessions at the same time, and making both internal and external customers happy.

But how about the time you spent trying to find more disk space for all your databases? How about trying to find disk space for all your backups because the database has grown too large and we didn’t plan ahead? Then there’s all the time that you spend installing SQL and Windows patches. I know, in some big companies, we have a dedicated SAN admin and the infrastructure administrators that will worry about those tasks, but that’s not the everyone’s reality. The vast majority of small and medium companies have a small team that is responsible for multiple areas. Why? Scroll up and read problems 1 and 2 om my list above one more time.

I’ll wait for you.

Now, let’s imagine another reality. Let’s imagine a world where I receive a disk space alert for my backups. The company has acquired a new company, the database growth was much bigger than expected, and we ran out of disk space. I go to a web portal and a few mouse clicks later I have 1TB of disk available to me. All I have to do is open SQL Server Management Studio and change my backup jobs to use the new storage area. Problem solved in less than 15 minutes.

Let’s envision a world where I can get all those small databases I have that are not too important for the business (yeah, we all have a lot of those, don’t lie to yourself) and move those databases to the cloud so they don’t use our precious server resources. I don’t need to worry about patching and managing those databases. Wouldn’t that be great? And how about getting rid of the QA and testing servers and replacing them with virtual machines that can just turn off when they are not in use and save money? And those huge tables with hundreds of millions of rows that causes us problems every single day. Wouldn’t it be great if I could replace that complicated sliding window partition solution that we developed to manage historic data, and instead make SQL Server automatically move old and unused data to the cloud, while also keeping the data available for end users in a transparent way?

Cloud is indeed a career shift dynamic, but not one that will kill the database administrator role and destroy families. Instead, it’s one that will make us more efficient, provide us with tools and options to focus ourselves on tasks that bring value to the company. It’s a solution where we can use the existing hardware more efficiently and make our lives easier. Embrace the changes just like we embraced all new technologies that came before it, and use each one as a tool to be successful in your role.


Discover more about our expertise in the Cloud.

Categories: DBA Blogs

My Virtual Internship with Pythian

Thu, 2016-01-28 14:38

My internship with Pythian started in October and has been an incredible opportunity to build upon my project management skills with a virtual internship. I never imagined working for a tech company. As business students, we are often characterized as lacking the hard skills needed for industries as competitive as those in STEM fields. After my internship with Pythian, I know that my perspective can bring value to a team especially within the tech industry. My work with Pythian has inspired me to apply to computer science programs in Taiwan after I graduate in June.

During my time at Pythian I worked on the Pythia Program which is Pythian’s commitment to improving gender diversity by encouraging, promoting and retaining women and young girls in STEM fields. I was able to work with managers across many different departments and learn how to be part of a virtual team, while building a plan for the Pythia Program.


Making an impact for women in STEM fields

The Pythia program is setting an incredible precedent for other tech companies in North America and I am very excited that I was a part of that process. Researching and compiling data on women in STEM fields, particularly the tech industries, was an eye-opening experience. Identifying the pain points for underrepresented groups in tech, particularly women, is key in developing solutions that encourage women to seek positions in this field.

I am looking forward to seeing Pythian’s impact in the local community with Technovation and the impact on the young women who will be walking the halls and learning from such great mentors. Pythian is not only making great strides for the young women in their local community, but for all women in tech by setting an example with their own diversity initiatives.


Working with the women of Pythian

While assigned to the Pythia Program, I was lucky to be working with women who were heads of their departments and brought a diverse range of skills to the table. Whether building communication plans with the marketing department, or measuring progress with the organizational development team, I was always challenged to look at the issue from different perspectives.

As a project manager it can be very easy to stay on the periphery and remain an outsider, and admittedly this was a concern of mine as an intern and a newcomer to Pythian. The level of trust that the OD department put in me, and their guiding hand in helping me navigate through the on boarding period was instrumental to our success.

Working with women from many different technical backgrounds, I was able to learn much more than if I had stayed within one specific department. I cannot say how important it is as a young women to work with other women on the Pythia Program. It was inspiring to be able to work with accomplished women with so much expertise that they were willing to share.


Working virtually is a whole different ballgame

It has been said that virtual work can be trying and difficult for those new to the team, however my time with Pythian was the complete opposite. I am very thankful to have been able to navigate a virtual internship with such incredible support from the OD team. The lines of communication have always been open, and this has been instrumental to our success on the Pythia Program.

Pythian’s managers made themselves accessible and available during my time on the Pythia program, and their guidance was excellent, as was learning from their experiences.

All in all, I could not have asked for a greater internship than my time at Pythian. I was able to work on a project that was important to me as a woman, while working with other women at Pythian. Together we made an impact within the organization and in the local tech community in Ottawa. In the months to come we will see the reach of the Pythia Program on others. For myself, the experience has been impressive as I apply to computer science programs abroad and see my own future in tech. I look forward to following the continued success of Pythian and the Pythia Program.


Find out more about the Pythia Program.

Categories: DBA Blogs

SQL Server Cumulative Update changes

Wed, 2016-01-27 12:42


Microsoft recently released the first Cumulative Update for SQL Server 2012 SP3 This CU addresses 8 issues in the product. But more importantly, it also marks a big shift in the Cumulative Update message sent by Microsoft.

For a long time, there was a discussion between DBAs about when/if we should apply a cumulative update. The Microsoft official message always have been that we should apply a cumulative update only if we were facing an issue in our environment caused by a know and fixed bug. This was also evident by the fact that to be able to download a cumulative update it was necessary to register on their website, provide an email address and they would send a link to download the package to your email address.

So, what has changed? Starting now, the latest cumulative update package will be maintained in the Download Center instead of the hotfix server. This will eliminate the need to register to get the latest package, but this is not the only thing that has changed, the entire message that you can read in the knowledge base article has changed, and instead of a warning message saying that we should not install the package unless it was necessary, now we have:
“ Microsoft recommends ongoing, proactive installation of SQL Server CUs as they become available:
SQL Server CUs are certified to the same levels as Service Packs, and should be installed with the same level of confidence
Historical data show a significant number of support cases involve an issue that has already been addressed in a released CU
CUs may contain added value over and above hotfixes such as supportability, manageability, and reliability updates
As with SQL Server Service packs, Microsoft recommends that you test CUs before deploying to production environments”

This is a big change from what we had before. The concerns we had in the past were necessary because the hotfixes were not tested in the same levels as the service packs were. There were no regression tests and not all possible integration tests were executed. So there was a real concern that something could go wrong in specific scenarios that were not tested. But this has changed and now every cumulative update goes through all the same certification levels that are applied to Service Packs.

This is a trend that is happening not only with SQL Server, this is the result of an agile development effort that is happening throughout the entire Microsoft stack of products. Windows, both personal and server editions already have constant updates instead of Service Packs for some time now and it seems SQL Server will soon follow this road.

This big change in how Microsoft deliver updates bring us to an interesting discussion: how to manage frequent and constant product updates in your environment? The last item in the Microsoft message clearly says that you need to test CUs, just like you test Service Packs before applying. Are customers willing to go through testing and patching processes every couple of months when a new CU is released? How can we convince customers of the benefit of having the latest version of the product?

I believe people will eventually get used to this new model of constant updates and catch up, creating plans to update more often their environments, maybe not apply every single CU, but apply them every 2 releases, or every half year, etc.

