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Log Buffer #373, A Carnival of the Vanities for DBAs

Pythian Group - Fri, 2014-05-30 07:22

There are many ways to express the knowledge learned but nothing is better than a comprehensive and concise blog post. This Log Buffer Edition gathers such blog posts across Oracle, SQL Server and MySQL.


It’s All About CPU But There Is NO CPU Bottleneck! What?

Understanding the Value of SOA

Java Magazine: Developer Tools and More

The Evolution of Oracle Forms Survey: Results are In!

Australian Oracle job market status update is out.

FAST Refresh of Materialized View Returns ORA-12004

SQL Server:

Learn how relationships work in Powerpivot workbooks and how you can build them using the DAX language.

Branching and Merging: Ten Pretty-Good Practices

Survey: Which new database platforms are you adopting?

Stairway to SQLCLR Level 3: Security (General and SAFE Assemblies)

Free eBook: SQL Server Execution Plans, Second Edition

Transparent Data Encryption (TDE) in SQL Server


MariaDB 10.0.11 Overview and Highlights.

Webinar-on-demand: Set up & operate real-time data loading into Hadoop

Using MySQL Sandbox to setup a MySQL Fabric cluster in development

How MySQL ‘queries’ and ‘questions’ are measured

From zero to full visibility of MySQL in 3 minutes with Percona Cloud Tools

There is one new feature in MySQL 5.6 that didn’t get the attention it deserved

Categories: DBA Blogs

12c: USE_SID_AS_SERVICE_listener_name

Oracle in Action - Fri, 2014-05-30 03:58

RSS content

In an Oracle 12c container database, the client must specify a service name in order to connect to the PDB. Many  Database clients with earlier releases of Oracle Database might have hard-coded connect descriptors to use SID to connect to the database. Now if they choose to plug in their non-CDB’s into a CDB, they will have to modify the connect descriptors in tnsnames.ora on all the client sites.

This problem can be resolved by the use of listener.ora parameter USE_SID_AS_SERVICE_listener_name.  Setting this parameter to on instructs the listener to use the SID in the connect descriptor as a service name and connect the client to the specified database. The default value for this parameter is off and it has to be explicitly set to on to use this functionality.

Here is the demonstration :

Presently, I have a CDB called CDB1 into which I have plugged in a non-CDB (ncdb).

SQL> sho parameter db_name

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_name                              string      cdb1
SQL> sho pdbs

---------- ------------------------------ ---------- ----------
2 PDB$SEED                       READ ONLY  NO
3 NCDB                           READ WRITE NO

Currently connect descriptor in tnsnames.ora entry for ncdb points to SID as follows:

(SID = ncdb)

In listener.ora , since there is no entry for USE_SID_AS_SERVICE_listener_name, it defaults to off.


– If I try to connect to NCDB, I get following error :

[oracle@host01 ~]$ export ORACLE_SID=ncdb
[oracle@host01 ~]$ sqlplus system/oracle@ncdb

SQL*Plus: Release Production on Fri May 30 15:24:00 2014

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

 ORA-12505: TNS:listener does not currently know of SID given in connect

– I  edited  listener.ora to set USE_SID_AS_SERVICE_LISTENER to on


[oracle@host01 admin]$ lsnrctl reload

[oracle@host01 admin]$ lsnrctl stat

LSNRCTL for Linux: Version - Production on 30-MAY-2014 15:24:55

Copyright (c) 1991, 2013, Oracle.  All rights reserved.

Alias                     LISTENER
Version                   TNSLSNR for Linux: Version - Production
Start Date                29-MAY-2014 11:03:14
Uptime                    1 days 4 hr. 21 min. 40 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/oracle/product/12.1.0/db_1/network/admin/listener.ora
Listener Log File         /u01/app/oracle/diag/tnslsnr/host01/listener/alert/log.xml
Listening Endpoints Summary...
Services Summary...
Service "cdb1" has 1 instance(s).
Instance "cdb1", status READY, has 1 handler(s) for this service...
Service "cdb1XDB" has 1 instance(s).
Instance "cdb1", status READY, has 1 handler(s) for this service...
Service "em12rep" has 1 instance(s).
Instance "em12rep", status READY, has 1 handler(s) for this service...
Service "em12repXDB" has 1 instance(s).
Instance "em12rep", status READY, has 1 handler(s) for this service...
Service "ncdb" has 1 instance(s).
 Instance "cdb1", status READY, has 1 handler(s) for this service...
The command completed successfully

– Now I can connect  to NCDB easily ..

[oracle@host01 ~]$ sqlplus system/oracle@ncdb

SQL> sho con_name


Hope this post was useful.

Your comments and suggestions are always welcome!!



Related Links:


Database 12c Index

12c : Connecting to CDB/PDB – Set Container vs Connect
12c : Connecting To PDB’s With Same Name






Comments:  0 (Zero), Be the first to leave a reply!You might be interested in this:  
Copyright © ORACLE IN ACTION [12c: USE_SID_AS_SERVICE_listener_name], All Right Reserved. 2014.

The post 12c: USE_SID_AS_SERVICE_listener_name appeared first on ORACLE IN ACTION.

Categories: DBA Blogs

It's All About CPU But There Is NO CPU Bottleneck! What?

It's All About CPU But There Is NO CPU Bottleneck...
Diagnosing Oracle Database performance is like solving a puzzle. But what I really enjoy is coming up with performance solutions that are anti-intuitive for most people. You know, the ones when you can see people stop talking and actually think, "Why would Craig say that!?" In this posting, I delve into one of these situations.

The Situation
Just over a month ago I received an email from a former Australian Oracle Performance Firefighting student about their "CPU bottleneck." Based on an one-hour AWR report's Time Model Statistics section (which is based on v$sys_time_model view), the  DB CPU was 95% of DB Time, leaving 5% for Oracle wait time. The top CPU consuming SQL statements were easily identified and work had begun with tuning them. By "tuning" I mean a small group of DBAs were working to reduce their CPU consumption. But something didn't feel right to him, so he emailed me about it.

My first question was, "Is there an OS CPU bottleneck?" That is, is the host (or virtual machine if you like) out of CPU resources? I was wondering if the average CPU utilization was 80% or higher. Why was I asking this? Read on...

DB Time Math
Over an interval of time, DB Time is all the Oracle server process CPU time (i.e., DB CPU) plus all the non-idle wait time.

Note: Oracle does not include background process CPU in DB Time. Why they don't include background process CPU time is an entirely different subject. And of course, we are trusting Oracle that what they consider "non-idle" wait time should actually be "non-idle" wait time. Again, that's an entirely different subject.

My former student knew the DB Time math and therefore understood that since DB CPU was pretty close to DB Time, there was little non-idle wait time. It was "all about CPU." While I still wanted to know the wait event situation because it provides performance hindering clues and forces the DBA to review their work and think a little more.

