Performance

CPUs: Cores versus Threads on an Oracle Server

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(…)

Index seek operator and residual IO

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(…)

Experiencing update statistics on a big table with circuitous ways

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(…)

SQL Server 2016: distributed availability groups and cascaded replicas

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 AlwaysOn availability groups and statistic issues on secondaries

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(…)

Partitioning – When data movement is not performed as expected

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(…)

When an index seek operator is not always your friend

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(…)

SQL Server AlwaysOn: troubleshooting improvements with new service packs

As promised in my latest blog, I will talk about improvements in the detection of the availability group replication latency. As a reminder, replication latency between high(…)

SQL Server 2016 AlwaysOn: Direct seeding and performance considerations

This blog post follows the previous one about new direct seeding feature shipped with SQL Server 2016. As a reminder, I had some doubts about using direct seeding with large databases because log stream is not(…)

A look at PostgreSQL 9.6 – The wait interface

For a long time there was no real wait interface in PostgreSQL core. Now, with the upcoming 9.6, pg_stat_activity was extended to provide more meaningful information for what a session is currently waiting on.