What do you think? How do you see this new model fitting in your existing environment? I would love to know other people experience on this subject.

Oh, and before I forget: you can download the latest CU for SQL 2012 SP3 that I mentioned in the beginning of the article. The link will not change for every release, so you will always be able to download the latest version using this link.

Categories: DBA Blogs

How do you define IT innovation?

Wed, 2016-01-27 10:57

Find out how the experts answered at Pythian’s Velocity of Innovation event in San Francisco

Once again, I had the pleasure of moderating another Velocity of Innovation event this past November in San Francisco. Both panelists and guests brought with them a varied range of insights, experiences and perspectives. And as always, this resulted in a thoughtful and lively discussion.

The format of these events is to put three IT leaders with expertise in a particular area in a room, and start a conversation. With our Velocity events, we always start our discussions with a few questions, and the panelists provide some answers. But the idea is to get a conversation going between the audience and panelists.

That day, we discussed a range of subjects from IT innovation, to security, to our favourite wrap-up topic: taking a look into the IT crystal ball and commenting on what current technology trends will really take hold in the future. This last one is always a lot of fun. In this blog post I will provide just some of the highlights from the first discussion topic at the event: innovation and agility in IT.

On our panel were three IT experts:

Sean Rich is the director of IT at Mozilla, leading their application services group. He takes care of web operations, along with pretty much everything data related.

Cory Isaacson is the CTO at Risk Management Solutions. He’s currently bringing big data and scalable systems together to create a new cloud-based platform.

Aaron Lee is Pythian’s VP of transformation services. He runs a team that specializes in helping clients harness technology to deliver real outcomes. Usually they involve things like big data, DevOps, cloud, advanced analytics. He’s involved in some of the most leading edge initiatives for Pythian customers.

I started the discussion by asking the panel, and the audience members, to discuss the notions of innovation and agility, and to try to describe what they have explicitly done to improve innovation and to make their own organizations and those of their customers more agile.

Cory: My business evaluates risk. Our customers are the biggest insurance companies in the world. We run catastrophe models for them so that we can actually see what an earthquake might cost them or a hurricane, for example. I run technology for the company and have to build all the software. We’re innovating tremendously and so now it’s funny because our executives ask us to evaluate the risk of our own projects. We’re trying to do some very, very innovative things. I don’t know if any of you have an insurance background, but it’s not the most up-to-date industry when it comes to technology. As you know it’s been around a long, long time. But at my company some of the things that we’re trying to do are, honestly, more advanced than most other things I’ve ever seen in my career. And that’s why I took the position. But when you’re doing innovation, it is risky. There’s no way around it. There are a lot to evaluate: from different algorithms to the risk models and the catastrophe models. How do you evaluate them? Can you actually run them? We’re going from a 25-year-old desktop application, running on Microsoft SQL server to a cloud-based implementation. We’re taking thousands of servers and trying to move all the customers into a cloud implementation.

Sean: In my role I’m interpreting it a little bit differently. Innovation is doing something new. In an effort toward agility, one of the things that we’re doing within our organization is enabling the agility of our business partners, by changing our own operating model. Traditional IT where we run all the services and infrastructure necessary to drive the business, actually taking more of an enabler or a partnership approach where we’re doing things like encouraging shadow IT, encouraging the use of SaaS applications and helping them really do that better through different service offerings like vendor management or change management when it comes to user adoption of certain platforms, data integration so that when we have work flows that span multiple areas of the business, we can complete those without moving data around manually and some of the other problems that come with that. That’s one way that we’re doing new things, looking at ourselves differently, what new capabilities do we need to develop, processes, tools and skills to enable agility for our marketing group or our product lines, as an example. That’s a little bit of one way I think about it.

Then I asked: What gets in the way of agility?

Aaron: I think it’s interesting considering we used to improve innovation by looking right at the root of the motivation for it. Why are we going down this path, trying to innovate something and what is the value of that thing we’re trying to innovate? It’s my belief that the thing that we should value in our colleagues is their judgment. The pre-conditions for being able to offer judgment are you need to be fully informed, you need to be aligned with an objective, there needs to be a reason and even an incentive to offer that kind of input. If the shared goals around innovation opportunities aren’t defined in a way that actually lead to success over time, then the business is just like any other organism: it gets its fingers burned, it starts to get more risk adverse and then it becomes harder and harder to execute any kind of change agenda. Planning in a way that is likely to have a good long-term outcome, even at the outset of any sort of initiative, is one key success criteria that we put in place to help ourselves and our customers get to a good place.

Attendee 1: Established companies who have the ability to have long-term leaders are losing the race because they’re not agile. Those leaders need to transform in their mind first to say, “This is something that needs to be done,” and commit to it and take maintain an attitude where, having given that direction, don’t penalize employees for failure as they run small experiments. A lot of companies have, complex projects where they spin-off a small team, say, “You go do whatever you want and we are going to give you some limited funding, but we are not going to ask you for results.” CEOs and COOs are looking for, “If I spend 10 million bucks, what am I going to get for it?” When you focus on bottom line results, then you hide the cost of innovation.

Sean: Yeah, it’s culturally endemic, sort of near-term focus on success instead of on the long term and the impact that has on innovation.

Cory: There are some companies, like Google who have been known to allow an engineer to take a day a week or a day every two weeks and just look at things. I think though, the challenge is you have to get your organization up to the point where this is an economically viable thing to do. That’d be something I’d love to do with our team, but they’re so stressed out on getting the next thing done. Once we get more ahead of the curve, I think we could do that kind of thing.

The discussion went on to cover operationalizing innovation, or making it a program within an organization, before we moved on to other similarly thought-provoking subjects.

Interested in being a part of a discussion like this one? VELOCITY OF INNOVATION is a series of thought-leadership events for senior IT management hosted by Pythian. Pythian invites leading IT innovators to participate in discussions about today’s disruptive technologies: big data, cloud, advanced analytics, DevOps, and more. These events are by invitation only.

If you are interested in attending an upcoming Velocity of Innovation event in a city near you, please contact

Categories: DBA Blogs

Hybrid Databases: Key to Your Success

Mon, 2016-01-25 14:51

Almost every company’s success is contingent upon its ability to effectively turn data into knowledge. Data, combined with the power of analytics, brings new, previously unavailable business insights that help companies truly transform the way they do business—allowing them to make more informed decisions, improve customer engagement, and predict trends.

Companies can only achieve these insights if they have a holistic view of their data. Unfortunately, most companies have hybrid data—different types of data, living in different systems that don’t talk to each other. What companies need is a way to consolidate the data they currently have while allowing for the integration of new data.

The Hybrid Data Challenge

There are two primary reasons why data starts life in separate systems. The first is team segregation. Each team in an organization builds its systems independently of one another based on its unique objectives and data requirements. This, in part, is also the second reason. Teams often choose a database system that specializes in handling the specific application tasks. Sometimes they need to prioritize for scalability and performance. Other times, flexibility and reliability are more important.

Businesses need to evolve their data strategy to establish and create a “data singularity,” which summarizes the total of their information assets as a competitive, strategic advantage and enables real-time knowledge. A key objective of this strategy should be to reduce data movement, especially during processing and while executing queries, because both are very expensive operations. As well, data movement, or data replication in general, is a very fragile operation, often requiring significant support resources to run smoothly.

