On Fri, Jun 28, 2019 at 8:10 AM Alvaro Herrera <alvhe...@2ndquadrant.com> wrote: > > On 2019-Jun-28, Alexander Korotkov wrote: > > > On Tue, Jun 25, 2019 at 6:38 PM Liudmila Mantrova > > <l.mantr...@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.
Yes, this is what I used in my talk http://www.sai.msu.su/~megera/postgres/talks/jsonpath-ibiza-2019.pdf > > Maybe we should stick with the standard terminology ... Sure. As for the jsonpath documentation, I think we should remember, that jsonpath is a part of SQL/JSON, and in the following releases we will expand documentation to include SQL/JSON functions, so I suggest to have one chapter SQL/JSON with following structure: 1. Introduction 1.1 SQL/JSON data model 1.2 SQL/JSON path language 1.3 <SQL/JSON functions> -- to be added 2. PostgreSQL implementation 2.1 jsonpath data type -- link from json data types 2.2 jsonpath functions and operators -- link from functions 2.3 Indexing I plan to work on a separate chapter "JSON handling in PostgreSQL" for PG13, which includes JSON(b) data types, functions, indexing and SQL/JSON. > > -- > Álvaro Herrera https://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services > > -- Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
