Function Auxiliary Data

Function Auxiliary Data

void *sqlite3_get_auxdata(sqlite3_context*, int N);
void sqlite3_set_auxdata(sqlite3_context*, int N, void*, void (*)(void*));

These functions may be used by (non-aggregate) SQL functions to associate metadata with argument values. If the same value is passed to multiple invocations of the same SQL function during query execution, under some circumstances the associated metadata may be preserved. An example of where this might be useful is in a regular-expression matching function. The compiled version of the regular expression can be stored as metadata associated with the pattern string. Then as long as the pattern string remains the same, the compiled regular expression can be reused on multiple invocations of the same function.

The sqlite3_get_auxdata(C,N) interface returns a pointer to the metadata associated by the sqlite3_set_auxdata(C,N,P,X) function with the Nth argument value to the a