Enter The World Of Hybrid Databases

A hybrid database is a flexible, high-performing data store that can store and access multiple, different data types, including unstructured (pictures, videos, free text) and semi-structured data (XML, JSON). It can locate individual records quickly, handle both analytical and transactional workloads simultaneously, and perform analytical queries at scale. Analytical queries can be quite resource-intensive so a hybrid database needs to be able to scale out and scale linearly. It must also be highly available and include remote replication capabilities to ensure the data is always accessible.

In the past, many organizations consolidated their data in a data warehouse. Data warehouses gave us the ability to access all of our data, and while these systems were highly optimized for analytical long-running queries, they were strictly batch-oriented with weekly or nightly loads. Today, we demand results in real time and query times in milliseconds.

When Cassandra and Hadoop first entered the market, in 2008 and 2011, respectively, they addressed the scalability limitations of traditional relational database systems and data warehouses, but they had restricted functionality. Hadoop offered infinite linear scalability for storing data, but no support for SQL or any kind of defined data structure. Cassandra, a popular NoSQL option, supported semi-structured, distributed document formats, but couldn’t do analytics. They both required significant integration efforts to get the results organizations were looking for.

In 2008, Oracle introduced the first “mixed use” database appliance—Exadata. Oracle Exadata brought a very high performant reference hardware configuration, an engineered system, as well as unique features in query performance and data compression, on top of an already excellent transactional processing system, with full SQL support, document-style datatypes, spatial and graph extensions, and many other features.

In recent years, vendors have started more aggressively pursuing the hybrid market and existing products have started emerging that cross boundaries. We can now run Hadoop-style MapReduce jobs on Cassandra data, and SQL on Hadoop via Impala. Microsoft SQL Server introduced Columnar Format storage for analytical data sets, and In-Memory OLTP—a high performance transactional system, with log-based disk storage. Oracle also introduced improvements to their product line, with Oracle In-Memory, a data warehouse with a specific high-performance memory store, bringing extreme analytical performance.

Choosing A Hybrid Database Solution

Rearchitecting your data infrastructure and choosing the right platform can be complicated—and expensive. To make informed decisions, start with your end goals in mind, know what types of data you have, and ensure you have a scalable solution to meet your growing and changing organizational and business needs—all while maintaining security, accessibility, flexibility, and interoperability with your existing infrastructure. A key design principle is to reduce your data movement and keep your architecture simple. For example, a solution that relies on data being in Hadoop but performs analytics in another database engine is not optimal because large amounts of data must be copied between the two systems during query execution—a very inefficient and compute-intensive process.

Have questions? Contact Pythian. We can help analyze your business data requirements, recommend solutions, and create a roadmap for your data strategy, leveraging either hybrid or special purpose databases.

Categories: DBA Blogs

SQL On The Edge #7 – Azure Data Factory

Thu, 2016-01-21 08:46

As the amount of data generated around us continues to grow exponentially, organizations have to keep coming up with the solutions of our new technological landscape. Data integration has been part of this challenge for many years now and there are many tools that have been developed specifically for these needs. Some tools are geared specifically from moving data from point A to point B, other tools provide a full ETL (Extract-Transform-Load) solution that can work with many products using all kinds of different drivers.

For many years, the first party tool of choice for SQL Server professionals has been SSIS. Interestingly, even though it’s called SQL Server Integration Services, SSIS is really a general purpose ETL tool. If you want to extract data from Oracle, transform it with the full expressive capabilities of .NET and then upload it to a partner’s FTP as a flat file, you can do it in SSIS!

As we continue our journey into the cloud and hybrid environments, more tools will start coming up that will work as an ETL PaaS offering. You won’t have to manage the pipeline’s OS, hardware or underlying software, you’ll just create your data pipelines and be off to the races.

What is it?
Azure Data Factory (ADF) is Microsoft’s cloud offering for data integration and processing as a service. You don’t have to install any bits or manage any software, you’re only responsible of creating the pipelines. Since it’s developed to run inside the Azure the tool also has some pre-made hooks that make it really easy to interoperate with other Azure services such as blob storage, HDInsight or Azure Machine Learning.

On premises you would need a machine (VM or physical), you would need a license for your ETL tool (let’s say SSIS), then you would need to keep SSIS patched up, the machine up to date, think about software and hardware refreshes and so on. Using ADF, you can focus on the pipeline itself and not have to worry about what underlying sofware and hardware is actually making it work. The service supports a wide array of sources and targets (and continues to grow) and also robust options for scheduling the pipeline or running continuously to look for new slices of data.

When should you use it?
If you’re thinking about creating a new SSIS package and find that your sources are all web or cloud based then ADF is a good choice. Build a prototype of your pipeline, make sure that it supports your expected transformations and then you can operationalize it on the cloud. As a PaaS offering, it takes away the time, cost and effort of having to deal with the underlying bits and you can just focus on delivering quality data pipelines in a shorter timeframe.

Service Limitations

Like all new things in Azure, there are still some service limitations. The biggest one at the moment is that the service is only available in the West US and North Europe regions. If you don’t have resources in those regions and will be moving a lot of data then I would advise to start learning the service and prototyping but not put in production the pipelines. The reason for that is that any data movement from outside the region will have an outbound transfer cost. If your resources are in those regions then there’s no charge and you can ignore this warning.

In the Demo video we’ll look at the user interface of Azure Data Factory, how to add a source and target, scheduling and checking the status of the pipeline. Enjoy!

Discover more about our expertise with SQL Server in the Cloud.

Categories: DBA Blogs

How to Migrate from On-Premises to Azure SQL Database

Fri, 2016-01-15 15:14

The Azure SQL Database is improving its capabilities day-by-day. The “Cloud-first” strategy used by Microsoft is also an incentive to start using the Azure’s SQL Database as a Service (DaaS) offer.

In this article I’ll explain all the steps to move your database from on-premises to Azure, using three different approaches. You will need to choose the right one based on your migration strategy and on the database that you are migrating. Don’t forget that not all the features supported on-premises are supported on Azure, so some additional work may be needed prior to the migration.

I’ll show how to migrate a database to Azure SQL Database by using two general methods:

  • Using the SQL Server Management Studio – Recommended when there are no code compatibility issues blocking the cloud migration.
  • Using the SQL Server Data Tools – This approach is highly recommended when there are migration barriers, as the process of detecting and fixing the issues is simpler and more direct.

If you are in doubt about which one to use, the recommendation is to start by using the SQL Server Management Studio approach and, in case of failures, proceed with the SQL Server Data Tools.

Migrate Using SQL Server Management Studio

SQL Server Management Studio (SSMS) offers two direct ways to transfer a database to an Azure SQL Database. To proceed, connect to the SQL Server instance and run either the “SQL Database Deployment Wizard” or the “Export data-tier application” option from SQL Server Management Studio.


If you cannot find the preferred option, you will need to update your SQL Server Management Studio (SSMS), which is now a free standalone product. You can do this by downloading the latest version.

The primary difference between the two options is that the “Deploy“ option requires an existing Database server in Azure and will directly deploy the on-premises database to that location.  The difference is that afterwards the “Export” option will create a file to be imported from the Azure portal. The exported file can be loaded straight to an Azure Blob Storage account, which will help avoid an extra step to copy the file (recommended).