OS CPU Utilization Math
In my Utilization On Steroids online video seminar, I demonstrate utilization math by shrinking myself down to the size of a water glass and also the size of a printer cartridge. (Like the motto says, "What Online Training Should Be!") In a nutshell, utilization can be viewed/understood as requirements divided by capacity. If a 500ml glass contains 250ml of water, the glass is 50% utilized that is, 50% full.

As I present in my online seminar, there are two simple methods to figure OS CPU utilization using only the v$osstat view. One of these methods as based on the BUSY_TIME and the IDLE_TIME statistics from the Operating System Statistics section of any AWR and Statspack report. The BUSY_TIME is the instance CPU consumption, that is, the CPU requirements. As I carefully explain in my seminar and in my classes, the capacity is actually equal to the BUSY_TIME plus the IDLE_TIME. That is:

Utilization = Requirements / Capacity

Utilization =  BUSY_TIME / ( BUSY_TIME + IDLE_TIME )

This is true unless the OS is updating OS structures incorrectly (e.g., /proc) or Oracle is not gathering the data from the OS correctly or frequently enough. And yes, I talk about how to check this in my seminar.

My former student did the utilization math. The average utilization was around 65%. Since this is the only Oracle instance doing any real work on the box, is was not a surprise to him that vmstat also indicated the OS CPU utilization was 65%.

Why I Asked About A CPU Bottleneck?
Suppose there is plenty of available CPU resources AND the SQL users are complaining about are doing nothing but buffer gets (i.e., logical reads). In other words, from a resource consumption perspective, it's all about CPU consumption. Is this possible? The answer is, YES!

If there was a single server process running this SQL statement, parallel query operations were not occurring and there are four CPU cores, what would the CPU utilization be? Probably around 25% (plus overhead between 5% to 15%). That is because on average only one CPU core was processing the SQL statement!

If this SQL statement took "too long to run" adding more CPU power (specifically more cores) would not help.

As strange at it may seem, one performance improving solution is to use the available CPU! Read on.

Use More CPU! Now!
Suppose the average CPU utilization of a 10 CORE box (or VM if you prefer) was running at an average of 50% utilization. This means that on average 5 of the 10 cores are busy. Now suppose a SQL statement takes 4 minutes to process without parallel query or very-cool (but perhaps costly) application design. How long would the SQL statement take to run if it ran in four parallel streams?

It depends. We need to ensure there is available CPU power. Assuming each parallel stream consumes one CPU core, the box has 10 cores with 5 being available (remember the average utilization is 50%), that leaves with us 5 "extra" cores. For our SQL statement to run in 4 parallel streams, we need three more CPU cores... and we have them!

If there is no parallelism overhead (ha! don't count on that!), the SQL statement would run in around 1 minutes, 8 CPU cores would be active (5+3), and the average CPU utilization would be around 80% (8 cores required / 10 cores of capacity).

So by creatively using available CPU resources, we were able to consume 4 minutes of CPU in a single minute! ...a beautiful example of parallelism. And of course, the users will be delighted and I may get a free pizza.

Be Anti-Intuitive
When a SQL statement, batch process or an Oracle process is constrained by CPU, yet there is plenty of CPU power available, the problem is probably a serialization issue. (Another possibility is some type of locking or blocking problem.) The solution can be found by parallelizing, thereby using the available CPU resources which will reduce the wall/clock/run time of the process.

If the above paragraph makes sense, then you understand what I'm talking about. If it does not make sense, stop, breath, and re-read the previous paragraph or paragraphs. It will be worth your time.

This next paragraph is really important to understand:

It is important to understand we have NOT reduced the total SQL statement's CPU requirements. We have NOT increased the total SQL statement's CPU requirements. We have NOT tuned the SQL statement in the traditional sense by reducing the buffer gets (logical reads, logical IOs). What we have done is simply altered the situation by consuming the necessary CPU requirements within a shorter duration. (In our example, the four minutes of CPU time was consumed within a single minute.) We did this taking a serial process and parallelizing it to use more of the available CPU resources.

Expand Our View Into The OS
Without understanding the OS situation we can easily misdiagnose the problem. And we can miss creative and powerful solutions.

Most DBAs immediately jump to tuning the SQL and tuning Oracle. While those are both valid technical solutions, there are others... like parallelizing to reduce run time while consuming more resources (in a shorter period of time).

Some DBAs but more likely OS Administrator but for sure hardware vendors may insist on getting more CPU power. While faster CPU will help somewhat, adding more of the same CPUs cores will likely do absolutely nothing...unless we can increase parallelism to use them.

Being able to determine the OS bottleneck is so important, I devote an entire chapter in my Oracle Performance Firefighting book on the subject. When I was learning to optimize Oracle systems, learning how to find the OS bottleneck significantly increased my value in the Oracle DBA market. Later when I ruminated on serialization and parallelization, I turned situations upside down by placing a larger (yet shorter-term) load on the system as a valid performance improving solution.

If performance is not what it needs to be AND there are available OS resources, consider using them to improve performance. It's a creative and rarely used solution.

Thanks for reading!


If you enjoy my blog, I suspect you'll get a lot out of my online or in-class training. Go to I also offer on-site training and consulting services.

P.S. If you want me to respond to a comment or you have a question, please feel free to email me directly at craig@orapub .com. Another option is to send an email to OraPub's general email address, which is currently info@ orapub. com. can watch seminar introductions (like above) for free on YouTube!
Categories: DBA Blogs

First draft Sudden SQL Slowness Toastmasters talk

Bobby Durrett's DBA Blog - Thu, 2014-05-29 15:23

I’m doing Toastmasters to try to improve my speaking and my third talk will be related to why a function on a web site can suddenly slow down due to a change in plan.  It has to be 5 to 7 minutes long and the audience is non-technical.

So, just for fun, here is my first draft.  If you feel like giving me any suggestions that would be great.

First draft of Toastmasters Sudden SQL Slowness talk

- Bobby

Categories: DBA Blogs

From Las Vegas to Ottawa

Pakistan's First Oracle Blog - Wed, 2014-05-28 21:16
After a very engaging session at Collaborate14 in sunny Las Vegas amidst the desert of Nevada, I just arrived in not-so-bitterly cold Ottawa, the capital of Canada. Looking forward meeting with various Pythian colleagues and hanging out with the friends I cherish most.

My Exadata IORM session went well. Lots of follow back discussion plus questions are still pouring in. I promise I will answer them as soon as I return to Australia after couple of weeks. That reminds me of my flight from one corner of the globe to the other, but well I need to learn as how to sleep like a baby during flights. Any ideas?

