Transactional Replication

Transactional Replication

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Transactional replication is a database replication technique used in distributed database systems to ensure consistent data across multiple database instances. It is a process of copying and synchronizing data changes from a source database (publisher) to one or more destination databases (subscribers) in real-time.

Here’s how transactional replication works:

  1. Publication: The process begins by defining a publication on the source database. The publication specifies the objects (tables, views, etc.) that will be replicated and the subscribers that will receive the replicated data.
  2. Snapshot: Initially, a snapshot of the published data is taken, which includes the current state of the published objects. This snapshot is then transferred to the subscribers to initialize their databases.
  3. Log Reader: The source database maintains a log of all data changes (inserts, updates, and deletes) made to the published objects. The log reader component continuously monitors this log and captures the data changes.
  4. Distribution: The captured data changes are stored in a distribution database. The distribution database acts as a buffer and keeps track of the replicated transactions. It organizes the data changes into logical units called transactions.
  5. Distribution Agent: The distribution agent reads the replicated transactions from the distribution database and applies them to the subscriber databases. It ensures that the replicated data changes are applied in the same order and consistency as they occurred on the source database.
  6. Commit: Once the data changes are successfully applied to the subscribers, an acknowledgement is sent back to the source database to confirm the commit. This ensures that the changes are durably replicated and maintained across all the databases.

Transactional replication offers near real-time data synchronization between databases, making it suitable for scenarios where data consistency is critical, such as in distributed applications, reporting systems, or data warehousing. It provides a reliable and scalable solution for distributing data across multiple database instances while maintaining transactional integrity.

It’s important to note that transactional replication requires a robust network infrastructure and careful monitoring to handle any potential conflicts, latency, or network failures that may impact the replication process.

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