NOTE: For both options, an Azure Blob Storage account with a container and an Azure SQL server are needed.

Migration Steps Using the Deployment Wizard
  1. Right-click the database and select the Deploy Database to Microsoft Azure SQL Databaseimg2
  2. Fill in the required fields.
    The server information is for the target (Azure SQL Database server). The settings to define the price tier are also configured at this stage. The bacpac file will be created locally and then applied on the Azure SQL Server, and because of this, we will need to store the bacpac file in a temporary place in the server.
  3. Click Next.


  1. Review the settings and click Finish.img4
  2. Wait for the process to complete.
    At this stage the wizard will validate the database, create the DACPAC file, and apply the Azure SQL Server to create the database.


  1. The database is now ready to use the server admin account to access the Azure SQL Server.


Migration Steps using the Export Data-Tier Application Process
  1. Right-click the database and select the Export Data-tier Application.011316_1528_HOWDOYOUMIG6.png
  2. Save the file in an Azure Blob Storage Account. You will need the account name and access key.
  3. Select the container and click Next.011316_1528_HOWDOYOUMIG7.png
  4. Click Finish, and wait for the processing to complete.
  5. Once the process completes a “Success” message is seen as shown in the screen below. Otherwise, there are items needing to be resolved to make the database capable of being converted into an Azure SQL Database.011316_1528_HOWDOYOUMIG8.png
  6. Connect to the Azure portal and choose the SQL Servers.
  7. Select the SQL Server location where the database should be created, and then click the Import Database icon as shown below.011316_1528_HOWDOYOUMIG9.png
  8. Complete the required settings, including the BACPAC file location, price tier, and server administrator’s password, and then click Create.011316_1528_HOWDOYOUMIG10.png
  9. Once the process completes, the database will be seen in the list.


Migrate Using SQL Server Data Tools

By using the SSMS to migrate the database using a DACPAC, we don’t have the needed flexibility to properly detect and fix the found issues. For this purpose, the SQL Server Data Tools – Business Intelligence is a better option to analyze the database objects. To proceed with this option, follow the steps below.


Creating the Main Project
  1. Using the SQL Server Data Tools BI, click the SQL Server Object Explorer tab and connect to the on-premises instance:


  1. Right-click the database to be migrated to Azure, and then click Create New Project.
  2. Add a name to the project and select a path to save the project files.
  3. Click next and wait for the processing to complete.


  1. After the project is created, right-click the project root, go to properties and change the Target Platform to Azure SQL Database. Save and close.


  1. Right-click the project and click Rebuild. If problems are detected, all the errors will be shown in the Error List.


  1. Go to File->New->Project, give a project name (I will name it AWAzure) and in the Solution option, click Add to solution:




Creating the New Schema

In order to filter the non-supported features and find the code to be corrected, the next step is a Schema Comparison creation. Follow the steps shown:


  1. Now, select the options. Click the icon shown.


  1. In the Schema Compare Options window, click to clear the following known non-supported items:
  • Aggregates
  • Application Roles
  • Assemblies
  • Asymmetric Keys
  • Broker Providers
  • Certificates
  • Contracts
  • Defaults
  • Extended Properties
  • Filegroups
  • FIleTables
  • Full-Text Stoplists
  • Full-Text Catalogs
  • Full-Text Indexes
  • Message Types
  • Partition Functions
  • Partition Schemes
  • Queues
  • Remote Service Bindings
  • Rules
  • Sequences
  • Services
  • Symmetric Keys
  • Used-Defined Types (CLR)
  • XML Indexes
  • XML Schemas Collections
  1. Click Ok and save the Schema Comparison, as it can be useful later.
  2. Select the source: The On-premises database.


  1. Select the Target: The empty SQL Server create project.


We will have the following:


  1. Now, click Compare. Wait for the process to complete and then click Update (click YES in the confirmation pop-up), to update the selected target.
  1. Next, go to the AWAzure (the target) project, right-click on the root, go to properties, and change the Target Platform to Azure SQL Database.
  1. Click Save and Close the screen.


Resolving Problems

Now it’s time to resolve the problems. Check the errors tab and double click on each found item to open the code. Resolve the issue and save the file.


Use the filter to ensure you are dealing with the right project.




Deploying the Schema

After the schema revision, we can publish the database.

  1. To publish the database, right click the AWAzure project, and click Publish.
  1. Edit the target instance and connect to the Azure SQL Server:


  1. Fill in the database name and click Publish.


Moving the Data

The schema is deployed. Now it is time to move the data. To do this, use the Import and Export Wizard, from the SQL Server Management Studio.

  1. Connect to the on-premises instance, right click the database used as the data source and follow the steps shown:


  1. In the wizard, confirm the Server name and the source database, and then click Next. 


Now, do the same for the Azure SQL Database.

  1. In the Destination field, select SQL Server Native Client 11.0, fill in the server name, and select the target database.img9
  2. Click Next.
  3. For this step, keep the first option selected, and then click Next.img10

Select all the tables and views from the source. Notice that SQL Server will automatically map the target tables on Azure.

About data hierarchy: If foreign key constraints are being used in the database, the data migration should be made in phases to avoid failure. This needs to be analyzed prior to the final migration.


  1. Make sure that all the tables are highlighted and click Edit Mappings.
  2. Select Enable Identity Insert and then click Ok.
  3. Then, in the main Wizard window click Next.


  1. Make sure the Run immediately check box is selected and click Next.


  1. In the following screen, review the options, and then click Finish.


  1. Monitor and the data transfer and close the wizard.



That’s it. I hope that the steps were clear and this article was useful. If you have questions, do not hesitate in post your comment or contact me using twitter (@murilocmiranda). “See” you in another article.


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Categories: DBA Blogs

Issues with Oracle Secure External Password Stores

Fri, 2016-01-15 15:09

In the previous article, I covered the basics of how to remove database passwords (credentials) from Oracle monitoring or backup scripts and how to instead secure them using a “Secure External Password Store” (SEPS) and Oracle Wallet.

While this mechanism is far better than putting a plain text credential in a script file, one of the more advanced options, specifically tying the files to the local host with the “-auto_login_local” introduces bugs with Oracle 12cR1 software not present with other versions.

This article goes deeper into how to harden the approach, lock-down script access to the local server, and workaround Oracle Wallet limitations and bugs.


Issues with the “-auto_login_local” Option

Oracle suggests using the “-auto_login_local” option to secure an Oracle Wallet and only allow it to be used on the server on which it was created and by the user that created it. See MOS document: “How To Prevent The Secure Password Store Wallet From Being Moved to Another Host (Doc ID 1114599.1)

This is supposed to protect from a bad actor obtaining a copy of the file, say from a backup, and being able to use it (and the credentials contained within it) from another machine. Unfortunately, there’s a number of issues and problems with this option:

    1. There are ways to work around the protection it provides.
    2. The option fundamentally doesn’t work with (while it does with and This is clearly an Oracle bug.


By-passing the “-auto_login_local” Parameter”

The “-auto_login_local” parameter is supposed to protect the Wallet from being used on another server. However testing proves that this is really easy to workaround.

