Re: Change in order of criteria - reg

On Wed, Jun 1, 2016 at 12:07 AM, sri harsha <sriharsha9992(at)gmail(dot)com> wrote:

>
> Hi,
>
> In PostgreSQL , does the order in which the criteria is given matter
> ?? For example
>
> Query 1 : Select * from TABLE where a > 5 and b < 10;
>
> Query 2 : Select * from TABLE where b <10 and a > 5;
>
> Are query 1 and query 2 the same in PostgreSQL or different ?? If its
> different , WHY ??
>
>
​Why are you asking? Do you have any context in which you want to measure
"sameness"?

I
​ was thinking that pg_stat_statements might treat them differently but the
comparison there is object based, not string based, so these should end up
with the same hash.

​If everything is working correctly there will be no observable and
persistent difference between executing those exact two queries as far as
PostgreSQL is concerned. You might find a difference in the parse tree
representation where a > 5 is on the left leaf of a branch in one query but
on the right leaf in the other...

David J.