Re: Why are JSON extraction functions STABLE and not IMMUTABLE?

On 2013-04-15 11:31:39 -0400, Andrew Dunstan wrote:
>
> On 04/15/2013 11:16 AM, hubert depesz lubaczewski wrote:
> >In current 9.3, I see:
> >
> >$ select p.proname, p.provolatile from pg_proc p join pg_namespace n on p.pronamespace = n.oid where n.nspname = 'pg_catalog' and p.proname ~ 'json';
> > proname | provolatile
> >---------------------------+-------------
> > json_in | s
> > json_out | i
> > json_recv | s
> > json_send | s
> > array_to_json | s
> > array_to_json | s
> > row_to_json | s
> > row_to_json | s
> > json_agg_transfn | i
> > json_agg_finalfn | i
> > json_agg | i
> > to_json | s
> > json_object_field | s
> > json_object_field_text | s
> > json_array_element | s
> > json_array_element_text | s
> > json_extract_path | s
> > json_extract_path_op | s
> > json_extract_path_text | s
> > json_extract_path_text_op | s
> > json_array_elements | s
> > json_array_length | s
> > json_object_keys | s
> > json_each | s
> > json_each_text | s
> > json_populate_record | s
> > json_populate_recordset | s
> >(27 rows)
> >
> >Is there any particular reason extract functions
> >(object_field/array_element/...) can't be immutable?
> >
> >I can't readily imagine a situation where output of these functions would
> >change for different queries.
> >
>
> Me either. It's an oversight, really. Unless there is any objection I'll
> change them toot sweet. What about the existing (as of 9.2) functions?

ISTM json_in, out, recv, send should also be immutable. array_to_json,
row_to_json et all can't be tho.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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