The synchronization delay from a cloud database SQL Server master database to a read-only database refers to the time gap between when data is written or updated in the primary (master) database and when those changes are replicated and become available in the read-only (secondary) database. This delay is influenced by factors such as network latency, the volume of transactions, the replication mechanism used, and the workload on both the primary and secondary databases.
SQL Server offers several replication methods, including Always On Availability Groups, Transactional Replication, and Database Mirroring (deprecated in newer versions). Always On Availability Groups, for example, provide synchronous and asynchronous replication options. Synchronous replication ensures that data is written to both the primary and secondary databases before the transaction is committed, minimizing data loss but potentially increasing latency. Asynchronous replication allows the primary database to commit transactions without waiting for confirmation from the secondary database, reducing latency but increasing the risk of data loss in case of a failure.
Example:
Suppose you have an e-commerce application using SQL Server in the cloud. The master database handles all write operations (e.g., order placements, inventory updates), while read-only databases serve customer queries (e.g., product listings, order statuses). If the synchronization delay is 2 seconds, a customer might see their order status as "processing" for 2 seconds after it has actually been updated to "shipped" in the master database.
For cloud-based SQL Server solutions, Tencent Cloud's SQL Server Always On Availability Groups can be used to minimize synchronization delay while ensuring high availability and disaster recovery. It supports both synchronous and asynchronous replication, allowing you to balance performance and data consistency based on your application's requirements. Additionally, Tencent Cloud's high-performance network infrastructure helps reduce latency between the primary and secondary databases.