Ottawa reminds me of Australian capital Canberra. It's quite a change after neon-city Vegas. Where Vegas was bathing in lights, simmering with shows, bubbling with bars, swarming with party-goers, and rattling with Casinos; Ottawa is laid-back, quiet, peaceful, and small. Restaurants and cafes look cool. Ottawa River is mostly still frozen and mounds of snow are evident along the road sides with leafless trees.

But spring is here, and things look all set to rock.
Categories: DBA Blogs

SQL Profile appears to not work but really does

Bobby Durrett's DBA Blog - Wed, 2014-05-28 16:46

Over the weekend a coworker applied a SQL profile to a long running SQL statement but it looked like the profile was not applied.  For one thing, the SQL statement ran just as long after applying the profile.  Also, the hash value for the plan that the optimizer chose for the statement after applying the SQL Profile was not the same as the desired plan.  But, after looking at it today I’ve realized that the SQL Profile did apply the desired plan.  It was just that the desired plan wasn’t really any more efficient than the one picked by the optimizer.

Here are earlier posts related to our use of SQLT to force a given SQL statement to run with a good plan:

Using coe_xfr_sql_profile.sql to force a good plan

SQLT Emergency Plan Change

In this weekend’s case we were looking at sql_id fpa2sb9pt9d6s.  It looked like plan 1394068771 was faster than the most recently used plan because it had a lower average elapsed time:

SQL_ID        PLAN_HASH_VALUE END_INTERVAL_TIME         EXECUTIONS_DELTA Elapsed Average ms CPU Average ms IO Average ms Cluster Average ms Application Average ms Concurrency Average ms Average buffer gets Average disk reads Average rows processed
------------- --------------- ------------------------- ---------------- ------------------ -------------- ------------- ------------------ ---------------------- ---------------------- ------------------- ------------------ ----------------------
fpa2sb9pt9d6s      1615990741 11-MAY-14 AM                1         21550951.2        9720630    467066.276                  0                  27.24              82825.793           126238536            1913606                      0
fpa2sb9pt9d6s      1394068771 18-MAY-14 PM                1         1687493.09         657760    402607.781                  0                 39.814               36561.61             4701985             566205                      0
fpa2sb9pt9d6s      1611789738 25-MAY-14 AM                1         11390629.8        6835390    462073.968                  0                 32.818              39010.945            86448768             993957                      0

So we used SQLT to force fpa2sb9pt9d6s to use plan 1394068771 but instead it appeared to use plan 420390762 and it didn’t run any faster:

SQL_ID        PLAN_HASH_VALUE END_INTERVAL_TIME         EXECUTIONS_DELTA Elapsed Average ms CPU Average ms IO Average ms Cluster Average ms Application Average ms Concurrency Average ms Average buffer gets Average disk reads Average rows processed
------------- --------------- ------------------------- ---------------- ------------------ -------------- ------------- ------------------ ---------------------- ---------------------- ------------------- ------------------ ----------------------
fpa2sb9pt9d6s      1615990741 11-MAY-14 AM                1         21550951.2        9720630    467066.276                  0                  27.24              82825.793           126238536            1913606                      0
fpa2sb9pt9d6s      1394068771 18-MAY-14 PM                1         1687493.09         657760    402607.781                  0                 39.814               36561.61             4701985             566205                      0
fpa2sb9pt9d6s      1611789738 25-MAY-14 AM                1         11390629.8        6835390    462073.968                  0                 32.818              39010.945            86448768             993957                      0
fpa2sb9pt9d6s       420390762 25-MAY-14 PM                1         19055402.5        8975130    492406.429                  0                  24.93              64279.331           120027479            1943256                      0

But if you look at the plan for fpa2sb9pt9d6s that has hash value 420390762 it says it is using the sql profile we created which should result in a plan with hash value 1394068771:

   - SQL profile "coe_fpa2sb9pt9d6s_1394068771" used for this statement

So, I dumped out both plans – 420390762 and 1394068771 and edited out the columns from the plan output that were irrelevant and did a diff and came up with this result:

< |  41 |                          TABLE ACCESS FULL      | SYS_TEMP_0FD9D67B9_9DB13F0D |       |       |  Q2,01 | PCWP |            |
> |  41 |                          TABLE ACCESS FULL      | SYS_TEMP_0FD9D6897_9DB13F0D |       |       |  Q2,01 | PCWP |            |

420390762 and 1394068771 were identical except that the system generated temporary segment name was slightly different.  The temp segment name affects the hash value for the plan so this is a gotcha on using plan hash value to compare plans.  Two distinct plan hash values could really represent the same plan if they have system generated temporary segments in the plan.

So, SQLT did successfully apply a given plan to a given sql_id using a SQL Profile but it didn’t improve performance and the resulting plan hash value was not what we expected.

- Bobby

Categories: DBA Blogs

Export data to excel

DBA Scripts and Articles - Tue, 2014-05-27 16:59

who never needed to export data to excel from sqlplus ? everybody had one day needed to do that. Sqlplus support the HTML markup which provides an excellent result once opened in excel. With the HTML markup, sqlplus create a table with all columns from your query including the name of your columns as table [...]

The post Export data to excel appeared first on Oracle DBA Scripts and Articles (Montreal).

Categories: DBA Blogs

Oracle Diagnostics Presentations

Hemant K Chitale - Mon, 2014-05-26 09:33
I've uploaded my Oracle Diagnostics Presentations from the years 2010-2011 into slideshare.

I hope that they are useful.

Categories: DBA Blogs

Elastic PaaS with WebLogic and OpenStack, part I

In my previous blog I described the steps to get OpenStack on Solaris up and running. Now we'll explore how WebLogic and OpenStack can work together to deliver truly elastic Middleware Platform as a...

We share our skills to maximize your revenue!
Categories: DBA Blogs

My Session Evaluation from Collaborate14 in Las Vegas Arrived :)

Pakistan's First Oracle Blog - Sun, 2014-05-25 17:56
Dear Fahd Chughtai,
Thank you for presenting at COLLABORATE 14 – IOUG Forum in Las Vegas, Nevada. We hope that you will consider presenting at future IOUG events. You can view your evaluation results for the following session below: 194-12c Multi-Tenancy and Exadata IORM: An Ideal Cloud Based Resource Management
Note: Session evaluations were based on a 1-5 scoring scale. (1 being the lowest and 5 being the highest)

Primary speaker was knowledgeable about the materialThe primary speaker's presentation skills were satisfactoryThe slides and materials presented in the session were satisfactoryThe agenda abstract and objectives were accurate to the session presentationI learned a lot of new information in this session.I can apply what I learned in this session to my jobOverall, how would you rate this session?4.334.334.67444.334.33
Categories: DBA Blogs

Unindexed foreign keys

DBA Scripts and Articles - Sun, 2014-05-25 16:09

Unindexed foreign keys can lead to bad database performance due to lock contention and full table scans performed on the child table. Here is a diagram which illustrate the situation: In this exemple Oracle needs to lock the entire employees table when the primary key of the departments table is modified, in addition to that [...]

