Re: Abnormal JSON query performance

On Mon, May 14, 2018 at 8:53 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> "David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> > On Mon, May 14, 2018 at 7:49 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> SELECT ... FROM ...some tables...,
> >> jsonb_to_record(jsonbcol) AS j(id int, name text, price numeric)
> >> WHERE ...
> >>
> >> which is something you can do today.
>
> > ​Indeed you can - could you please point to the docs for that one?
>
> https://www.postgresql.org/docs/current/static/functions-
> json.html#FUNCTIONS-JSON-PROCESSING-TABLE
>
> ​
​Thanks. I was thinking you were still talking about "populate" variants
of the functions and missed that you switched to the "to" variant in the
final example.
​

> Perhaps it'd be worth emphasizing the usefulness of jsonb_to_record[set]
> a bit more, say with examples in section 8.14.
>

A section titled "JSON Element Extraction" under 8.14 that covers those
functions in context and discusses the dynamics of multiple columns of ->
invocations seem worthwhile.

"Ideally, JSON documents should each represent an atomic datum that
business rules dictate cannot reasonably be further subdivided into smaller
datums that could be modified independently."

See that new section should you decide to not heed the above advice, and in
general converting between json and table forms.

David J.