Author - Corrado Pandiani

Column Histograms on Percona Server and MySQL 8.0

MySQL Column HIstorgrams

From time to time you may have experienced that MySQL was not able to find the best execution plan for a query. You felt the query should have been faster. You felt that something didn’t work, but you didn’t realize exactly what.
Maybe some of you did tests and discovered there was a better execution […]

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MongoDB: Impact-free Index Builds using Detached ReplicaSet Nodes

MongoDB Impact-free Index Builds

Creating an index on a MongoDB collection is simple; just run the command CreateIndex and that’s all there is to it. There are several index types available, and in a previous post, you can find the more important index types: MongoDB index types and explain().
The command is quite simple, but for MongoDB, building an […]

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MySQL: Disk Space Exhaustion for Implicit Temporary Tables

Implicit Temporary Tables

I was recently faced with a real issue about completely exhausting the disk space on MySQL. This was a serious issue because of the continuous outages of the service, as the customer had to constantly restart the server and wait for the next outage.
What was happening? In this article, I’m going to explain it […]

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Solve Query Failures Regarding ONLY_FULL_GROUP_BY SQL Mode

Solve Query Failures SQL mode

“Hey, what’s going on with my applications? I installed a newer version of MySQL. I have queries that perfectly run with the older version and now I have a lot of errors.”
This is a question some customers have asked me after upgrading MySQL. In this article, we’ll see what one of the most frequent […]

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Using Partial and Sparse Indexes in MongoDB

MongoDb using partial sparse indexes

In this article I’m going to talk about partial and sparse indexes in MongoDB® and Percona Server for MongoDB®. I’ll show you how to use them, and look at cases where they can be helpful. Prior to discussing these indexes in MongoDB in detail, though, let’s talk about an issue on a relational database like […]

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