Transient failures happen — in the cloud (Azure SQL) and on-prem. A resilient connection strategy lets your app recover gracefully instead of crashing: it waits smartly, retries safely, and doesn’t pound the database when it’s truly unavailable.
Why care?
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Less downtime during patching/scaling/failovers
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Smoother UX — fewer “please try again” moments for users
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Operational robustness against brief network glitches and load spikes
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Fewer cascading errors — keep transactions consistent and data clean
Transient vs. persistent errors
Transient errors (good candidates for retry):
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Brief network interruptions
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“Server busy”/throttling
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Deadlocks or timeouts due to temporary load
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Failovers during maintenance/patching
Persistent errors (should fail fast):
The point: classify the error, then do the right thing. Retries only help with transient faults.
Patterns you actually need
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Retry with exponential backoff + jitter (spreads load to avoid stampedes)
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Circuit Breaker (stop hammering when the DB is really down)
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Connection pooling (reduce login churn, lower latency)
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Timeouts & Cancellation (no infinite waits; play nice with callers)
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Idempotency (retries must not create duplicates or corrupt state)
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Always On optimization:
MultiSubnetFailover=Truein your connection string
Code: Async retry with backoff + jitter (C# / Microsoft.Data.SqlClient)
Below is a quick primer and a C# sample you can paste right in.
Usage
Production tips
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Log with structure (attempt, backoff, error codes, correlation ID).
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Bound retries (max attempts or a total time budget).
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Make writes idempotent or wrap in transactions that tolerate retries.
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Consider a Circuit Breaker (e.g., via Polly) around the most critical calls.
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Windows auth.
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Leverage SqlClient’s built-in retry (RetryLogicProvider) if you want a centralized policy.
Bottom line
Resilience isn’t a nice-to-have; it’s part of correctness in data access. With a thin layer of backoff-based retries, clear error classification, cancellation, and the right connection settings, your application will sail through the little storms that would otherwise dent availability and user experience.
