Other

PostgreSQL extensions

The Npgsql EF Core provider allows you to specify PostgreSQL extensions that should be set up in your database. Simply use HasPostgresExtension in your context's OnModelCreating method:

protected override void OnModelCreating(ModelBuilder modelBuilder)
    => modelBuilder.HasPostgresExtension("hstore");

Execution Strategy

The Npgsql EF Core provider provides a retrying execution strategy, which will attempt to detect most transient PostgreSQL/network errors and will automatically retry your operation. To enable, place the following code in your context's OnModelConfiguring:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder.UseNpgsql(
        "<connection_string>",
        options => options.EnableRetryOnFailure());

This strategy relies on the IsTransient property of NpgsqlException.

Certificate authentication

The Npgsql allows you to provide a callback for verifying the server-provided certificates, and to provide a callback for providing certificates to the server. The latter, if properly set up on the PostgreSQL side, allows you to do client certificate authentication - see the Npgsql docs and also the PostgreSQL docs on setting this up.

The Npgsql EF Core provider allows you to set these two callbacks on the DbContextOptionsBuilder as follows:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder.UseNpgsql(
        "<connection_string>",
        options =>
        {
            options.RemoteCertificateValidationCallback(MyCallback1);
            options.ProvideClientCertificatesCallback(MyCallback2);
        });

You may also consider passing Trust Server Certificate=true in your connection string to make Npgsql accept whatever certificate your PostgreSQL provides (useful for self-signed certificates).

Caution

When specifying the options via OnConfiguring, make sure that the callbacks you pass in are static methods. Passing in instance methods causes EF Core to create a new service provider for each context instance, which can degrade performance in a significant way.

CockroachDB Interleave In Parent

If you're using CockroachDB, the Npgsql EF Core provider exposes its "interleave in parent" feature. Use the following code:

protected override void OnModelCreating(ModelBuilder modelBuilder)
    => modelBuilder.Entity<Customer>()
                   .UseCockroachDbInterleaveInParent(
                        typeof(ParentEntityType),
                        new List<string> { "prefix_column_1", "prefix_column_2" });