The basics of SEPS and Oracle Wallets I covered in my previous article. To enable the -auto_login_local option, we simply modify the existing Wallet file using the orapki utility:

$ orapki wallet create -wallet "/u01/app/oracle/wallet" -auto_login_local
Oracle PKI Tool : Version - Production
Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:

$ mkstore -wrl "/u01/app/oracle/wallet" -listCredential
Oracle Secret Store Tool : Version - Production
Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:
List credential (index: connect_string username)
1: ORCL scott



Testing on the local machine shows that the connection using the Wallet works as expected:

$ sqlplus /@ORCL

SQL*Plus: Release Production on Wed Jan 13 15:27:54 2016

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

  2         SYS_CONTEXT('userenv','DB_NAME') DB_NAME,
  4  from dual;

--------------- ------------ ------------   ORCL         SCOTT



It’s not overly simple for a bad actor already inside the network to obtain all of the information they’d need to access the database remotely, but it is possible. Say, for the sake of an example, that a bad actor obtained access to a backup of the OS. From that they could see the DBA scripts and how they connect, obtain the network files such as the sqlnet.ora and tnsnames.ora files, and obtain the Oracle Wallet files.

If a SEPS and Oracle Wallet was not being used, they’d presumably also be able to work out the database credentials as they’d either be hard-coded in the DBA script files or obfuscated in some other plain text file (not hard to reverse engineer).

Copying the cwallet.sso and ewallet.p12 (and maybe the tnsnames.ora) files to a secondary server simulates the actions of the “bad actor”.

But trying to make the same connection from the secondary server (which the “bad actor” controls) shows the “ORA-12578: TNS:wallet open failed” error:

$ sqlplus /@ORCL

SQL*Plus: Release Production on Wed Jan 13 15:38:50 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

ORA-12578: TNS:wallet open failed

Enter user-name:


This is the expected error when the “-auto_login_local” option is used. However it’s simple to work-around.

MOS Note 1114599.1 suggests that the /etc/hosts file may cause this error. So the first thing to try is changing the name in the hosts file to that of the legitimate DB server:

# cp /etc/hosts /etc/hosts.backup
# cat /etc/hosts.backup | sed -e "s/HACKED_OS/DBSERVER/ig" > /etc/hosts
# su - oracle -c "sqlplus /@ORCL"

SQL*Plus: Release Production on Wed Jan 13 15:59:53 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

ORA-12578: TNS:wallet open failed

Enter user-name:


Clearly that didn’t help the situation at all. Undoing that and instead trying to rename the compromised server (separately as root) gives a different error:

# cp /etc/hosts.backup /etc/hosts
# hostname

# hostname DBSERVER
# hostname

# su - oracle -c "sqlplus /@ORCL"

SQL*Plus: Release Production on Wed Jan 13 15:53:02 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

ORA-21561: OID generation failed

Enter user-name:


But if we do both:

# cp /etc/hosts /etc/hosts.backup
# cat /etc/hosts.backup | sed -e "s/HACKED_OS/DBSERVER/ig" > /etc/hosts
# hostname DBSERVER
# su - oracle -c "sqlplus /@ORCL"

SQL*Plus: Release Production on Wed Jan 13 16:05:53 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Last Successful login time: Wed Jan 13 2016 16:04:45 -07:00

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

  2         SYS_CONTEXT('userenv','DB_NAME') DB_NAME,
  4  from dual;

--------------- ------------ ------------   ORCL         SCOTT



So if we change both the hostname via the hostname command (or in the /etc/sysconfig/network file) and update the /etc/hosts file, then the -auto_login_local security is by-passed and we can log into the database from a compromised machine using the credentials stored in the Oracle Wallet!

Important to note there that I’m connecting to a database but using a Wallet file that was created using the software.


ORA-12578 with Oracle Database

To make matters worse, with Oracle the -auto_login_local option doesn’t even work at all.

Back on the database server (legitimate DBA activity – not simulating a “bad actor”), creating the Oracle Wallet file using software seems to prevent connectivity locally:

$ orapki wallet create -wallet "/u01/app/oracle/wallet" -auto_login_local
Oracle PKI Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:

$ sqlplus /@ORCL

SQL*Plus: Release Production on Wed Jan 13 16:21:05 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

ORA-12578: TNS:wallet open failed


This is unexpected behaviour and clearly shows and Oracle bug. Taking off the -auto_login_local option (by using -auto_login) shows that the Oracle Wallet does indeed work on this server:

$ orapki wallet create -wallet "/u01/app/oracle/wallet" -auto_login
Oracle PKI Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:

$ sqlplus /@ORCL

SQL*Plus: Release Production on Wed Jan 13 16:22:30 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Last Successful login time: Wed Jan 13 2016 16:20:38 -07:00

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

  2         SYS_CONTEXT('userenv','DB_NAME') DB_NAME,
  4  from dual;

--------------- ------------ ------------   ORCL         SCOTT



Hence, there clearly is a bug that’s specific to the software where as the ORA-12578 error is returned when it shouldn’t be. Repeating the same procedure using or software does not exhibit the same error.

And it’s important to understand that it doesn’t matter which version of the database the connection is to. The problem is specific only to which software was used to create the Wallet file. So creating the Wallet with software just to use against a database works without issue.


Harding Using Other Strategies

Due to the above mentioned issues, other strategies can be used to harden the connections and credential management for use by DBA scripts.


Using localhost or

The simplest way to prevent the Wallet files from being usable on another server is to change the OracleNET Service Name to an EZconnect string that uses localhost or For example, on the DB server:

$ mkstore -wrl "/u01/app/oracle/wallet" -create -createCredential localhost:1521/ORCL scott
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Enter password:
Enter password again:
Your secret/Password is missing in the command line
Enter your secret/Password:
Re-enter your secret/Password:
Create credential

$ sqlplus /@localhost:1521/ORCL

SQL*Plus: Release Production on Wed Jan 13 16:33:27 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Last Successful login time: Wed Jan 13 2016 16:31:50 -07:00

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> show user


Now if we try using the Oracle Wallet files on a compromised server (with the /etc/hosts and /etc/sysconfig/network spoofing as described previously), the connection attempt routes through the localhost back to the compromised server and not to the database server. Hence a connection attempt gives:

[oracle@HACKED_OS ~]$ sqlplus /@localhost:1521/ORCL

SQL*Plus: Release Production on Wed Jan 13 16:34:27 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

ORA-12541: TNS:no listener


Thus, by using an EZconnect connection string and localhost instead of the actual server’s hostname, FQDN, or IP address, we’ve avoided the bug and provided more thorough protection than the -auto_login_local option provides anyway.

And of course we could have used instead of localhost – the results are the same.

Finally, remember that the connection string forms the primary key of the 3DES protected data in the Wallet file which can’t be modified without knowing the Wallet’s password.


Connecting Through a Dedicated Listener and “Valid Node Checking”

Another way to prevent the Oracle Wallet from being used to access the database from an unauthorized server (actually any server other than the DB server) is to have the scripts connect through a dedicated listener. The dedicated listener’s port can then be restricted using either a firewall or the listener’s “valid node checking” functionality.

For example, the dedicated listener could be configured with the following in the listener.ora file:

    (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1599)))
    (SID_DESC =
      (ORACLE_HOME = /u01/app/oracle/product/12.1.0/dbhome_1)
      (SID_NAME = ORCL)


Then for added (though possibly redundant due to the use of localhost) protection, the following entries could be adding to the server’s sqlnet.ora:

TCP.INVITED_NODES = (localhost)


As a result, local connections using localhost:1599/ORCL will work, while connections from the compromised server, connections will receive:

ORA-12537: TNS:connection closed



Preventing Use by Another OS User

Another challenge is to prevent another OS user on the same server from using the Oracle Wallet to connect to the database.