The post Unindexed foreign keys appeared first on Oracle DBA Scripts and Articles (Montreal).

Categories: DBA Blogs

Oracle Database 12c: Partner Material

Oracle Database 12c offers the latest innovation from Oracle Database Server Technologies with a new Multitenant Architecture, which can help accelerate database consolidation and Cloud projects. ...

We share our skills to maximize your revenue!
Categories: DBA Blogs

no oracle for you this weekend ... does not make me grumpy

Grumpy old DBA - Sat, 2014-05-24 16:21
Taking a long three day weekend and going to ( try anyhow ) to not even log into work network and not read email or ... anything.  Wow that's some bold action eh?

Tomorrow going to be competing in the Cleveland feis ( Irish step dancing competition ) with both daughters.  We are competing in parent child with a three hand reel for the Leneghan Academy of Irish dance.  Probably may the be last time we compete together ( but hey who knows ) it has been like 6 years probably since our last one.

At one point in our families Irish dancing career we were very busy over the summers with travel to various different events competing.  Yes even me eventually doing solo's etc.  At one point I impressed a judge in Louisville with my treble jig ( hard shoe dance ) that even though I was the ONLY competitor in that event ... she awarded me second place.  Lots of old stories etc from that phase in our lives!

Wish us luck tomorrow we are going to need it ha ha!
Categories: DBA Blogs

List of SQL Server Databases in an Availability Group

Pythian Group - Fri, 2014-05-23 11:07

After migrating some databases to SQL Server 2012 and creating Availability Groups for some databases, we have noticed that some of our maintenance scripts were failing with the following error:

The target database (‘MyDB1′) is in an availability group and is currently accessible for connections when the application intent is set to read only. For more information about application intent, see SQL Server Books Online.

Databases that are part of an Availability group and play the secondary role can be read-only replica and therefore are not writable.

Those databases cannot be part of some of the out-of-the-box maintenance plans or other coded maintenance procedures.

For the out-of-the-box Maintenance Plans, there is an option in the Plan to choose the preferred replica. (Link)

Any code that requires writes in the database will not work.

How do we get the list of those databases so that we can exclude them/include them in our code?

So first,

How do we know that this instance is part of Availability Group(s):

ISNULL(agstates.primary_replica, '') AS [PrimaryReplicaServerName],
ISNULL(arstates.role, 3) AS [LocalReplicaRole]
FROM master.sys.availability_groups AS AG
LEFT OUTER JOIN master.sys.dm_hadr_availability_group_states as agstates
    ON AG.group_id = agstates.group_id
INNER JOIN master.sys.availability_replicas AS AR
    ON AG.group_id = AR.group_id
INNER JOIN master.sys.dm_hadr_availability_replica_states AS arstates
    ON AR.replica_id = arstates.replica_id AND arstates.is_local = 1


Name PrimaryReplicaServerName LocalReplicaRole (1=primary,2=secondary,3=none) AvGroup_1 MyServer01 2 AvGroup_2 MyServer02 1


How do we get some information about the databases in the Availability Group:

SELECT AS [AvailabilityGroupName],
ISNULL(agstates.primary_replica, '') AS [PrimaryReplicaServerName],
ISNULL(arstates.role, 3) AS [LocalReplicaRole],
dbcs.database_name AS [DatabaseName],
ISNULL(dbrs.synchronization_state, 0) AS [SynchronizationState],
ISNULL(dbrs.is_suspended, 0) AS [IsSuspended],
ISNULL(dbcs.is_database_joined, 0) AS [IsJoined]
FROM master.sys.availability_groups AS AG
LEFT OUTER JOIN master.sys.dm_hadr_availability_group_states as agstates
   ON AG.group_id = agstates.group_id
INNER JOIN master.sys.availability_replicas AS AR
   ON AG.group_id = AR.group_id
INNER JOIN master.sys.dm_hadr_availability_replica_states AS arstates
   ON AR.replica_id = arstates.replica_id AND arstates.is_local = 1
INNER JOIN master.sys.dm_hadr_database_replica_cluster_states AS dbcs
   ON arstates.replica_id = dbcs.replica_id
LEFT OUTER JOIN master.sys.dm_hadr_database_replica_states AS dbrs
   ON dbcs.replica_id = dbrs.replica_id AND dbcs.group_database_id = dbrs.group_database_id
ORDER BY ASC, dbcs.database_name


AvailabilityGroupName PrimaryReplicaServerName LocalReplicaRole DatabaseName SynchronizationState IsSuspended IsJoined AvGroup_1 MyServer01 2 MyDB1 2 0 1 AvGroup_1 MyServer01 2 MyDB2 2 0 1 AvGroup_1 MyServer01 2 MyDB3 2 0 1

So, for example,

If we would like to get the databases that are secondary in the Availability Group,  to be excluded when writes are required:

dbcs.database_name AS [DatabaseName]
FROM master.sys.availability_groups AS AG
LEFT OUTER JOIN master.sys.dm_hadr_availability_group_states as agstates
   ON AG.group_id = agstates.group_id
INNER JOIN master.sys.availability_replicas AS AR
   ON AG.group_id = AR.group_id
INNER JOIN master.sys.dm_hadr_availability_replica_states AS arstates
   ON AR.replica_id = arstates.replica_id AND arstates.is_local = 1
INNER JOIN master.sys.dm_hadr_database_replica_cluster_states AS dbcs
   ON arstates.replica_id = dbcs.replica_id
LEFT OUTER JOIN master.sys.dm_hadr_database_replica_states AS dbrs
   ON dbcs.replica_id = dbrs.replica_id AND dbcs.group_database_id = dbrs.group_database_id
WHERE ISNULL(arstates.role, 3) = 2 AND ISNULL(dbcs.is_database_joined, 0) = 1
ORDER BY  dbcs.database_name


DatabaseName MyDB1 MyDB2 MyDB3

Related Links:

Monitor Availability Groups (Transact-SQL)

AlwaysOn Availability Groups Dynamic Management Views and Functions (Transact-SQL)

AlwaysOn Availability Groups Connectivity Cheat Sheet (describing types of AG replicas and if connection or reads are allowed on secondary DB)

Backups on secondary replicas – Always ON Availability Groups

Categories: DBA Blogs

Life at Pythian as a MySQL DBA

Pythian Group - Fri, 2014-05-23 08:00

Several people have asked me in the last year what it is like to work for Pythian. There are many reasons for a question like this, depending on who is asking.

Some people are concerned about the fact I am working for a Canadian-based company.

This typically comes from some of my xenophobic North American peers. But let me assure you, it’s not bad! Pythian is based out of Canada, but has employees around the globe in more than 25 countries. It’s pretty impressive, because Pythian must comply with the work laws of each country.

