The behaviour of these functions is affected by settings in php.ini.
|apd.statement_tracing||"0"||PHP_INI_ALL||Available since apd 0.9.|
Here's a short explanation of the configuration directives.
Sets the directory in which APD writes profile dump files. You can specify an absolute path or a relative path.
You can specify a different directory as an argument to apd_set_pprof_trace().
Specfies whether or not to do per-line tracings. Turning this on (1) will impact the performance of your application.