Re: Improve examples for range operators

2019-02-21 Thread Bruce Momjian
On Wed, Feb 20, 2019 at 12:27:26PM +, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
> 
> Page: https://www.postgresql.org/docs/11/functions-range.html
> Description:
> 
> Hi.
> 
> It would be nice if next examples:
> 
> < >>strictly right of   int8range(50,60) >> int8range(20,30)t
> & int8range(18,20)
>   t
> &>does not extend to the left of  int8range(7,20) &> int8range(5,10)  
> t
> 
> are extended by:
> **not** strictly left of, **not** strictly right of, **extends** to the
> right of, **extends** to the left of
> 
> Because without manual experiments I can not imagine the ranges that cause
> 'false' result for the examples above.

Well, they are not technically negatives of each other.  << means the
first is all left of the second, while &< means that it doesn't go to
the right of the second, e.g.,

SELECT int8range(1,10) &< int8range(100,110);
 ?column?
--
 t

SELECT int8range(1,105) &< int8range(100,110);
 ?column?
--
 t

SELECT int8range(1,200) &< int8range(100,110);
 ?column?
--
 f

Notice it changed from true to false and none of these was strictly to
the right.

-- 
  Bruce Momjian  http://momjian.us
  EnterpriseDB http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
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Improve examples for range operators

2019-02-20 Thread PG Doc comments form
The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/11/functions-range.html
Description:

Hi.

It would be nice if next examples:

<<  strictly left ofint8range(1,10) << int8range(100,110)   t
>>  strictly right of   int8range(50,60) >> int8range(20,30)t
&<  does not extend to the right of int8range(1,20) &< 
int8range(18,20)
t
&>  does not extend to the left of  int8range(7,20) &> int8range(5,10)  
t

are extended by:
**not** strictly left of, **not** strictly right of, **extends** to the
right of, **extends** to the left of

Because without manual experiments I can not imagine the ranges that cause
'false' result for the examples above.

Thank you.