.. efun:: int pg_query (string query)
  int pg_query (string query, int flags)
  :include: <pgsql.h>
  :optional:

  Queue a new query :arg:`query` to the database connection on the current object. Return the unique id of the query. The query result itself will be passed as argument to the callback function.

  :arg:`flags` can be one of these values:

  - :macro:`PG_RESULT_ARRAY`: Pass the query result as array.
  - :macro:`PG_RESULT_MAP`:   Pass the query result as mapping.

  The function is available only if the driver is compiled with PostgreSQL support. In that case, :macro:`__PGSQL__` is defined.

  .. todo:: should notes like the above be arguments to the optional flag? i.e., ``:optional: available if the driver is compiled with PostgreSQL support (in which case :macro:`__PGSQL__` is defined).``?

  The efun triggers a privilege violation ("pgsql", "pg_query").

  :history 3.3.445 introduced:
  :history 3.3.640 changed: added the privilege violation.

  .. seealso:: :concept:`pgsql`, :efun:`pg_connect`, :efun:`pg_conv_string`, :efun:`pg_pending`, :efun:`pg_close`, :master:`privilege_violation`