| PostgreSQL 9.6.19 Documentation | |||
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These functions control miscellaneous details of libpq's behavior.
PQclientEncoding
     Returns the client encoding.
int PQclientEncoding(const PGconn *conn);
Note that it returns the encoding ID, not a symbolic string such as EUC_JP. If unsuccessful, it returns -1. To convert an encoding ID to an encoding name, you can use:
char *pg_encoding_to_char(int encoding_id);
PQsetClientEncoding
     Sets the client encoding.
int PQsetClientEncoding(PGconn *conn, const char *encoding);
      conn is a connection to the server,
      and encoding is the encoding you want to
      use. If the function successfully sets the encoding, it returns 0,
      otherwise -1. The current encoding for this connection can be
      determined by using PQclientEncoding.
     
PQsetErrorVerbosity
           Determines the verbosity of messages returned by
      PQerrorMessage and PQresultErrorMessage.
typedef enum
{
    PQERRORS_TERSE,
    PQERRORS_DEFAULT,
    PQERRORS_VERBOSE
} PGVerbosity;
PGVerbosity PQsetErrorVerbosity(PGconn *conn, PGVerbosity verbosity);
      PQsetErrorVerbosity sets the verbosity mode, returning
      the connection's previous setting.  In TERSE mode,
      returned messages include severity, primary text, and position only;
      this will normally fit on a single line.  The default mode produces
      messages that include the above plus any detail, hint, or context
      fields (these might span multiple lines).  The VERBOSE
      mode includes all available fields.  Changing the verbosity does not
      affect the messages available from already-existing
      PGresult objects, only subsequently-created ones.
      (But see PQresultVerboseErrorMessage if you
      want to print a previous error with a different verbosity.)
     
PQsetErrorContextVisibility
           Determines the handling of CONTEXT fields in messages
      returned by PQerrorMessage
      and PQresultErrorMessage.
typedef enum
{
    PQSHOW_CONTEXT_NEVER,
    PQSHOW_CONTEXT_ERRORS,
    PQSHOW_CONTEXT_ALWAYS
} PGContextVisibility;
PGContextVisibility PQsetErrorContextVisibility(PGconn *conn, PGContextVisibility show_context);
      PQsetErrorContextVisibility sets the context display mode,
      returning the connection's previous setting.  This mode controls
      whether the CONTEXT field is included in messages
      (unless the verbosity setting is TERSE, in which
      case CONTEXT is never shown).  The NEVER mode
      never includes CONTEXT, while ALWAYS always
      includes it if available.  In ERRORS mode (the
      default), CONTEXT fields are included only for error
      messages, not for notices and warnings.  Changing this mode does not
      affect the messages available from
      already-existing PGresult objects, only
      subsequently-created ones.
      (But see PQresultVerboseErrorMessage if you
      want to print a previous error with a different display mode.)
     
PQtrace
     Enables tracing of the client/server communication to a debugging file stream.
void PQtrace(PGconn *conn, FILE *stream);
Note: On Windows, if the libpq library and an application are compiled with different flags, this function call will crash the application because the internal representation of the FILE pointers differ. Specifically, multithreaded/single-threaded, release/debug, and static/dynamic flags should be the same for the library and all applications using that library.
PQuntrace
           Disables tracing started by PQtrace.
void PQuntrace(PGconn *conn);