Memory-Mapped Persistence But let me start at the beginning, MongoDB’s persistence cycle, and then get to what’s being done to improve its reliability and your data’s durability. At the very heart, MongoDB uses memory-mapped files to store data. A memory-mapped…
Write-Ahead Logging (WAL) Write-Ahead Logging (WAL) is a standard method for ensuring data integrity. A detailed description can be found in most (if not all) books about transaction processing. Briefly, WAL‘s central concept is that changes to data files (where…
Why would anyone want to use PostgreSQL instead of SQL Server? There are a lot of factors to consider when choosing how to store your data. Sometimes we need to look deeper than the standard choice and consider something new….
Oracle vs Postgres vs SQLServer vs MySQL vs IBM-DB2 vs Firebird vs H2 HSQLDB vs Derby vs SQLite This comparison focuses on features that can be used in SQL statements or self-contained SQL scripts that don’t require additional software (e.g….
Dynamic columns came to my attention a few days back. Since then I read a little bit more in the documentation (see Dynamic columns in the Knowledge Base) and played with it a little. The reason I became curious was…
The first questions I would ask when interviewing a potential DBA would be one that would help me find out about his/her skills and in particular if they are aware of MySQL specific idiosyncrasies. Instead of asking about specific query,…
Replication has been one of the most popular MySQL features since it made its way into the application more than a decade ago. However, as replication implementations became more complex over time, some limitations of MySQL’s original replication mechanisms started…
The Basics The topology uses 3 servers: A is the active master, B a stand-by master set up to replicate from A and C a multi purpose slave replicating from A. I also set up A to replicate from…
Installing MariaDB became very easy on the latest CentOS /RHEL Linux version 7. During initial setup MariaDB has a tick in the graphical setup environment which enables MariaDB and replaces MySQL. During installation the section allows enabling a MariaDB server….
You’ve lost the root password for your MariaDB database – now what do you do? You can’t recover your existing password, but you can get into your database to create a new root password. You just need root privileges on…