Tag: replication

Feed: Planet PostgreSQL. In the upcoming release of PostgreSQL-14, we will see multiple enhancements in Logical Replication which I hope will further increase its usage. This blog is primarily to summarize and briefly explain all the enhancements in Logical Replication.Decoding of large transactions:Allow streaming large in-progress transactions to subscribers. Before PostgreSQL-14, the transactions were streamed only at commit time which leads to a large apply lag for large transactions. With this feature, we will see apply lag to be reduced, and in certain scenarios that will lead to a big performance win. I have explained this feature in detail in ... Read More

Feed: Planet PostgreSQL. A fundamental part of the Logical Replication PUBLISHER/ SUBSCRIBER model design is how background worker processes are used to implement a subscription. This blog gives some background about the subscription worker processes and summarises some of the enhancements that we have made to the Tablesync Worker.Much of what we have been doing in this area is not user-facing; it is necessary to give some background information so that our changes can be described in context. Workers SUBSCRIPTION replication is performed by two kinds of background workers: An Apply Worker One or more Tablesync Workers. The CREATE SUBSCRIPTION command ... Read More

Feed: Planet MySQL; Author: Kedar Vaijanapurkar; Two or more dots in your relay log or binary log names can break replication; but worry not, it will only do it once. If you request to start again, it will work. That’s it, that’s the blog. Should you choose to spend some more time, go ahead. A new MySQL 5.7 GTID replication chain was being constructed and fail-overs were being tested while an oddity of MySQL replication revealed itself. The Orchestrator graceful fail-over was not able to attach the replica and reporting an error. Last_SQL_Error: Relay log read failure: Could not parse ... Read More

Feed: Planet PostgreSQL. Even if logical replication is a method of major upgrade itself, sometimes you’ll want to mix and match them. Consider the following scenario: a big and busy database that has a logical replica, which has its specific tables and indexes. When it’s time to upgrade, you will probably want to upgrade both instances – the publisher and the subscriber. As the database is big an busy, using logical replication itself or dump-and-restore aren’t the best choices – those methods will require massive amount of storage, and dump-and-restore will also require a long period of downtime. So, the ... Read More

Feed: Planet PostgreSQL. Logical Replication was introduced in PostgreSQL-10 and since then it is being improved with each version. Logical Replication is a method to replicate the data selectively unlike physical replication where the data of the entire cluster is copied. This can be used to build a multi-master or bi-directional replication solution. One of the main differences as compared with physical replication was that it allows replicating the transaction only at commit time. This leads to apply lag for large transactions where we need to wait to transfer the data till the transaction is finished. In the upcoming PostgreSQL-14 ... Read More

Feed: Planet MySQL; Author: Continuent; In our two most recent posts on MySQL replication we looked at how to securely replicate from MySQL to Amazon Redshift and Amazon Aurora (and vice versa); and here we look at replication between any native MySQL or MariaDB and Amazon RDS (Relational Database Service).  Why Replicate From MySQL to Amazon RDS (and Vice-Versa) A typical scenario requiring replication from MySQL to RDS for instance could be an organization that is using RDS but wants to have a copy of their data stored in their onsite location to avoid vendor lock-in. With IT infrastructures, and ... Read More

Feed: Planet MySQL; Author: Severalnines; One of the most popular ways in achieving high availability for MySQL is replication. Replication has been around for many years, and became much more stable with the introduction of GTIDs. But even with these improvements, the replication process can break due to various reasons - for instance, when master and slave are out of sync because writes were sent directly to the slave. How do you troubleshoot replication issues, and how do you fix them?  In this blog post, we will discuss some of the common issues with replication and how to fix them ... Read More

Feed: Planet MySQL; Author: Saroj Tripathy; In this blog, we will discuss about how to setup MySQL NDB Cluster replication in a more secure way with the help of binary log and relay log encryption and a secure connection. These measures protect binary log dat in transit and at rest.Let’s create two MySQL NDB Clusters with the following environment, Here, one will be termed as ‘source’ cluster and the other one will be termed as ‘replica’ cluster.MySQL NDB Cluster version (Latest GA version)1 Management node4 Data nodes1 MySQLDsConfiguration slots for up to 4 additional API nodesStep 1: Start both of ... Read More

Feed: Planet MySQL; Author: Saroj Tripathy; In this blog, we will discuss, how to setup MySQL NDB Cluster replication through backup and restore method. This is bit tricky but interesting. The scenario here is, say user have a standalone cluster up and running, later there is a need to have a replication setup with an another empty cluster without shutting down the existing running cluster i.e. zero downtime. Then this backup and restore method will come in handy.Let’s create two MySQL NDB Cluster with the following environment, Here, one will be termed as ‘source’ cluster and the other one will ... Read More

Feed: Planet MySQL; Author: Saroj Tripathy; In this blog, we will discuss about bidirectional replication between two NDB clusters. With this topology, user can do transaction simultaneously from both the clusters on the same database objects.Let’s create two MySQL NDB Cluster with the following environment, Here, both will be termed as ‘source’ cluster as well as ‘replica’ cluster as we will do replication from both the sides.MySQL NDB Cluster version (Latest GA version)1 Management node4 Data nodes2 MySQLDsConfiguration slots for up to 4 additional API nodesReplication schema diagram:                    |-----------S1---------->>----------S3--------------|                    |           ... Read More