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, PQERRORS_SQLSTATE } 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. The SQLSTATE
mode includes only the error severity and the SQLSTATE
error code, if one is available (if not, the output is like
TERSE mode).
Changing the verbosity setting 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.
The NEVER mode
never includes CONTEXT
, while ALWAYS always
includes it if available. In ERRORS mode (the
default), CONTEXT
fields are included only in error
messages, not in notices and warnings.
(However, if the verbosity setting is TERSE
or SQLSTATE, CONTEXT
fields
are omitted regardless of the context display mode.)
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);
Each line consists of: an optional timestamp, a direction indicator
(F
for messages from client to server
or B
for messages from server to client),
message length, message type, and message contents.
Non-message contents fields (timestamp, direction, length and message type)
are separated by a tab. Message contents are separated by a space.
Protocol strings are enclosed in double quotes, while strings used as data
values are enclosed in single quotes. Non-printable chars are printed as
hexadecimal escapes.
Further message-type-specific detail can be found in
Section 55.7.
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.
PQsetTraceFlags
Controls the tracing behavior of client/server communication.
void PQsetTraceFlags(PGconn *conn, int flags);
flags
contains flag bits describing the operating mode
of tracing.
If flags
contains PQTRACE_SUPPRESS_TIMESTAMPS
,
then the timestamp is not included when printing each message.
If flags
contains PQTRACE_REGRESS_MODE
,
then some fields are redacted when printing each message, such as object
OIDs, to make the output more convenient to use in testing frameworks.
This function must be called after calling PQtrace
.
PQuntrace
Disables tracing started by PQtrace
.
void PQuntrace(PGconn *conn);