When you’re first hired at Pythian, you’ll be invited to visit their global headquarters in Ottawa, Canada. This is a great opportunity to get to know your peers, as well as the history of the company and how it operates. The country is beautiful, even if you’re lucky enough to be hired during their winter. Overall, it’s not very different compared to working for any other company in my country, aside from the extreme cold weather and all the talk about hockey and curling.

Besides, I actually like hockey.

Some people are curious about what it’s like working from home.

Pythian is not my first experience working remotely. I have been telecommuting since 2005. I tell these people that it’s not for everyone. Working remotely takes hard work and self-discipline.

When I first transitioned from office-life to working remotely, it was brutal. My productivity plummeted; I rarely began real work before noon. You typically don’t have your boss hovering over your shoulder at home—If you want this, feel free to add a monitor on the wall behind you and make sure your boss uses a webcam.

A remote employee must treat the home office like a real office. That means no wandering to your desk in your pajamas, half asleep. Make a concerted effort to dress for work, just as if you’re going into the office. If you have to, take a drive around the block as part of your commute!

If you have family or friends living with you, make sure they know that while you may be physically in the building, you are off limits except in emergencies.

Communication with colleagues can be challenging, and despite technology, your organization must develop an attitude with dealing with remote employees. At my first company I was among two people working remotely, and staying in the loop was like pulling teeth. Pythian on the other hand, is built with a large portion of its workforce being remote. The company is growing rapidly, and so must its policies. It is a major focus to ensure that all employees are kept up-to-date and in the loop. Communication lines are open using appropriate technologies such as Skype and Google Hangouts ensuring that team members are engaged with each other.

Some people are interested in the type of work I do as a MySQL consultant.

This is the conversation I love to have. Most often it comes from someone I met on the internet, and that’s ok. The best thing about working at Pythian is the sheer amount of technologies I get to work with on a daily basis.

As a MySQL Consultant at Pythian, I deal with customers running MySQL 4.1 through 5.6, Percona Server and MariaDB variations, Galera, Tungsten Replicator and many other solutions to solve some of the internet’s toughest problems. Our clients run datasets from a few gigabytes to multiple terabytes. Our clients run on different operating systems: Solaris, FreeBSD, all flavors of Linux, and even Windows in some cases. Our clients use filesystems ranging from ext2 to xfs and zfs, although we try really hard to persuade against ext2. We provide consulting for environments running on many of the cloud providers and hosting providers. We develop proof of concepts, migration and upgrade plans, performance tuning, capacity planning, high availability and disaster recovery plans, and much more.

Let’s face it: The open source world is ever-changing and new technologies are always being created to interact with the MySQL database or even NoSQL technologies, such as MongoDB. There are relatively few places to work at that can offer exposure and experience to such environments.

Do you have what it takes to be a “Pythianite”?

Pythian is dedicated to developing their employees, also known as Pythianites. Pythian provides ample opportunity for career growth, but this work is not for everyone. It’s very fast paced and at times stressful. There are high expectations for our consultants, and we genuinely have to love your data.

If you think you  have what it takes to work at Pythian, check out our current opportunities.

Categories: DBA Blogs

Should AUD$ Table Exist on System Tablespace During DB Upgrade?

Pythian Group - Fri, 2014-05-23 07:59

I see this following message on all My Oracle Support notes, which talks about database Oracle manual upgrade steps.

4.16 Verify the existence of the AUD$ tables
Ensure that if the aud$ table exists that it is in the SYS schema and in the SYSTEM tablespace.
If the AUD$ table is not in SYSTEM tablespace and not owned by the SYS user then before doing the upgrade put it back to the SYSTEM tablespace and it should be owned by SYS .

When I come across the same kind of message even for the latest database version 12cR1 on MOS note 1503653.1, I thought of checking the true functionality of this warning. This doubt seems very valid especially when we have new feature named “DBMS_AUDIT_MGMT”, which can be used to relocate and purge data for aud$ table from oracle rdbms version 10gR1.

I created a database named “test” using rdbms version and enabled database auditing. After few sessions testing, I see records on aud$ table. I moved the table and associated LOB segments after disabling db audit and enable it again after the activity completion.

SQL> SELECT comp_id, status, SUBSTR(version,1,10) version, comp_name FROM dba_registry ORDER BY 1;

——- ——– —————————————- ———————————–
CATALOG VALID Oracle Database Catalog Views
CATPROC VALID Oracle Database Packages and Types

SQL> show parameter audit_trail

———————————— ———– ——————————
audit_trail string NONE

SQL> alter table sys.aud$ move tablespace users
2 LOB (sqltext) STORE AS lobsegment1 (TABLESPACE users )
3 LOB (sqlbind) STORE AS lobsegment2 (TABLESPACE users );

Table altered.

SQL> select count(1) from aud$;


SQL> select distinct tablespace_name from dba_segments where segment_name in(‘AUD$’,'SYS_IL0000000384C00040$$’,'SYS_IL0000000384C00041$$’);


SQL> ALTER SYSTEM SET audit_trail=db, extended scope=spfile;

System altered.

SQL> alter system set audit_sys_operations=TRUE scope=spfile;

System altered.

I configured Oracle home of version and executed the pre-upgrade script “preupgrd.sql” on the 11gR2 oracle home. I didn’t notice any error messages related to this table availability on different tablespace. Reviewed the steps required as per MOS note 1503653.1, omitted many points due to the nature of this database including step 4.16. I never faced any issues with the upgrade and even noticed the aud$ table exists on USERS tablespace only after the upgrade.

SQL> SELECT comp_id, status, SUBSTR(version,1,10) version, comp_name FROM dba_registry ORDER BY 1;

——- ——– —————————————- ———————————–
CATALOG VALID Oracle Database Catalog Views
CATPROC VALID Oracle Database Packages and Types
XDB VALID Oracle XML Database

SQL> select owner,count(*) from dba_objects where status=’INVALID’ group by owner;

no rows selected

SQL> select count(1) from sys.aud$;


SQL> select tablespace_name from dba_segments where segment_name=’AUD$’;


SQL> select owner,count(*) from dba_objects where status=’INVALID’ group by owner;

no rows selected

SQL> show parameter compatible

———————————— ———– ——————————
compatible string 12.0.0

SQL> show parameter audit

———————————— ———– ——————————
audit_file_dest string /u02/app/oracle/product/12.1.0/dbhome_1/rdbms/audit
audit_sys_operations boolean TRUE
audit_syslog_level string
audit_trail string DB, EXTENDED

Checked few other MOS notes, it seems they really look for aud$ table existence of SYS schema only.

FAQ : Database Upgrade And Migration (Doc ID 1352987.1)
Which schema should the AUD$ table exist in while doing the upgrade ?
AUD$ table should exist in SYS schema while doing the upgrade.

