sqlite3_int64 sqlite3_memory_used(void); sqlite3_int64 sqlite3_memory_highwater(int resetFlag);
The sqlite3_memory_used() routine returns the number of bytes of memory currently outstanding (malloced but not freed). The sqlite3_memory_highwater() routine returns the maximum value of sqlite3_memory_used() since the high-water mark was last reset. The values returned by sqlite3_memory_used() and sqlite3_memory_highwater() include any overhead added by SQLite in its implementation of sqlite3_malloc(), but not overhead added by the any underlying system library routines that sqlite3_malloc() may call.
The memory high-water mark is reset to the current value of sqlite3_memory_used() if and only if the parameter to sqlite3_memory_highwater() is true. The value returned by sqlite3_memory_highwater(1) is the high-water mark prior to the reset.