PollyNpgsql 1.0.2

PollyNpgsql

Polly v8 resilience for Npgsql (PostgreSQL) — retry, timeout, and circuit-breaker for NpgsqlConnection queries and commands, plus a built-in PostgresTransientErrors predicate covering all common PostgreSQL transient SQLSTATE codes. Zero changes to your existing SQL.

// One line of setup
var resilient = connection.WithPolly(pipeline =>
    pipeline
        .AddRetry(new RetryStrategyOptions
        {
            MaxRetryAttempts = 3,
            ShouldHandle = PostgresTransientErrors.IsTransient, // built-in ✔
        })
        .AddTimeout(TimeSpan.FromSeconds(10)));

// Use exactly like NpgsqlConnection
var orders = await resilient.QueryAsync(
    "SELECT id, total FROM orders WHERE customer_id = $1",
    r => new Order(r.GetInt32(0), r.GetDecimal(1)),
    parameters: [new NpgsqlParameter { Value = customerId }]);

Installation

dotnet add package PollyNpgsql

Targets net6.0, net8.0, and net9.0. Dependencies: Polly.Core 8.*, Npgsql 9.*, Microsoft.Extensions.DependencyInjection.Abstractions 8.*

PostgresTransientErrors — the key feature

Knowing which PostgreSQL errors are safe to retry is the hard part. PollyNpgsql ships a pre-built PostgresTransientErrors.IsTransient predicate so you don't have to look up SQLSTATE codes.

new RetryStrategyOptions
{
    MaxRetryAttempts = 3,
    ShouldHandle = PostgresTransientErrors.IsTransient,
}

The raw set is also available if you need to extend it:

// Add custom codes
var myStates = PostgresTransientErrors.SqlStates.ToHashSet();
myStates.Add("57014"); // query_canceled (e.g. statement_timeout)

new RetryStrategyOptions
{
    ShouldHandle = new PredicateBuilder().Handle<NpgsqlException>(ex =>
        ex is PostgresException pg && myStates.Contains(pg.SqlState))
}

Quick start

Inline pipeline

using PollyNpgsql;

await using var connection = new NpgsqlConnection(connectionString);
var resilient = connection.WithPolly(pipeline =>
    pipeline
        .AddRetry(new RetryStrategyOptions
        {
            MaxRetryAttempts = 3,
            Delay = TimeSpan.FromMilliseconds(200),
            BackoffType = DelayBackoffType.Exponential,
            ShouldHandle = PostgresTransientErrors.IsTransient,
        })
        .AddTimeout(TimeSpan.FromSeconds(30)));

await resilient.OpenAsync();

// Execute non-query
await resilient.ExecuteAsync(
    "INSERT INTO events (type, payload) VALUES ($1, $2)",
    parameters: [new("type") { Value = "OrderPlaced" }, new("payload") { Value = json }]);

// Query with mapper
var orders = await resilient.QueryAsync(
    "SELECT id, total FROM orders WHERE customer_id = $1",
    reader => new Order(reader.GetInt32(0), reader.GetDecimal(1)),
    parameters: [new NpgsqlParameter { Value = customerId }]);

// Scalar
var count = await resilient.ExecuteScalarAsync<long>("SELECT COUNT(*) FROM orders");

Dependency injection

// Program.cs
builder.Services.AddScoped(_ => new NpgsqlConnection(connectionString));

builder.Services.AddPollyNpgsql(pipeline =>
    pipeline
        .AddRetry(new RetryStrategyOptions
        {
            MaxRetryAttempts = 3,
            Delay = TimeSpan.FromMilliseconds(200),
            BackoffType = DelayBackoffType.Exponential,
            ShouldHandle = PostgresTransientErrors.IsTransient,
        })
        .AddTimeout(TimeSpan.FromSeconds(30))
        .AddCircuitBreaker(new CircuitBreakerStrategyOptions
        {
            FailureRatio = 0.5,
            MinimumThroughput = 10,
            SamplingDuration = TimeSpan.FromSeconds(30),
            BreakDuration = TimeSpan.FromSeconds(15),
        }));

// Repository
public class OrderRepository(NpgsqlConnection db, ResiliencePipeline pipeline)
{
    public async Task<List<Order>> GetByCustomerAsync(int customerId)
    {
        var resilient = db.WithPolly(pipeline);
        await resilient.OpenAsync();
        return await resilient.QueryAsync(
            "SELECT id, total FROM orders WHERE customer_id = $1",
            r => new Order(r.GetInt32(0), r.GetDecimal(1)),
            parameters: [new NpgsqlParameter { Value = customerId }]);
    }
}

Supported operations

Pipeline order

[Timeout] → [Retry] → [Circuit Breaker] → [Npgsql]

pipeline
    .AddTimeout(TimeSpan.FromSeconds(30))   // 1. Overall deadline
    .AddRetry(retryOptions)                 // 2. Retry transient failures
    .AddCircuitBreaker(cbOptions)           // 3. Open circuit under load

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PollyAzureQueueStorage		Polly v8 resilience pipelines for Azure Queue Storage — retry, timeout, and circuit-breaker for Azure.Storage.Queues QueueClient
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PollyAzureServiceBus		Polly v8 resilience for Azure Service Bus — retry, circuit breaker, and timeout for sending and receiving messages
PollyAzureBlob		Polly v8 resilience pipelines for Azure Blob Storage — wrap BlobClient and BlobContainerClient operations with retry, timeout, circuit-breaker, and more using ResilientBlobClient and ResilientBlobContainerClient decorators
PollyAzureTableStorage		Polly v8 resilience pipelines for Azure Table Storage — retry, timeout, and circuit-breaker for Azure.Data.Tables TableClient

💼 Need .NET consulting?

The author of this package is available for consulting on Polly v8 resilience, Azure cloud architecture, and clean .NET design.

→ solidqualitysolutions.com · LinkedIn

License

MIT