Before the patch, queries like:
SELECT 1 FROM dual UNION SELECT 2 FROM dual
were failing badly, with everything but the first numeric element
being ignored by the optimization.
So, being conservative, now we reduce the query being analysed,
ignoring any subquery, inline view (anything within parenthesis
in general) and, in the remaining query, if a boolean query (UNION,
MINUS, INTERSECT...) is found, we don't apply any optimization.
* We need to use is_numeric() in this case as is_int() would never
return true.
* Extend the supported cases, add support for SQL consisting just of
numerical value or selectinga numerical constant.
* Do not rely on any particulat letter case in provided SQL.
* Add unit tests for the new method. Even when it is a protected one, it
is an essential unit to be tested on its own.
Eloy Lafuente (stronk7)