On 12/12/2018 08:32, Richard Guo wrote:
> This small revise is not expected to bring performance improvements, but
> can improve the readability of the code that for empty relids, the qual
> is always considered as being not-outerjoin_delayed.
I think code readability and maintainability would be improved by having
fewer special cases and fast paths. In this particular case, I'd even
remove the existing fast path and just let the subsequent loop run zero
times. I doubt there is a performance benefit to the existing coding.
And if there is no performance benefit, then it's not really a fast
path, just another path.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services