Read-Scale Out Data Latency Limits in Business Critical Tier

Asynchronous Replication Behavior

Azure SQL Database Read-Scale Out provides a read-only replica for offloading reporting and analytical workloads from the primary node. This feature is available in the Premium and Business Critical service tiers, utilizing asynchronous replication to keep the secondary node updated.

Consistency Constraints

Because the replication is asynchronous, there is an inherent risk of data latency where the read-only replica may not immediately reflect the most recent commits from the primary replica. This creates a challenge for applications that require strong consistency across both read-write and read-only connections.

When routing traffic via ApplicationIntent=ReadOnly, the degree of lag is not explicitly capped by a user-configurable threshold.

• How can the current replication lag be measured programmatically to ensure data freshness?
• Are there documented mechanisms to force a read-only connection to wait for a specific transaction log sequence number (LSN)?