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Oracle Team

Linux: how to monitor the nofile limit

By | Operation systems, Oracle | One Comment

By Franck Pachot . In a previous post I explained how to measure the number of processes that are generated when a fork() or clone() call checks the nproc limit. There is another limit in /etc/limits.conf – or in /etc/limits.d – that is displayed by ‘ulimit -n’. It’s the number of open files – ‘nofile’ – and here again we need to know what kind of files are counted. nofile ‘nofile’ is another limit that…

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Stéphane Haby

SQL Server: How to find the default data path?

By | Database management | 4 Comments

I have read a lot of SQL Server blog postings and articles in order to find the default data path. This post covers different SQL Server versions (SQL Server 2012, SQL Server 2014, SQL Server 2008, SQL Server 2005) and provides a generic script with different methods. Search with SERVERPROPERTY Since SQL Server 2012, we can use the parameter “InstanceDefaultDataPath” in the T-SQL command SERVERPROPERTY. More information on msdn here. Test with SQL server 2008…

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David Barbarin

SQL Server 2014: sys.dm_exec_query_profiles, a new promising feature

By | Application integration & Middleware | 3 Comments

Among the hidden features provided by SQL Server 2014 there is a very interesting dynamic management view named sys.dm_exec_query_profiles. This feature will help the database administrators and experienced developers to troubleshoot long running queries in real-time. I’m pretty sure you had to deal with the following questions: When will this query finish? What percentage of total workload is performed by this request? Which steps are the longest? Before SQL Server 2014 it was impossible to…

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Oracle Team

Linux: how to monitor the nproc limit

By | Database Administration & Monitoring, Oracle | 16 Comments

By Franck Pachot . You probably know about ‘nproc’ limits in Linux which are set in /etc/limits.conf and checked with ‘ulimit -u’. But do you know how to handle the monitoring and be alerted when you’re close the fixed limit? Nproc and ps Nproc is defined at OS level to limit the number of processes per user. Oracle 11.2.0.4 documentation recommends the following: oracle soft nproc 2047 oracle hard nproc 16384 But that is often…

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David Barbarin

SQL Server 2014: Availability groups failover impossible with Failover Cluster Manager

By | Hardware & Storage | 2 Comments

A couple of weeks ago, I worked for a customer that wanted to implement SQL Server 2012 (and not SQL Server 214) AlwaysOn with availability groups. During our tests we performed a bunch of failover tests and the customer tried to perform a failover of one of the installed availability group by using the failover cluster manager (FCM). Of course, I told him this is not best practice because the failover cluster manager is not…

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Oracle Team

How to list all Oracle system schemas

By | Database management, Oracle | 4 Comments

By Franck Pachot . Do you want to know which users come with the Oracle Database and which are the ones you have created? This is that not easy, especially prior to Oracle 12c. You know SYS and SYSTEM, but there are many others – especially when you have installed all options. And it is important to know them all, e. g. when you import or apply a password policy, etc. Let’s see the options…

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Stéphane Savorgnano

How to avoid Failover Cluster with PowerShell scripting

By | Application integration & Middleware | No Comments

One of my colleague asked me some days ago if I could create a PowerShell script to get rid from Windows Server Failover Cluster. The reason is that it has, in some specific cases, the bad habit to failover a resource or a service even when we don’t want it. To be honest, I use a lot the Failover Cluster feature of Windows Server without any problems as a SQL Server DBA, but for this specific…

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Morgan Patou

Configure a Kerberos Client and Alfresco as a Kerberized application

By | Application integration & Middleware | No Comments

In the previous blog, I described How to install and manage a Kerberos Server but that’s useless if there are no clients and if no application have been kerberized! That’s why in this blog I will explain in the first part how to install a kerberos client in linux. The second part will be dedicated to the configuration of a browser to use Kerberos tickets and the last part will explain how to configure a…

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Oracle Team

Oracle Exadata – poor optimization for FIRST_ROWS

By | Database Administration & Monitoring, Oracle | 3 Comments

By Franck Pachot . In a previous blog, I discussed the difference between rownum and row_number(), in particular their behaviour in implicitely adding a first_rows(n) to the optimizer. That reminded me that I forgot to blog about an issue I encountered and which concerns both approaches. It was on an Exadata: a nice full table scan with smartscan was taking a long time. And forcing to an index access – with a very bad index…

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David Barbarin

Tempdb enhancements with SQL Server 2014

By | Application integration & Middleware | No Comments

SQL Server 2014 is definitively designed for performance and I will try to demonstrate it during this blog post. I like to talk about hidden performance features because generally it does not require any changes for applications unlike in-memory tables for instance (aka hekaton tables). Since SQL Server 2005 version some improvements have been made for tempdb. Tempdb caching is one of them and allows to reduce the page allocation contention. Basically to create a…

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Oracle Team

Oracle 12c extended datatypes better than CLOB?

By | Database management, Oracle | 6 Comments

By Franck Pachot . 12c has introduced character strings that can can go above 4000 bytes. In the previous versions, in PL/SQL only we were allowed to have VARCHAR2 up to 32k. In SQL the VARCHAR2 datatype was limited to 4000 and CHAR was limited to 2000. That became a bit small especially when lot of applications needed to store unicode characters. From 12c we can have SQL datatypes having up to 32k bytes for…

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