void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*); void *sqlite3_profile(sqlite3*, void(*xProfile)(void*,const char*,sqlite3_uint64), void*);
These routines register callback functions that can be used for tracing and profiling the execution of SQL statements.
The callback function registered by sqlite3_trace() is invoked at various times when an SQL statement is being run by sqlite3_step(). The sqlite3_trace() callback is invoked with a UTF-8 rendering of the SQL statement text as the statement first begins executing. Additional sqlite3_trace() callbacks might occur as each triggered subprogram is entered. The callbacks for triggers contain a UTF-8 SQL comment that identifies the trigger.
The callback function registered by sqlite3_profile() is invoked as each SQL statement finishes. The profile callback contains the original statement text and an estimate of wall-clock time of how long that statement took to run. The profile callback time is in units of nanoseconds, however the current implementation is only capable of millisecond resolution so the six least significant digits in the time are meaningless. Future versions of SQLite might provide greater resolution on the profiler callback. The sqlite3_profile() function is considered experimental and is subject to change in future versions of SQLite.