exec_cache

# File activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb, line 1164
        def exec_cache(sql, binds)
          begin
            stmt_key = prepare_statement sql

            # Clear the queue
            @connection.get_last_result
            @connection.send_query_prepared(stmt_key, binds.map { |col, val|
              type_cast(val, col)
            })
            @connection.block
            @connection.get_last_result
          rescue PGError => e
            # Get the PG code for the failure.  Annoyingly, the code for
            # prepared statements whose return value may have changed is
            # FEATURE_NOT_SUPPORTED.  Check here for more details:
            # http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/utils/cache/plancache.c#l573
            code = e.result.result_error_field(PGresult::PG_DIAG_SQLSTATE)
            if FEATURE_NOT_SUPPORTED == code
              @statements.delete sql_key(sql)
              retry
            else
              raise e
            end
          end
        end