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Oracle Team

Lighty for PostgreSQL

By | Database Administration & Monitoring, Postgres | No Comments

By Franck Pachot . If you follow this blog, you should know how I like Orachrome Lighty for Oracle, for its efficiency to monitor database performance statistics. Today Orachrome released the beta version of Lighty for Postgres: https://orachrome.com/news/la-beta-de-lighty-for-postgresql-est-ouverte/ The Cloud is perfect to do short tests with more resources than my laptop, especially the predictability of performance, then I started a Bitnami Postgres Compute service on the Oracle Cloud and did some tests with pgbench…

 
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Stéphane Haby

SQL Server 2017: Can I run a “standard” rebuild on the index after a Resumable Online Index Rebuild is suspended?

By | Database Administration & Monitoring, Development & Performance, SQL Server, Technology Survey | No Comments

This article is an additional article to my precedent about “SQL Server 2017: What’s happens with an interruption during a Resumable Online Index Rebuild?” The goal is to see after I suspend the rebuild, if I can run a traditional rebuild without the option RESUME.   I start an index rebuild with the option Resumable: ALTER INDEX [NCI_dbo_Transaction] ON [dbo].[Transaction] REBUILD WITH (RESUMABLE = ON, ONLINE = ON) GO   In a new query window,…

 
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Stéphane Haby

SQL Server 2017: What’s happens with an interruption during a Resumable Online Index Rebuild?

By | Database Administration & Monitoring, Development & Performance, SQL Server, Technology Survey | No Comments

Last week, I presented this option in our internal event, the dbi xChange. My colleague David Barbarin asked me this question, what’s append if an interruption occurs (reboot, SQL Server service stopped,…) during a Resumable Online Index Rebuild? I was not able to answer because I forgot to do this test. The new enhancement for an index rebuild provides the capability to suspend, resume or abort an online index operation (msdn reference). I always use…

 
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Clemens Bleile

CPUs: Cores versus Threads on an Oracle Server

By | Database Administration & Monitoring, Database management | 2 Comments

When doing a performance review I often do talk with the DBA about the CPU utilization of the server. How reliable is the server CPU utilization with tools like top or the host CPU utilization in the AWR-report? E.g. on an Linux Intel x86-64 server with 8 Cores and 16 logical CPUs (Intel Hyperthreading), what does a utilization of 50% mean? As I had an ODA X7-M in a test lab available, I thought I’ll…

 
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David Barbarin

Index seek operator and residual IO

By | Database Administration & Monitoring | No Comments

This blog post draws on the previous article about index seek and gotchas. I encountered another interesting case but it is not so much because of the nature of the problem I decided to write this article but rather the different ways that exist to troubleshoot it. Firstly, let’s set the scene: A simple update query and its corresponding execution plan that tend to say the plan is efficient  in terms of performance declare @P0…

 
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David Barbarin

Experiencing update statistics on a big table with circuitous ways

By | Database Administration & Monitoring | No Comments

This is my first blog of this new year and since a while by the way. Indeed, last year, I put all my energy to realign my Linux skills with the new Microsoft’s strategy that opens SQL Server to Open Source world. But at the same time, I did a lot of interesting stuff at customers shops and I decided to write about one  of them to begin this new year 2018. In this blog…

 
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David Barbarin

SQL Server 2016: distributed availability groups and cascaded replicas

By | Database Administration & Monitoring | No Comments

During the last MVP summit, we had some interesting discussions about availability groups with the SQL Server team and I remember someone asked for managing scenarios like Oracle cascaded destinations and the good news is that SQL Server 2016 already addresses this kind of scenario with distributed availability groups. For example, let’s say you have to manage heavily reporting activity on your application and a solution would be to offload this activity across several secondary…

 
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David Barbarin

SQL Server AlwaysOn availability groups and statistic issues on secondaries

By | Database Administration & Monitoring | 9 Comments

I would like to share with you an interesting issue you may face while using SQL Server AlwaysOn availability groups and secondary read-only replicas. For those who use secondary read-only replicas as reporting servers, keep reading this blog post because it is about update statistics behavior on the secondary replicas and as you may know cardinality estimation accuracy is an important part of the queries performance in this case. So a couple of days ago,…

 
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David Barbarin

Partitioning – When data movement is not performed as expected

By | Database Administration & Monitoring | No Comments

This blog is about an interesting partitioning story and curious data movements during merge operation. I was at my one of my customer uses intensively partitioning for various reasons including archiving and manageability. A couple of days ago, we decided to test the new fresh developed script, which will carry out the automatic archiving stuff against the concerned database in quality environment. Let’s describe a little bit the context. We used a range-based data distribution…

 
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David Barbarin

When an index seek operator is not always your friend

By | Development & Performance | No Comments

Did you ever consider an index seek as an issue? . Well, let’s talk about a story with one of my customers where the context is pretty simple: a particular query that is out of the range of the application’s performance requirements (roughly 200ms of execution time in average). The execution plan of the query was similar to what you may see in the picture below:   At first glance, no obvious way to improve…

 
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