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32.10. Control Functions
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32.10. Control Functions

These functions control miscellaneous details oflibpq's behavior.

PQclientEncoding

Returns the client encoding.

int PQclientEncoding(const PGconn *conn);

Note that it returns the encoding ID, not a symbolic string such asEUC_JP. If unsuccessful, it returns -1. To convert an encoding ID to an encoding name, you can use:

char *pg_encoding_to_char(intencoding_id);

PQsetClientEncoding

Sets the client encoding.

int PQsetClientEncoding(PGconn *conn, const char *encoding);

conn is a connection to the server, andencoding 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 usingPQclientEncoding.

PQsetErrorVerbosity

Determines the verbosity of messages returned byPQerrorMessage andPQresultErrorMessage.

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. InTERSE 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). TheVERBOSE mode includes all available fields. Changing the verbosity does not affect the messages available from already-existingPGresult objects, only subsequently-created ones. (But seePQresultVerboseErrorMessage if you want to print a previous error with a different verbosity.)

PQsetErrorContextVisibility

Determines the handling ofCONTEXT fields in messages returned byPQerrorMessage andPQresultErrorMessage.

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 theCONTEXT field is included in messages (unless the verbosity setting isTERSE, in which caseCONTEXT is never shown). TheNEVER mode never includesCONTEXT, whileALWAYS always includes it if available. InERRORS 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-existingPGresult objects, only subsequently-created ones. (But seePQresultVerboseErrorMessage 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 thelibpq library and an application are compiled with different flags, this function call will crash the application because the internal representation of theFILE 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 byPQtrace.

void PQuntrace(PGconn *conn);


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32.9. Functions Associated with theCOPY Command Home 32.11. Miscellaneous Functions
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