Replication

PostgreSQL Streaming Physical Replication With Slots

postgres replication using slots

PostgreSQL streaming physical replication with slots simplifies setup and maintenance procedures. Usually, you should estimate disk usage for the Write Ahead Log (WAL) and provide appropriate limitation to the number of segments and setup of the WAL archive procedure. In this article, you will see how to use replication with slots and understand what problems […]

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MySQL High Availability: Stale Reads and How to Fix Them

solutions for MySQL Stale Reads

Continuing on the series of blog posts about MySQL High Availability, today we will talk about stale reads and how to overcome this issue.
The Problem
Stale reads is a read operation that fetches an incorrect value from a source that has not synchronized an update operation to the value (source Wiktionary).
A practical scenario is when […]

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Caveats With pt-table-checksum Using Row-Based Replication, and Replication Filters

pt-table-checksum row based replication caveat

As per the documentation, pt-table-checksum is a tool to perform online replication consistency checks by executing checksum queries on the master, which produces different results on replicas that are inconsistent with the master.
The master and each slave insert checksums into the percona.checksums table, and these are later compared for differences. It’s fairly obvious that […]

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How to Quickly Add a Node to an InnoDB Cluster or Group Replication

Quickly Add a Node in InnoDB Cluster or Group Replication

Quickly Add a Node to an InnoDB Cluster or Group Replication (Shutterstock)
In this blog, we’ll look at how to quickly add a node to an InnoDB Cluster or Group Replication using Percona XtraBackup.
Adding nodes to a Group Replication cluster can be easy (documented here), but it only works if the existing nodes have retained […]

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MongoDB Replica set Scenarios and Internals

MongoDB replica sets replication internals r

The MongoDB® replica set is a group of nodes with one set as the primary node, and all other nodes set as secondary nodes. Only the primary node accepts “write” operations, while other nodes can only serve “read” operations according to the read preferences defined. In this blog post, we’ll focus on some MongoDB replica set scenarios, […]

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Setting up Streaming Replication in PostgreSQL

postgres streaming replication

Configuring replication between two databases is considered to be a best strategy towards achieving high availability during disasters and provides fault tolerance against unexpected failures. PostgreSQL satisfies this requirement through streaming replication. We shall talk about another option called logical replication and logical decoding in our future blog post.
Streaming replication works on log shipping. […]

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Replication from Percona Server for MySQL to PostgreSQL using pg_chameleon

postgres mysql replication using pg_chameleon

Replication is one of the well-known features that allows us to build an identical copy of a database. It is supported in almost every RDBMS. The advantages of replication may be huge, especially HA (High Availability) and load balancing. But what if we need to build replication between 2 heterogeneous databases like MySQL and […]

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