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Join transitive closure and query simplification considerations
Yesterday, I had a discussion with one of my friend who works with Oracle about some different behaviours between each query optimizer against one particular query. You can read his blog post and get...
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SQL Server AlwaysOn: number of databases and the hadr worker pool
Often, when I’m in charge to implement an SQL Server AlwaysOn infrastructure with availability groups, customers ask me if it exists some best practices and recommendations about the maximum number of...
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Want to benchmark your storage? It’s time to switch to DiskSpd tool!
As you certainly know, the well-known tool SQLIO is officially deprecated since few months. From my part, I had the opportunity (maybe the last) to use SQLIO for a customer project in order to...
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SSISDB is too big and it is not every time the retention period’s fault!
In all blogs that I read, the solution is just to change the retention period to a reasonable value. Yes, it is true but in some case you need to go deeper in the analysis… Like you, I changed the...
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SQL Server 2016 query store
One of the most new interesting features that will be introduced by SQL Server 2016 is certainly the query store that will complete the performance tuning toolbox of database administrators. Basically,...
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SQL Server 2016 : availability groups and performance improvements
During the last SQL Saturday in Paris, I had the opportunity to co-present the new SQL Server 2016 features and one of my topic concerned the availability group’s enhancements. I mentioned the...
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SQL Server Collation for System Center Products
A customer asks me, what is the collation for System Center products? Do we have a general collation for all products? And what is the BP for Tempdb? And how work the licencing for SQL Server in System...
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SQL Server Extended Event: Eine Deadlock-Event aus der...
Wie Sie vielleicht wissen, gibt es eine Überwachung über Extended Events: system_health. Kürzlich fragt mich ein Kunde an, um ein zufälliges Deadlock-Problem zu analysieren… Ich hatte im September in...
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SQL Server AlwaysOn and availability groups : session timeout parameter
Have you ever faced to timeout issues with SQL Server availability groups? If you take a look at the timeout parameters for an availability group, you will find a plenty of configuration settings....
View ArticleEnable 10046 Tracing for a specific SQL
Available methods to enable 10046 trace are described in My Oracle Support Note 376442.1. You can enable 10046-tracing – on session level (alter session) – for other sessions (e.g. with oradebug, the...
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NOLOCK is definitely not what you may expect …
For those who still believe that using nolock hint is a lock-free process, keep reading this blog post. I wrote a previous blog post 3 years ago, when I was at one of my customer and we had an...
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Changing an existing partition configuration … Well, not so easy!
This time let’s talk about an interesting customer scenario where table partitioning was implemented on a table with 100 GB of data on SQL Server 2014. Partitioning in this context aimed to save disk...
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Sudden drop of the page life expectandy but don’t panic yet!
A couple of weeks ago, I had an interesting discussion with one of my customer about the page life expectancy (aka PLE). He asked me if monitoring the metric value is a best practice because he often...
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SQL Server 2016 : nonclustered columnstore index and aggregate pushdown
Did you miss aggregate pushdown capability shipped with columnstore index? Well, I remember the first time I heard about it is was when I read the very interesting blog post of Niko Neugebauer here...
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SQL Server 2016: new database-scoped configuration parameters part 2
In this blog post, let’s continue with other database-scoped options shipped with the SQL Server 2016 RC0. We will first begin with the first one and my preferred option: setting the MAXDOP value for...
View ArticleA 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...
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SQLSaturday #510–Locks, latches et spinlocks
J-16 avant le prochain SQL Saturday à Paris et il est encore temps de s’inscrire. Le prochain SQL Saturday en quelques chiffres c’est: 4 parcours 20 sessions + Chalk-Talk 9 nationalités 15 speakers...
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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...
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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 available replicas may be...
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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...
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