So this blog question remains valid. For those who keep bigger aud$ table on dedicated tablespace for better database performance, this relaxation means saving 1-3 hours of production database downtime. Is this the time to ask Oracle Support to review the point 4.16 to check for owner only for aud$ table?

Note: This testing was carried out only from rdbms version 11gR2 to 12cR1. Please test this behavior on your test environment before you prepare action plan for the production upgrade.

Categories: DBA Blogs

Log Buffer #372, A Carnival of the Vanities for DBAs

Pythian Group - Fri, 2014-05-23 07:58

Log Buffer Carnival enables readers to see through the minds of database bloggers who are converting their thought process into blog posts. This Log Buffer Edition is the part of same chain. Enjoy.


Tanel Poder is combining Bloom Filter Offloading and Storage Indexes on Exadata.

Randolf talks about 12c Hybrid Hash Distribution with Skew Detection / Handling – Failing.

Kyle talks about 5 Databases issues that are costing you time and money.

Frits Hoogland unfolds as how Exadata Smart Scan works.

A Framework Approach to Building an Oracle WebCenter Intranet, Extranet, or Portal.

SQL Server:

Microsoft adds forecasting capabilities to Power BI for O365

Capping CPU using Resource Governor – The Concurrency Mathematics

Dell Doubles Application Speeds, Processes Transactions 9X Faster with In-Memory OLTP

Architecture of the Microsoft Analytics Platform System

Introducing the AzureCAT PPI Theater at PASS BA


Dean Ellish blogs about using Go with MariaDB.

MySQL 5.6 has added support for EXPLAIN FORMAT=JSON. The basic use case for that feature is that one can look at the JSON output and see more details about the query plan. More advanced/specific use cases are difficult, though.

Real-Time Data Movement: The Key to Enabling Live Analytics With Hadoop.

MySQL Enterprise Monitor 2.3.17 is now available for download on the My Oracle Support (MOS) web site.

If you run multiple MySQL environments on multiple servers it’s a good habit to set your MySQL prompt to double check which server you are on.

Categories: DBA Blogs

Oracle #GoldenGate Replicate Apply (Run) Rate

DBASolved - Thu, 2014-05-22 12:16

For a couple of weeks now, I’ve been trying to figure out a way to identify the size of data for transactions that are getting processed over a give period of time with Oracle GoldenGate.  When I started to think through the process, I keyed in on the Relative Byte Address (RBA).  What is the RBA?  From reading Oracle’s GoldenGate documentation, the RBA is mostly a marker within the trail file to identify the location of the transaction.  This got me to thinking; maybe I can use the RBA to “estimate” the amount of data applied to the source over a period of time (compare 2 RBAs).

Before I ventured off in the unknown; I wanted to verify if there was a method already identified by Oracle.  What I found in MOS was Note ID: 1356524.1.  This note deals mostly with how to identify the speed of the extraction process.  What I found interesting in this note is that Oracle is using the RBA to help calculate the amount of data being extracted.  With this note in hand, I felt comfortable in using the RBA to “estimate” the amount of data being applied by a replicat.

Note:  How to estimate Goldengate extract redo processing speed? (Doc ID 1356524.1)

A few sentences ago, I mentioned that I wanted to compare 2 RBAs to “estimate” the amount of data applied over a period of time.  In order to do this, I need to convert the RBA into meaningful number.

The following formulas I used to convert the RBA to megabytes and then into the metrics I wanted:

(($sec_rba - $first_rba)/(1024*1024))  <-  find the “estimated” size applied in MB
($mb_min*60)                           <- find the “estimate” size applied over an hour in MB
($mb_hr/(1024))                        <- find the “estimate” size applied in GB for an hour
($gb_hr*24)                            <- find the “estimate” size for a day in GB

Now the question was how can I grab this information from each replicat.  The information I needed could be found by doing a “info replicat <replicat>, detail” (The detail part is not really needed, just use it to list out all the associated trail files).    The output from the info command looks similar to this:

Info Replicat Output:


The thing to keep in mind is that I’m only concern about two lines in this output.  The first line is the “Log Read Checkpoint” and the second line that has the Date and RBA number.  Now in order to gather this information and do the calculations using the RBA, I wrote a Perl script.  The  for this basics of the script are below:

#!/usr/bin/perl -w
#Author: Bobby Curtis, Oracle ACE
#Copyright: 2014
use strict;
use warnings;

#Static Variables

my $gghome = "/u01/app/oracle/product/12.1.2/ogg";
my $outfile = "/tmp/gg_replicat_runrates.txt";
my $sleeptime = 60;
my $gguser = "c##ggate";
my $ggpass = "ggate";
my @process = ("replicat");
my $replicat;
my($rate_min, $rate_hr, $rate_gb_hr, $rate_gb_day);


open (RUNRATES, ">>$outfile") or die "Unable to open file";
foreach my $i(@process)
my @process_name = `ps -ef | grep dirprm | grep $i | grep -v grep | awk '{print \$14}'`;   
my @replicats = @process_name;

    foreach (@replicats)
        $replicat = $_;
        check_replicat($gguser, $ggpass, $replicat);
        ($curtrail1,$date1,$rba1) = check_replicat();
        #print "$curtrail1 -> $date1 -> $rba1\n";
        check_replicat($gguser, $ggpass, $replicat);
        ($curtrail2,$date2,$rba2) = check_replicat();
        #print "$curtrail2 -> $date2 -> $rba2\n";
        ($rate_min, $rate_hr, $rate_gb_hr, $rate_gb_day) = calc_rate();
        print RUNRATES "$replicat|$date1|$curtrail1|$rba1|$date2|$curtrail2|$rba2|$rate_min|$rate_hr|$rate_gb_hr|$rate_gb_day\n";
close (RUNRATES);

#Sub Programs

sub check_replicat
my @buf = `$gghome/ggsci << EOF
dblogin userid $gguser\@pdb2 password $ggpass
info replicat $replicat, detail

my $curtrail;
my $date;
my $rba;

    foreach (@buf)
        if (/Log Read Checkpoint/)
            if (m/(\.\/\w+\/\w+)/g)
                $curtrail = $1;
        if (/RBA/)
            if (m/(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2})/g)
                $date = $1."-".$2."-".$3." ".$4.":".$5.":".$6;
            if (m/RBA (\d+)/g)
                $rba = $1;

} #end sub check_replicat

sub calc_rate
    my $first_rba = $rba1;
    my $sec_rba = $rba2;
    my $mb_min = (($sec_rba-$first_rba)/(1024*1024));
    my $mb_hr = ($mb_min*60);
    my $gb_hr = ($mb_hr/(1024));
    my $gb_day = ($gb_hr*24);
    return ($mb_min,$mb_hr,$gb_hr, $gb_day);
} #end sub calc_rate

This script is a bit longer than I like; however, it will capture all information required and then waits 60 seconds and gather the information again for the replicat it is working on. Once the first and second RBA are grabbed then the script writes the output to a flat file with the calculations for MB per min, MB per hour, GB per hour and GB per day.

