Re: SQL/JSON path issues/questions

On 2019-Jun-28, Alexander Korotkov wrote:

> On Tue, Jun 25, 2019 at 6:38 PM Liudmila Mantrova
> <l.mantrova@postgrespro.ru> wrote:
> > Thank you for the catch! Please see the modified version of patch 0004
> > attached.
> 
> I tried to review and revise the part related to filters, but I failed
> because I don't understand the notions used in the documentation.
> 
> What is the difference between filter expression and filter condition?
>  I can guess that filter expression contains question mark,
> parentheses and filter condition inside.  But this sentence is in
> contradiction with my guess: "A filter expression must be enclosed in
> parentheses and preceded by a question mark".  So, filter expression
> is inside the parentheses.  Then what is filter condition?  The same?

The SQL standard defines "JSON filter expressions" (in 9.39 of the 2016
edition).  It does not use either term "filter condition" nor bare
"filter"; it uses "JSON path predicate" which is the part of the JSON
filter expression that is preceded by the question mark and enclosed by
parens.

Maybe we should stick with the standard terminology ...

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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