Of course the wallet files should be well secured using OS directory and file security. It can further be obfuscated by making the wallet directory a hidden directory (starting with a period).

If the -auto_login_local option is used then other users on the same server will not be able to use the Oracle Wallet credentials and instead will get the “ORA-12578: TNS:wallet open failed” error. Hence, creating the Oracle Wallet using a version other than (regardless of the database version) and enabling the -auto_login_local option is still the best solution.

Beyond OS directory and file restrictions and the -auto_login_local option, the only other method for restricting access from other OS users on the same server would be a database scoped logon trigger or secured application role.



Using an Oracle Secure External Password Store (SEPS) and Oracle Wallet files is the best way to handle database credentials and passwords in OS scripts. However, a number of significant problems exist:

  1. The -auto_login_local parameter can be bypassed on a compromised server by changing the hostname (in /etc/hosts and /etc/hosts/network).
  2. The -auto_login_local parameter doesn’t work at all when created with software.


That being said, we can still harden our script’s database access by following some additional suggestions:

  • Create the Oracle Wallet using or software even if connecting to databases.
  • If the Oracle Wallet files were created using or, protect from usage by other users by using the -auto_login_local parameter.
  • Prevent use from other servers by not using an OracleNET Service Name in Oracle Wallets and instead using an EZconnect connection string using either localhost or (not the proper DB server’s hostname, FQDN, or IP address).
  • Another strategy is to use a dedicated listener on a dedicated port with listener “valid node checking” to only permit connections from the local server.
  • As a last resort prevent non-authorized IPs or OS Users from connecting using a logon trigger or secure application role within the DB.


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Categories: DBA Blogs

Securing Oracle Monitoring and Backup Scripts

Fri, 2016-01-15 14:41

Almost every DBA writes and uses various custom scripts to monitor and backup their Oracle databases. However, finding the optimal and most secure way to connect to the database is often not prioritized.

The short summary is that having your script put the username/password (credentials) in any sort of variables or command arguments is the “bad way”. Using an “Oracle External Password Store” (SEPS) or Oracle Wallet is the “better way”. Yet this technology which has been around since Oracle 10gR2 and which does not require the Advanced Security Option is often not used.


Common Mistakes

Many DBAs will store credentials in their actual scripts. Sometimes obfuscating the actual password through some custom mechanism or script. For example, the following is a simplified version of an RMAN backup script found at a client site:

export DB_USER=backup_user
export DB_PASS=`~/.secure_pwd_extractor`

$ORACLE_HOME/bin/rman << EOF
   connect target $DB_USER/$DB_PASS
   shutdown immediate
   startup mount
   backup database;
   alter database open;


The client thought that it was somewhat secure as the actual password wasn’t used as a command line argument to RMAN and was stored in a Linux “hidden file” (starts with a period), which was protected by properly setting OS permissions. However, it dynamically extracted the password from a plain text file (based on the DB_USER environment variable). Another key problem was the fact that the environment variable was exported and hence was part of the environmental profile under which the database was started.

The exported environment variables in this case can be a little bit of a security risk in a couple of ways:

First of all, the complete operating environment including the exported environment variables under which the database is running are recorded by the listener when service is registered. Hence, they are visible in a listener “services” command with “set displaymode verbose“:


Secondly, they may be recorded in OS process files. For example, the pmon process’ operating environment or even the RMAN process’ while running:



But most significantly the credentials can be extracted by anyone with access to the script file and/or the underlying credentials file.


A Better Approach

A better way to store database credentials for monitoring or backup scripts is to use a “Secure External Password Store” (SEPS) which relies on having the necessary credentials securely stored in an Oracle Wallet file.

Typically a DBA might create their own plain text password listing file for use by scripts and batch jobs. Usually with three columns: 1) DB_NAME; 2) DB_USERNAME; 3) DB_PASSWORD. The Oracle Wallet is structured exactly the same way except:

  1. The file is protected with 3DES encryption.
  2. The DB_NAME is really an OracleNET Service Name meaning you can have multiple aliases for the same database.
  3. The passwords are never exposed.
  4. A separate Wallet password is required to manipulate the file’s contents.
  5. Control on whether the Oracle Wallet file is tied to the local machine or whether it can be copied to and used on other machines.


The advantages of this approach include:

  • No clear text password in any scripts or files.
  • No possible exposure of passwords by the listener or process operating environments.
  • Control on whether the Oracle Wallet file can be copied and used on another machine.


The last point is actually a complex one. A Wallet can be created as an “auto_login” wallet (done by default). To secure it to only work on the local server, it can be changed to “auto_login_local“. However, there are various issues, limitations, and 12c bugs with the additional functionality that Oracle provides. A separate article goes into this in detail.



Setting up a “Secure External Password Store” and Oracle Wallet is actually quite quick and easy:

1) Adjust the sqlnet.ora file to point to an Oracle Wallet location. For example, add the following to the sqlnet.ora file (assuming that the specified directory exists):

   (SOURCE =
     (METHOD = FILE)
       (DIRECTORY = /u01/app/oracle/wallet)


2) Create the Oracle Wallet files and add a credential. Two files will actually be created in the specified directory:

  • ewallet.p12 – the actual password protected Wallet file.
  • cwallet.sso – an additional file for auto-login credentials.


This can be done as either two separate commands or all in a single command:

$ mkstore -wrl "/u01/app/oracle/wallet" -create
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Enter password:
Enter password again:

$ mkstore -wrl "/u01/app/oracle/wallet" -createCredential ORCL scott
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Your secret/Password is missing in the command line
Enter your secret/Password:
Re-enter your secret/Password:
Enter wallet password:
Create credential


Or as a single command:

$ mkstore -wrl "/u01/app/oracle/wallet" -create -createCredential ORCL scott
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Enter password:
Enter password again:
Your secret/Password is missing in the command line
Enter your secret/Password:
Re-enter your secret/Password:
Create credential


Notice that the Wallet is secured by a password. And then the SCOTT credentials are stored within the Wallet. The Wallet password is required to manipulate contents – not for scripts to access the stored credentials.

The first parameter after the “-createCredential” argument is an OracleNET Service Name. Just like with any database connection, here we can specify an OracleNET Service Name (from the tnsnames.ora file), or a full connection string, or an EZconnect string.