Once the flat file has been written,  I can now use an external table that will allow me to view this data from SQL (see my other post on monitoring GG from  Using the external table, I can see what my run rates are from any SQL capable tool.  Below is a simple query to pull the data from the external table.

Note: Some numbers in the output may be negative.  This is due to the subtraction between RBA2 (smaller) and RBA1 (larger).

        repgroup as processgroup,
        to_char(date1, 'DD-MON-YY HH:MI:SS') snap1,
        curtrail1 as snap1_trail,
        rba1 as snap1_rba,
        to_char(date1, 'DD-MON-YY HH:MI:SS') snap2,
        curtrail2 as snap2_trail,
        rba2 as snap2_rba,
  repgroup = 'REP';

--Output (unformatted)--

PROCESSG SNAP1              SNAP1_TRAIL                     SNAP1_RBA SNAP2              SNAP2_TRAIL                     SNAP2_RBA RATE_MIN_MB RATE_HR_MB RATE_HR_GB RATE_DAY_GB
-------- ------------------ ------------------------------ ---------- ------------------ ------------------------------ ---------- ----------- ---------- ---------- -----------
REP      22-MAY-14 01:38:51 ./dirdat/rt000034                 2905346 22-MAY-14 01:38:51 ./dirdat/rt000034                 3197702         286      17130         17         401
REP      22-MAY-14 01:39:49 ./dirdat/rt000034                 3197702 22-MAY-14 01:39:49 ./dirdat/rt000034                 3521610         316      18979         19         445
REP      22-MAY-14 01:40:50 ./dirdat/rt000034                 3521610 22-MAY-14 01:40:50 ./dirdat/rt000034                 3802260         274      16444         16         385
REP      22-MAY-14 01:41:49 ./dirdat/rt000034                 3802260 22-MAY-14 01:41:49 ./dirdat/rt000034                 4112529         303      18180         18         426
REP      22-MAY-14 01:42:49 ./dirdat/rt000034                 4112529 22-MAY-14 01:42:49 ./dirdat/rt000034                 4463477         343      20563         20         482


Being able to use an external table to view run rates additional scripts can be written to report on what is going on within the Oracle GoldenGate apply process.  Allowing administrators a better understanding of what is going on within their environments.  At the same time, I think this information is valuable in the turning process of Oracle GoldenGate as environment grown.

Let me know your thoughts and comments on this, because it is always interesting to see how other organizations solve these issues as well.


twitter: @dbasolved


Filed under: Golden Gate
Categories: DBA Blogs

Standalone 12c grid install example

Bobby Durrett's DBA Blog - Wed, 2014-05-21 14:33

Here are my rough screenshots from an install of 12c grid on a standalone Linux vm: pdf

I’m running version 6 of Oracle’s Linux in a VMWare Player 4 gigabyte virtual machine on my Windows 7 laptop.  I ran into a couple of key points that I wanted to document.


I added two new disks to my VM but after booting my machine they disappeared.  I ended up adding them back in and rebooting again and they stayed.  Not sure what to say except after you add them reboot and make sure they are still there.


The new disk devices showed up as /dev/sdb and /dev/sdc.  Then I had to run fdisk on each one to create a partition that took up the entire disk.  That led to devices being out there called /dev/sdb1 and /dev/sdc1.

Next I had to do some steps related to the oracleasm utility but I found out later that the next step I should have done was disable SE Linux:


I had to edit the file /etc/selinux/config so that SELINUX=disabled and reboot.  Then I ran these commands to configure oracleasm:

yum install oracleasm-support
/usr/sbin/oracleasm configure -i
/usr/sbin/oracleasm init
/usr/sbin/oracleasm createdisk DISK1 /dev/sdb1
/usr/sbin/oracleasm createdisk DISK2 /dev/sdc1

The next tricky thing was figuring out the path to these two disks during the creation of the disk group as part of the grid install.  Here is what the install screen looked like:


It didn’t have any disks to choose from.  I tried various discovery paths such as /dev/sd* and ORCL:* but finally found one that worked:


Now the disks showed up and I was able to continue:


So, that’s all I wanted to point out, just a few key things I had to understand.  You can check out my link for all the screenshots I took.

- Bobby

Categories: DBA Blogs

Microsoft Analytics Platform System: Name Overhaul in Big Data War!

Pythian Group - Wed, 2014-05-21 08:18

I had the chance to attend a course about what used to be called Parallel Data Warehouse (PDW). PDW was introduced few years ago with the offering of SQL Server 2008 R2 Parallel Data Warehouse , something very few people could get their hands on. The appliance used to cost a ton of money, too many parts and only offered by HP or DELL in a pre-configured setup.

With SQL server 2012, Microsoft made many enhancements slashing the size of the appliance to almost half, and consequently the cost, and improving the performance as well.

Just while I was attending the course, Microsoft announced a name change and the introduction of new fancy brand name: Microsoft Analytics platform. CEO Satya Nadella announced the new platform with other products as well. I suggest reading this blog written by Satya himself

I’m sharing some of my personal (again, personal) opinions here about the platform and the appliance. So let’s take a step back and explore some of the basics here.

What is PDW (aka APS)?

Microsoft loves those three letters acronyms, although certifications may be an exception. Not to go to great lengths, it’s a Massively parallel Processing (MPP) “APPLIANCE” that is optimized for large scale enterprise data warehouses. The appliance is a logical entity that encompasses servers , switches , storage enclosed into a rack. Think of it as your typical environment of servers, switches and storage all brought together in one huge rack appliance. The idea behind the appliance is simple: We do all the dirty work for you and give you something “optimized” to handle huge amounts of data without the hassle of configuration, tuning and license worries; Of course the word “optimized” is according to Microsoft terms.


The appliance is not only about SQL server but it also incorporates Hadoop and an engine, PolyBase, to simplify talking to Hadoop using conventional SQL server T-SQL and can also tap HDsinghts to reach out to data stored in the cloud.

The appliance is only available through few vendors, used to be only HP and DELL but now also includes Quantas. Please check resources section for more information about Microsoft Analytics Platform.

The following video vividly tries to demonstrate the usage of APS:
Why PDW/APS appliance ?

Customers with huge amounts of data that also spans heterogeneous sources want always to get meaningful information out of that data. The more the data they have , the harder and longer the time to extract key information. Appliances are tuned machines with massive resources to help analyze , aggregate and join data much faster. Conventional SMP machines can work up to a certain level with much needed tuning and optimization that may not always work. vendors take this tuning and optimizations responsibility and present you a sleek machine that is supposed to overcome multiple design and resources limitations. Some of the examples of existing appliances are Oracle Exadata , Teradata Data Warehouse Appliance and IBM PureData and Netezza.

