Re: hard parse?

On Thu, Sep 21, 2017 at 5:48 AM, Peter Koukoulis <pkoukoulis(at)gmail(dot)com>
wrote:

> Hi
>
> I have a query where a filter would always be negative, how many steps,
> out these:
>
> - parsing and syntax check
> - semantic analysis
> - transformation process (query rewrite based on system or
> user-defined rules)
> - query optimization
> - execution
>
> would be performed or not? Also, where in the documentation can I found
> out which of the above phases would be performed?
>
> For example, for a query such as the following:
>
> select x,y from test1 where 1=0;
>
>
I'm inferring behavior here but...​

​All of them. You are still going to get a result set with zero records
and the correct column structure. i.e., "Execution". None of the other
stuff can be skipped in getting to engine to that point. With a "always
false" predicate and that simple of a query structure most of the other
stuff, including execution, is probably performed is seemingly zero time
but it still has to work through that step of the process - if nothing else
than to move through an if-branch to decide that nothing material needs to
be done.

David J.
​