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Re: [HACKERS] [PATCH] Generic type subscripting - Mailing list pgsql-hackers

From Dmitry Dolgov
Subject Re: [HACKERS] [PATCH] Generic type subscripting
Date
Msg-id CA+q6zcUaOE=fVTEZrZ_sB2bC+fJEnAe5MkeZpv8VFJJWmiHXaw@mail.gmail.com
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In response to Re: [HACKERS] [PATCH] Generic type subscripting  (Arthur Zakirov <a.zakirov@postgrespro.ru>)
Responses Re: [HACKERS] [PATCH] Generic type subscripting
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> On 13 November 2017 at 14:11, Arthur Zakirov <a.zakirov@postgrespro.ru> wrote:
> > I have a little complain about how ExprEvalStep gets resvalue. resvalue is
> > assigned in one place (within ExecEvalSubscriptingRefFetch(),
> > ExecEvalSubscriptingRefAssign()), resnull is assigned in another place
> > (within jsonb_subscript_fetch(), jsonb_subscript_assign()).
>
> Hm...I'm afraid I don't get this. `resnull` is never assigned inside
> `jsonb_subscript_fetch` or `jsonb_subscript_assign`, instead it's coming
> from `ExecInterpExp` as `isnull` if I remember correctly. Are we talking
> about
> the same thing?
>
> No, I meant ExprEvalStep struct. For example, within
> ExecEvalSubscriptingRefFetch() you assign op->resvalue but op->resnull is
> leaved as unchanged

Oh, I see now, thanks for the explanation. Actually, it's how it was
implemented before in array subscripting, and I tried to be consistent with
this implementation. But now I wonder if `resnull` is really needed in
`jsonb_get_element`, `array_get_element` and it seems to me that I can even get
rid of it so, that everything would be assigned in `jsonb_subscript_fetch`,
`array_subscript_fetch` - I'll send a new version of the patch soon.

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