DbTypeToPostgreSqlStringNameResolver
This IResolver<DbType, string> implementation converts a .NET DbType into its equivalent PostgreSQL SQL type name (e.g. DbType.String → TEXT, DbType.Int32 → INTEGER, DbType.Binary/DbType.Byte → BYTEA). It is used internally by PostgreSqlConvertFieldResolver to build CAST(...) expressions.
Usability
var resolver = new DbTypeToPostgreSqlStringNameResolver();
var typeName = resolver.Resolve(DbType.Int64); // "BIGINT"