Horton

Re: SQL/JSON path issues/questions

Alexander Korotkov <a.korotkov@postgrespro.ru>

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From: Alexander Korotkov <a.korotkov@postgrespro.ru>
To: Liudmila Mantrova <l.mantrova@postgrespro.ru>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Thom Brown <thom@linux.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2019-06-28T03:47:59Z
Lists: pgsql-hackers 
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?

>    Each filter expression can provide one or more filters
>    that are applied to the result of the path evaluation.


So additionally to filter condition and filter expression we introduce
the notion of just filter.  What is it?  Could we make it without
introduction of new notion?

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. Fixes for jsonpath filter expression elements table in docs

  2. Assorted fixes for jsonpath documentation

  3. Fix description for $varname jsonpath variable

  4. Improve documentation for jsonpath like_regex predicate

  5. Support 'q' flag in jsonpath 'like_regex' predicate