(Nilnandan Joshi) Recently, I have worked on one of this case where customer wanted to convert master-slave to master-master replication. They wanted to write on one master and keep another master as a hotspare. Many people are using this kind of environment with MySQL replication.

(Hans-Juergen Schoenig) To use PostgreSQL replication it is necessary to change the wal_level from “minimal” to “hot_standby”. But, which impact does this change have on the amount of WAL actually written to disk? And which impacts does it have in performance? Many people have been asking this quest

(Jeremy Smyth) If you create a table using a numeric type like INT or BIGINT, you might have been surprised by the numbers that appear in the table’s DESCRIBE:

(Andrew Morgan) MySQL Fabric is a new framework that adds High Availability (HA) and/or scaling-out for MySQL. This is the second in a series of posts on the new MySQL Fabric framework; the first article (MySQL Fabric – adding High Availability to MySQL) explained how MySQL Fabric can deliver HA and

(Leo Hsu and Regina Obe) In this exercise, we’ll go thru installing PostgreSQL 9.3 on a CentOS 6 64-bit box. We’ll cover upgrading in a later article. For the rest of this article, we’ll go over configuring yum to use the PostgreSQL PGDG Yum repository found at http://yum.postgresql.org , which has

(Mark Callaghan) Both MongoDB and InnoDB support ACID. For MongoDB this is limited to single document changes while InnoDB extends that to multi-statement and possibly long-lived transactions. My goal in this post is to explain how the MongoDB journal is implemented and used to support ACID. Hopeful

(Marco Tusa) The more I have to interact with customers asking about MySQL/Galera, the most I have to answer over and over to the same question about what kind of network conditions Galera can manage efficiently.

(Michael Paquier) A new feature is showing up in PostgreSQL 9.4 allowing to get more information about transaction lock waits and their circumstances. It has been introduced by this commit:

(Nilnandan Joshi) Working as a Percona Support Engineer, every day we are seeing lots of issues related to MySQL replication. One very common issue is slave lagging. There are many reasons for slave lag but one common reason is that queries are taking more time on slave then master.

(Arnaud Adant) This question was asked at support by a customer to solve a difficult issue.