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Re: Extract numeric filed in JSONB more effectively - Mailing list pgsql-hackers

From Pavel Stehule
Subject Re: Extract numeric filed in JSONB more effectively
Date
Msg-id CAFj8pRDbZCBgZhnOPK5JbMRDpUrpxceaGVaorz30PycAjteeig@mail.gmail.com
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In response to Re: Extract numeric filed in JSONB more effectively  (Andy Fan <zhihui.fan1213@gmail.com>)
Responses Re: Extract numeric filed in JSONB more effectively
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po 14. 8. 2023 v 9:06 odesílatel Andy Fan <zhihui.fan1213@gmail.com> napsal:

We'd still have functions like jsonb_field_as_numeric() under the
hood, but there's not an expectation that users call them explicitly.

To avoid the lots of functions like jsonb_field_as_int2/int4, I defined
Datum jsonb_object_field_type(.., Oid target_oid) at last,  so the
function must return "internal" or "anyelement".  Then we can see:

select jsonb_object_field_type(tb.a, 'a'::text, 1700) from tb;
ERROR:  cannot display a value of type anyelement.

you cannot to use type as parameter. There should be some typed value - like

jsonb_object_field, '{"a":10}', 'a', NULL::int)

and return type should be anyelement.

Another solution should be more deeper change like implementation of "coalesce"

 

The reason is clear to me, but  I'm not sure how to fix that or deserves
a fix? Or shall I define jsonb_object_field_int2/int8 to avoid this? 

This is an unresolved issue at the latest patch. 
--
Best Regards
Andy Fan

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