unsafe, because this would require predicting every operation which the
function could possibly perform. In general, this is equivalent to the
Halting Problem and therefore impossible. Even for simple functions
- where it conceivably be done, we do not try, since this would be expensive
+ where it could conceivably be done, we do not try, since this would be expensive
and error-prone. Instead, all user-defined functions are assumed to
be parallel unsafe unless otherwise marked. When using
<xref linkend="sql-createfunction"/> or