Edison  Stark

Edison Stark


Configuring SQL Server replication for distribution databases


In the earlier article (see TOC at the bottom), we explored how you can add the publisher and subscriber database in a high availability configuration using SQL Server Always On Availability Groups. It used a remote distributor for transactional replication.

Suppose the publisher and subscriber databases are on [SQLAG1\INST1] node, and failover happens to the node [SQLAG2\INST2]. In this case, the transactional replication works fine without any issues. It provided high resilience for the publisher and subscriber database.

What about the distribution database? Can we add it to the availability group? In this article, let’s explore the steps required for the distribution database AG.

Overview of the distribution database in the SQL Server Always On Availability Groups

We can add the replication distribution database in the availability group for high availability starting from SQL Server 2017 CU6 and SQL Server 2016 SP2-CU3. It requires special considerations for adding the distribution database.

  • You must use a SQL listener for the distribution configuration
  • It creates SQL jobs with the listener’s name
  • It creates a new job to monitor the status of the distribution database in primary or secondary AG
  • SQL Server automatically disables and enables the jobs based on the primary replica. For example, if the distribution database is on the SQLAG1, jobs are enabled on the SQLAG1 instance. In the case of DB failover, jobs got disabled on the SQLAG1 and enabled on the SQLAG2 instance
  • The publisher and distributor database cannot exist in an instance
  • We cannot use merge, Peer-To-Peer replication
  • All replication databases (publisher, subscriber, and distributor) should be a minimum of SQL Server 2017 CU6 and SQL Server 2016 SP2-CU3
  • We can use both synchronous and asynchronous data synchronization for the distribution database
  • We cannot use the SSMS wizard for the distribution database AG configuration. It needs to set up using the scripts
  • We cannot use an existing distribution database for the AG configuration. If the replication is already configured, we need to break the replication first and configure it using the scripts for AG configuration
  • The secondary replica of the distribution database should allow read-only connections
  • You should use the same domain account in all replica of the distribution database AG

Environmental details

In this article, we use the following environment.

Existing AG configuration:

We configure the distribution database in a new availability group on the following replicas.

  • Primary Replica: SQLAG1\INST1
  • Secondary Replica: SQLAG2\INST2
  • Existing AG database: DBARepository

For this article, we use a standalone instance for the publisher and subscriber.

Publisher and Subscriber: SQLNode3\INST3

Therefore, the overall configuration in terms of the SQL Server replication topology is as below.:

  • Publication Server: SQLNode3\INST3
  • Subscription Server: SQLNode3\INST3
  • Distribution Server: AG replica ( SQLAG1\INST1 & SQLAG2\INST2)

You can use the previous articles in the series to prepare a similar environment.

Steps to configure SQL Server replication distribution database in SQL Server Always On Availability Groups

Note: You can find the script attached at the bottom of the article.

#always on availability groups #installation #setup and configuration #replication #database

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Configuring SQL Server replication for distribution databases
Cayla  Erdman

Cayla Erdman


Introduction to Structured Query Language SQL pdf

SQL stands for Structured Query Language. SQL is a scripting language expected to store, control, and inquiry information put away in social databases. The main manifestation of SQL showed up in 1974, when a gathering in IBM built up the principal model of a social database. The primary business social database was discharged by Relational Software later turning out to be Oracle.

Models for SQL exist. In any case, the SQL that can be utilized on every last one of the major RDBMS today is in various flavors. This is because of two reasons:

1. The SQL order standard is genuinely intricate, and it isn’t handy to actualize the whole standard.

2. Every database seller needs an approach to separate its item from others.

Right now, contrasts are noted where fitting.

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Ruth  Nabimanya

Ruth Nabimanya


System Databases in SQL Server


In SSMS, we many of may noticed System Databases under the Database Folder. But how many of us knows its purpose?. In this article lets discuss about the System Databases in SQL Server.

System Database

Fig. 1 System Databases

There are five system databases, these databases are created while installing SQL Server.

  • Master
  • Model
  • MSDB
  • Tempdb
  • Resource
  • This database contains all the System level Information in SQL Server. The Information in form of Meta data.
  • Because of this master database, we are able to access the SQL Server (On premise SQL Server)
  • This database is used as a template for new databases.
  • Whenever a new database is created, initially a copy of model database is what created as new database.
  • This database is where a service called SQL Server Agent stores its data.
  • SQL server Agent is in charge of automation, which includes entities such as jobs, schedules, and alerts.
  • The Tempdb is where SQL Server stores temporary data such as work tables, sort space, row versioning information and etc.
  • User can create their own version of temporary tables and those are stored in Tempdb.
  • But this database is destroyed and recreated every time when we restart the instance of SQL Server.
  • The resource database is a hidden, read only database that holds the definitions of all system objects.
  • When we query system object in a database, they appear to reside in the sys schema of the local database, but in actually their definitions reside in the resource db.

#sql server #master system database #model system database #msdb system database #sql server system databases #ssms #system database #system databases in sql server #tempdb system database

Ruth  Nabimanya

Ruth Nabimanya


List of Available Database for Current User In SQL Server


When working in the SQL Server, we may have to check some other databases other than the current one which we are working. In that scenario we may not be sure that does we have access to those Databases?. In this article we discuss the list of databases that are available for the current logged user in SQL Server

Get the list of database

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Brain  Crist

Brain Crist


SCHEMAS in SQL Server -MS SQL Server – Zero to Hero Query Master


This is part 3 of “MS SQL Server- Zero to Hero” and in this article, we will be discussing about the SCHEMAS in SQL SERVER. Before getting into this article, please consider to visit previous articles in this series from below,

A glimpse of previous articles
Part 1

In part one, we learned the basics of data, database, database management system, and types of DBMS and SQL.

Part 2
  • We learned to create a database and maintain it using SQL statements.
  • Best practice methods were also mentioned.

#sql server #benefits of schemas #create schema in sql #database schemas #how to create schema in sql server #schemas #schemas in sql server #sql server schemas #what is schema in sql server

Ray  Patel

Ray Patel


Python Packages in SQL Server – Get Started with SQL Server Machine Learning Services


When installing Machine Learning Services in SQL Server by default few Python Packages are installed. In this article, we will have a look on how to get those installed python package information.

Python Packages

When we choose Python as Machine Learning Service during installation, the following packages are installed in SQL Server,

  • revoscalepy – This Microsoft Python package is used for remote compute contexts, streaming, parallel execution of rx functions for data import and transformation, modeling, visualization, and analysis.
  • microsoftml – This is another Microsoft Python package which adds machine learning algorithms in Python.
  • Anaconda 4.2 – Anaconda is an opensource Python package

#machine learning #sql server #executing python in sql server #machine learning using python #machine learning with sql server #ml in sql server using python #python in sql server ml #python packages #python packages for machine learning services #sql server machine learning services