Hence, we could add a second and third connection to the same database as:

$ mkstore -wrl "/u01/app/oracle/wallet" -createCredential localhost:1521/ORCL monitoring_user
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Your secret/Password is missing in the command line
Enter your secret/Password:
Re-enter your secret/Password:
Enter wallet password:
Create credential

$ mkstore -wrl "/u01/app/oracle/wallet" -createCredential batch_reporting
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Your secret/Password is missing in the command line
Enter your secret/Password:
Re-enter your secret/Password:
Enter wallet password:
Create credential



And to list the contents of the Oracle Wallet:

$ mkstore -wrl "/u01/app/oracle/wallet" -listCredential
Oracle Secret Store Tool : Version
Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:
List credential (index: connect_string username)
3: batch_reporting
2: localhost:1521/ORCL monitoring_user
1: ORCL scott


Now any of the three can be used (from the same OS account: “oracle”) depending on which OracleNET Service Name is referenced:

$ sqlplus /@ORCL

SQL*Plus: Release Production on Wed Jan 13 08:59:12 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Last Successful login time: Wed Jan 13 2016 08:56:56 -07:00

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> show user
$ sqlplus /@localhost:1521/ORCL

SQL*Plus: Release Production on Wed Jan 13 08:59:41 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Last Successful login time: Wed Jan 13 2016 08:57:25 -07:00

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> show user

$ sqlplus /@

SQL*Plus: Release Production on Wed Jan 13 09:00:14 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Last Successful login time: Wed Jan 13 2016 08:43:44 -07:00

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> show user
$ sqlplus / as sysdba

SQL*Plus: Release Production on Wed Jan 13 09:01:12 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

Connected to:
Oracle Database 12c Enterprise Edition Release - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> show user


However, one might challenge the fact that the Oracle Wallet file itself that must be secured just as a plain text password file would need to be and that the risks of either being obtained by a “bad actor” are the same. That being said, there are still some benefits of the SEPS method:

  • Passwords are never maintained in plain text in scripts or (hidden) password files.
  • No risk of password exposure at the operating system process list.
  • No risk of password exposure in operating system process environmental files.
  • No risk of exposure from any bad actor with access to the script.
  • No risk of password exposure in OS backups maintained by sysadmins or backup vendors (though the files themselves may still be usable).

Regardless, using the SEPS and Oracle Wallet shouldn’t make anything less secure. One could argue that security and risk is equal, but definitely not worse.

However they are a few operational disadvantages:

  • The OracleNET Service Name forms the primary key of the entries in the Wallet and hence must be unique. So if another user credential is required for the same DB, an OracleNET alias will be required (as trying to add another user using the same OracleNET Service Name will generate the “Credential already exists” error based on the OracleNET Service Name not being unique).
  • Doesn’t work after connecting to SQLPLUS using the “CONNECT” command.
  • Scripts are now dependent on listener availability for establishing a TNS connection instead of a BEQ. Though a workaround may be to connect directly to a DISPATCHER port.


Advantages Over OS Authentication

Using a SEPS and an Oracle Wallet may seem functionally similar to just using “OS Authentication”. However it does pose a few differences or advantages.

Most DBAs operate and implement scripts under the “Oracle software owner” account which is typically called “oracle” on Unix or Linux systems. And hence most are able to connect to the database using a SYSDBA connection. So one solution would be to use a dedicated OS user account specifically for monitoring or database backup scripts. And then rely on OS authentication for database connections. However this is often not done. And if running scripts from a remote server or centralized monitoring server then the REMOTE_OS_AUTHENT=TRUE parameter would have to be set which poses other security risks.

Instead, using a SEPS allows for non-OS authenticated connections to a dedicated and minimally privileged database account even from the software owner (Oracle) account locally, or from any other account remotely.


Other Questions

Q: Do I need to re-create my Wallet file as part of a 12c upgrade?
A: NO.

Q: Do I need to backup the Wallet files?
A: Absolutely. Just back them up as you would other Oracle environmental files, such as the sqlnet.ora. Otherwise they’ll need to be re-created.

Q: Is SEPS compatible with “Proxy Authenticated Connections”?
A: YES. See Proxy Authenticated Database connections

Q: Can the Wallet be used with RMAN?
A: YES. It definitely can and should be used by RMAN scripts.

Q: Can the Wallet be used with JDBC thin or ODBC connections?
A: YES to both. See MOS documents 1441745.1 and 1430666.1 for further details.

Q: Are SEPS and Wallet connections compatible with the CDB architecture and PDBs?
A: Of course. PDBs connect through Oracle Services and OracleNET Service Names.

Q: Can we tell from within the database whether a connected session referenced an Oracle Wallet and used SEPS?
A: NO. There doesn’t seem to be any indication from within the database. As far as the DB is concerned, it just seems to be a password authenticated connection. A SQLNET trace shows that the Wallet files are accessed but doesn’t transpose that information into any DB metric or SYS_CONTEXT USERENV data.


Preventing the Secure Password Store Wallet File from Being Moved to Another Host

Oracle suggests that we can add additional security by tying the Oracle Wallet file to a specific host. See MOS document 1114599.1. However, this poses some restrictions and bugs with specifically. As this discussion is complex, this follow-up article has been created.

A good workaround (and a key point from the follow-up article) is to simply use an EZconnect connection in the Oracle Wallet file and to specify localhost or


Summarizing Best Practices
  • Continue to properly secure the directory and file permissions of the Wallet files as you would a plain text password file. Further, why not make the entire wallet directory a hidden directory starting with a period. Remember that If the wallet file can be copied to another server then potentially the credentials within it can continue to be used. See the follow-up article for suggested techniques for securing access further.
  • Have scripts connect to the database using dedicated purpose based user accounts with minimal privileges (don’t use SYS or SYSTEM).
  • Use OracleNET Service Name aliases (not duplicate entries, but aliases to an existing entry) in the tnsnames.ora file to allow multiple credentials for the same database.
  • For additional security add Wallet entries based on EZconnect strings using localhost or instead of relying on OracleNET Service Names from the tnsnames.ora file.


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Categories: DBA Blogs

Log Buffer #457: A Carnival of the Vanities for DBAs

Fri, 2016-01-15 14:19

This Log Buffer Edition begins with some great blog posts from Oracle, goes through SQL Server and then ends with MySQL.


  • Ruby-oci8 is a ruby interface for an Oracle Database.
  • Another python graph – one wait event.
  • This article compares FBL and HDL – two of the commonly used data loading tools in Fusion HCM to highlight key differences and similarities.
  • Better Data Modeling: Customizing Oracle Sql Developer Data Modeler (#SQLDevModeler) to Support Custom Data Types.
  • Sample code: Oracle Grid Infrastructure action script for Windows.

SQL Server:

  • Being a database administrator can be very challenging at times when you have to troubleshoot performance issues.
  • Another Reason to Use NOEXPAND hints in Enterprise Edition.
  • Error: Microsoft .NET framework 3.5 service pack 1 is Required.
  • Removing Duplicates from Strings in SQL Server.
  • .NET Core is more interesting than the name might suggest. Whereas the .NET framework provides a consistent runtime for all the applications on a machine.


  • OpenSSH CVE-2016-0777: Details and Mitigation.
  • MySQL Group Replication for MySQL 5.7.10.
  • MySQL 5.7 auto-generated root password.
  • MySQL Support People – Those Who Were There First.
  • Planning the defaults for MySQL 5.8.


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Categories: DBA Blogs

Configure High Availability – Load Balancing for Hiveserver2

Tue, 2016-01-12 15:21
We are noticing a steady adoption of Hive adoption among our customers. Due to the increased workload we want to make sure that performance and availability of Hive is not compromised. The following steps will ensure the smooth functioning of Hive under increased workloads.

Configuring High Availability for Hive requires the following components to be fail proof:

1. Hive Metastore underlying RDBMS
2. Zookeeper
3. Hive Metastore Server
4. Hiveserver2

For the sake of simplicity this blog will focus on enabling HA for the Hive Metastore Server and HiveServer2. We recommend that the underlying Hive Metastore underlying RDBMS be configured for High Availability and we have configured multiple Zookeeper instances on the current cluster.

