> On 03/04/2023 17:36 CEST Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote: > > On 4/3/23 08:11, Erik Wienhold wrote: > >> On 02/04/2023 17:40 CEST Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote: > >> > >> That is a long way from: > >> > >> jsonb @@ jsonpath → boolean > >> > >> Returns the result of a JSON path predicate check for the specified JSON > >> value. Only the first item of the result is taken into account. If the > >> result is not Boolean, then NULL is returned. > > > > What do you mean? I responded to the OP's question. It's not a suggestion > > to update the docs. Obviously it's quite a mouthful and needs to be boiled > > down for the docs. Any suggestions? > > For me I don't see how: > > Predicates have existence semantics, because their operands are item > sequences. Pairs of items from the left and right operand's sequences > are checked. TRUE returned only if any pair satisfying the condition is > found. In strict mode, even if the desired pair has already been found, > all pairs still need to be examined to check the absence of errors. If > any error occurs, UNKNOWN (analogous to SQL NULL) is returned. > > resolves to : > > Only the first item of the result is taken into account. > > In other words reconciling "TRUE returned only if any pair satisfying > the condition is found." and "...first item of the result..." I see. Thinking about it now, I believe that "first item of the result" is redundant (and causing the OP's confusion) because the path predicate produces only a single item: true, false, or null. That's what I wanted to show with the first two jsonb_path_query examples in my initial response, where the second example returns multiple items. I think the gist of @@ and json_path_match is: "Returns true if any JSON value at the given path matches the predicate. Returns NULL when not a path predicate or comparing different types." -- Erik
