Missing index (ARCH207)

Key dotnet.ef.missing-index · Severity info · Category ef

Columns frequently used in filters or joins without an index cause full table scans.

Incorrect

modelBuilder.Entity<User>(e =>
{
    e.Property(u => u.Email).IsRequired();
});
// queried by Email constantly, but no index

Correct

modelBuilder.Entity<User>(e =>
{
    e.Property(u => u.Email).IsRequired();
    e.HasIndex(u => u.Email);
});

Fix

Define an index on the property with HasIndex.