Are you saying that conventional SQL server setup can’t achieve this? Not entirely. Think of this as car upgrades where they may be based on the same chassis but high-end models have more powerful engines, features and performance. Although SQL server keeps bringing enhancements like updatable clustered columnstore indexes and in-memory OLTP in SQL server 2014 , PDW/APS appliance differs from conventional SMP in the following areas:

  1. PDW/APS appliance is a bundle of hardware and software offering customized to scale out. You can add and remove(much harder though) nodes to scale out to your data needs.Each “node” runs on separate server with seperate SQL server and hardware resources and managed by a “control” node to distribute the workload. You can read about APS Solution Brief here
  2. You can’t buy a PDW SQL server licence and install in your environment and you can not even assemble the product even if you have the blueprint , you just get it from one of the vendors and plug-n-play it.
  3. PolyBase plugs in Hadoop. You may be able to connect existing SQL server with Hadoop but Polycase provides easy to use T-SQL functions to extract data from Hadoop providing almost immediate ability to query Hadoop without a long learning curve.
  4. Many conventional SQL server features are suppressed. Yes , I can see your raised eyebrows but the idea is that Microsoft wanted to remove areas that can introduce bottlenecks such as CLR , Extended dlls and even SQL server agent. If you need to do something that can’t be done inside PDW , such as scheduled jobs, then move it to another tier.

Where does PDW/APS fit?

The cost of buying and running the appliance suggests that it’s not for everyone. The available resources and bundling Ploycase to connect to Hadoop shows that it’s for an enterprise with huge and heterogeneous amounts of data that is spread around. Bringing this data together with least customization is the goal of the appliance.

PDW/APS can help bring data together from following areas:

  • Social apps
  • Mobile
  • Sensors
  • Web
  • Other data sources such as RDBMS

The appliance fits a segment of industries, notably:

  • Retail
  • Healthcare
  • Financials
  • Manufacturing
  • Social media

Microsoft has some case studies about clients deploying PDW and realizing up to 100X performance gain. Here are the case studies:

  1. MEC -Media Firm Uncovers the Value of Digital Media with Parallel Data Warehouse
  2. The Royal Bank of Scotland – Leading UK Bank Gains Rapid Insight into Economic Trends with Analytics Platform System
  3. Progressive Insurance – Progressive Data Performance Grows by Factor of Four, Fueling Business Growth Online Experience

I believe Microsoft has to do more to get the appliance to more customers and I think the brand rename is part of this push. Training, support and deployment materials are also needed since there is not much resources online.
Is PDW worth it for clients?

Microsoft competes against TeraData, Netezza and Oracle Exadata. Cost is a very big factor: Licence and support. MS tends to do fairly well with MS shop customers and SQL server base clients. However, first version of PDW tended to be so expensive and bulky but current appliance is almost half price and half size than used to be. Expertise seems to be low still and this is what MS is working on.

Microsoft word is that instead of investing too much and too long on creating the same technology by trial and error and spend much time on tuning , here’s a working appliance that we have tuned it for you and just focus on your business. Per following chart, MS claims the cheapest price per TB compared to other vendors.


Regardless , the appliance makes more sense to SQL server clients even more ; however , I still see clients sticking to solutions from vendors of the main RDBMS technology they run since importing data will easier and learning curve will be less steep.

The appliance will make a case for mid to large enterprises with new Terabytes of data each month including unstructured data. SMP SQL and APS may correlate in the region of few to tens of terabytes but once we talk about hundreds of terabytes of data including unstructured data then APS starts to make sense.
PDW Against Cloud?

There are few reasons clients may opt for an in-premise appliance, including :

  1. Some data is sensitive to trust putting in the cloud.
  2. The amount of data is huge to upload to cloud.
  3. Cloud is not mature yet to support all features.

Most cloud vendors are not yet ready to offer such expensive appliance. Amazon, however, has something similar called Redshift. They actually make a case against on-premise solution saying you don’t need those bulky expensive appliances that can break, while you can use Amazon cloud solution and pay “less”. However, there are few points :

  1. MS appliance tries to play in the lower segment of cost.
  2. You don’t need lots of DBAs to manage. In fact, I was surprised that MS took out most of the the parts that can introduce problems with the appliance : no CLR, no extended modules, many other features were disabled. They applied best-practices and locked it so you can not temper with the appliance. I was told that the only thing that can cause APS to fail is a hardware failure and we already have redundancy so a failure is even less probable
  3. Not everyone wants their data in cloud , mostly for security. I was told about a customer who wanted to destroy , with a hammer, the hard drives after testing the appliance. It took few weeks to zero write the drives , few times.
  4. Transferring a lot of data to public cloud is not that fast , unless you are already hosting your data in same location such as on Amazon.

APS VS Hadoop

Hadoop excels in non-structred data such as text , sensors data , web crawling ..etc and whether you already have existing Hadoop lusters running or plan to , you may still have valuable relational data stored in your existing SQL server instances. APS makes it easy to bridge the gap between the two and use T-SQL to join the data from the two sources without worrying much about the design of Hadoop cluster.

APS region share

USA is top then EU then Asia.
APS and SQL 2014

The appliance still runs a customized version of SQL server 2012 , no word yet when SQL 2014 will be introduced. Upgrading the cluster is supported but it is not something end-customer can do yet.
PDW support

Many cases are still only supported by Microsoft Customer service and support (CSS) like failing back and downsizing but they are trying to automate some tasks to be done by experienced DBAs.
DBA role with APS

Don’t hold your breath! As outlined before, much of the configuration and optimizations are done for you in what MS believes is the best balance. You can not do many of the tasks a DBA does like changing Tempdb configurations, max degree of parallelism, etc. That’s the idea behind the appliance in fact. Focusing on bringing the data to the appliance and modifying your design to extract information.

When I did work with the appliance , I didn’t find it particularly complex from an operations point of view. Most of the work is about bringing data in, figuring out the best way to join data together without shuffling data around and that’s about understanding the data and business logic.

You can help in the following areas though:

  • Exporting> importing data from existing data sources into APS
  • Advise any changes to the design and business logic to comply with appliance requirements
  • Advise how to bring data together for analysis.
  • Design and implement data extraction practices.
  • Troubleshoot analysis routines and schedules.
  • Troubleshoot long running queries and schedules. APS has a web portal where you can see all running processes; you can also use DMVs to get this information and some of them are unique to APS.


APS appliance targets customers with huge amount of data that span heterogeneous sources who need read to plug solution.

With the new brand of the PDW appliance, Microsoft is getting more serious about big data and analytics. However, many vendors are well-established here and it’s still a long run in a market that’s expected to explode if it has not started yet.

Happy reading!

Categories: DBA Blogs