Enabling High Availability for Hive Metastore Server1. Log on to Cloudera Manager2. Click on HIVE > Hive Metastore Server. Locate the host for the Hive Metastore Server.


3. SSH to Hive Metastore Server.# vi /etc/hive/conf.cloudera.hive/hive-site.xmlExpected Output below.


4. On the Cloudera Manager Console click Hive > Configuration

Select Scope > Hive Metastore Server.
Select Category > Advanced.
Locate the Hive Metastore Delegation Token Store property.
Choose org.apache.hadoop.hive.thrift.DBTokenStore
Click Save Changes.


5. On the Cloudera Manager Console click Hive > Instances. Click on Add Role Instances.

Click on Select Hosts for Hive Metastore Server.


6. Choose multiple Hosts (at least 2 more to make a total of 3) to configure Hive Metastore Server on.

Click OK and Continue.


7. Click Finish. You should now see new hosts added as the Hive Metastore Server.Click on Restart the service (or the instance) for the changes to take effect.


8. Notice that hive.metastore.uris now has multiple instances of Hive Metastore Server.

Click on Restart Stale Service.


9. Click Restart Now.


10. Review Restart Messages.


11. Notice that you now have multiple instances of Hive Metastore Server.


12. SSH again to Hive Metastore Server.# vi /etc/hive/conf.cloudera.hive/hive-site.xmlExpected Output below. Note that new instances have been added.


So how do you know the settings are working? The following is the recommended plan for testing the High Availability of Hive MetaStore.1. SSH to any DataNode. Connect to Hiveserver2 using Beeline.

# beeline -u “jdbc:hive2://ip-10-7-176-204.ec2.internal:10000”


2. On the Cloudera Manager Console click Hive > Hive MetaStore Server.Stop the first Hive MetaStore Server in the list.


Issue “Show databases” command in the beeline shell of step 1. The command should work normally.

3. Stop the second Hive Metastore Server in the list. Issue Show databases command in the beeline shell of step 1.The command should still work normally.

4. Stop the third Hive Metastore Server in the list. Issue Show databases command in the beeline shell of step 1.This command should fail which is normal.


Expected Output from beeline below.


5. Now start a random Hive Metastore Server in the list. Issue Show databases command in the beeline shell of step 1.This command should start working normally again.

6. After testing it completed make sure you start all Hive Metastore Servers in the list.

Enabling Load Balancing and High Availability for Hiveserver2To provide high availability and load balancing for HiveServer2, Hive provides a function called dynamic service discovery where multiple HiveServer2 instances can register themselves with Zookeeper. Instead of connecting to a specific HiveServer2 directly, clients connect to Zookeeper which returns a randomly selected registered HiveServer2 instance.

1. Log on to Cloudera Manager.Click Hive > Instances. Click on Add Role Instances.

Click on Select Hosts for HiveServer2.


2. Choose multiple Hosts (at least 2 more to make a total of 3) to configure HiveServer2 on.

Click OK and Continue.


3. You should now see new hosts added as HiveServer2.

Choose the newly added instances and Choose Start.


4. Click on Close. The newly added HiveServer2 instances are now ready for use.


5. Open Hive -> Configuration -> Category -> Advanced.Find “HiveServer2 Advanced Configuration Snippet (Safety Valve) for hive-site.xml”
Add a new property as below:

Value: true


6. Go to the Cloudera Manager Home Page and Restart Hive Service.


7. You should now have multiple instances of HiveServer2.


So how do you know the settings are working? Following is the recommended plan for testing the Load Balancing for Hiveserver2.

1. As mentioned before HiveServer2 High Availability is managed through Zookeeper.


The clients connecting to HiveServer2 now go through Zookeeper. An example, JDBC connect string is as follows. Notice that the JDBC now points to a list of nodes that have Zookeeper on them.

beeline -u “jdbc:hive2://ip-10-7-176-204.ec2.internal:2181,ip-10-229-16-131.ec2.internal:2181,ip-10-179-159-209.ec2.internal:2181/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=hiveserver2”

2. SSH to any data node. Connect to Hiveserver2 using Beeline.# beeline -u “jdbc:hive2://ip-10-7-176-204.ec2.internal:2181,ip-10-229-16-131.ec2.internal:2181,ip-10-179-159-209.ec2.internal:2181/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=hiveserver2”


3. The connection gets routed to the HiveServer2 instances in a round robin fashion.

Issue the following command on the HiveServer2 nodes.

# tail -f /var/log/hive/hadoop-cmf-hive-HIVESERVER2-ip-10-7-176-204.ec2.internal.log.out

Issue the following command on the HiveServer2 nodes.


4. You may issue the beeline command from multiple sources and monitor the HiveServer2 logs.


So how do you know the settings are working? Following is the recommended plan for testing the High Availability for Hiveserver2.

1. On the Cloudera Manager Console click Hive > HiveServer2.Stop the first HiveServer2 in the list


Connection to Beeline using command below should work normally.

# beeline -u “jdbc:hive2://ip-10-7-176-204.ec2.internal:2181,ip-10-229-16-131.ec2.internal:2181,ip-10-179-159-209.ec2.internal:2181/;serviceDiscoveryMode=zooKeeper;zooKeeperNamespace=hiveserver2”

2. Stop the second HiveServer2 in the list


Connection to Beeline using command below should still work normally.

3. Stop the third HiveServer2 in the list.


Connection to Beeline using command below should fail.


4. Start the third HiveServer2 in the list.


Connection to Beeline using command below should work normally again.

5. After the testing completes make sure you start all HiveServer2 in the list.


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Categories: DBA Blogs

Log Buffer #456: A Carnival of the Vanities for DBAs

Tue, 2016-01-12 07:38

This Log Buffer Edition covers many aspects discussed this week in the realms of Oracle, SQL Server and MySQL.


  • Oracle and Informatica have a very close working relationship and one of the recent results of this collaboration is the joint project done by Informatica and our Oracle ISV Engineering team to test the performance of Informatica software with Oracle Database 12c In-memory on Oracle SPARC systems.
  • The only thing you can do easily is be wrong, and that’s hardly worth the effort.
  • Enterprise Manager 13c: What’s New in Database Lifecycle Management.
  • SnoopEE is a very interesting grass roots open source Java EE ecosystem project. Akin to NetFlixOSS Eureka it enables microservices discovery, lookup and registration.
  • Docker is an open source container technology that became immensely popular in 2014. Docker itself is written in Google’s programming language “Go” and supported on all major Linux distributions (RedHat, CentOS, Oracle Linux, Ubuntu etc.).

SQL Server:

  • This blog helps you understand Graphical Execution Plans in SQL Server.
  • New DAX functions in SQL Server 2016.
  • JSON support in SQL Server 2016.
  • PowerShell Tool Time: Building Help.
  • Datetime vs. Datetime2.


  • Peter Gulutzan discusses SQL qualified names.
  • It is not new that we can store a JSON content in a normal table text field. This has always been the case in the past. But two key features were missing: filtering based on JSON content attributes and indexing of the JSON content.
  • MySQL 5.7 Multi-Source Replication – Automatically Combining Data From Multiple Databases Into One.
  • OOM killer vs. MySQL 5.7.10 epic results with over-allocating memory.
  • Apache Spark with Air ontime performance data.


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Categories: DBA Blogs