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Re: [HACKERS] [PATCH] Generic type subscripting

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, Alexander Korotkov <aekorotkov@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, David Steele <david@pgmasters.net>, Nikita Glukhov <n.gluhov@postgrespro.ru>, Alvaro Herrera <alvherre@2ndquadrant.com>, David Fetter <david@fetter.org>, Thomas Munro <thomas.munro@gmail.com>, Oleksandr Shulgin <oleksandr.shulgin@zalando.de>, Robert Haas <robertmhaas@gmail.com>, Michael Paquier <michael.paquier@gmail.com>, Oleg Bartunov <obartunov@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-12-31T19:21:55Z
Lists: pgsql-hackers 
čt 31. 12. 2020 v 15:27 odesílatel Dmitry Dolgov <9erthalion6@gmail.com>
napsal:

> > On Wed, Dec 30, 2020 at 09:01:37PM +0100, Dmitry Dolgov wrote:
> > > make check fails
> >
> > Yeah, apparently I forgot to enable asserts back after the last
> > benchmarking discussion, and missed some of those. Will fix.
> >
> > > 2. The index position was ignored.
> > >
> > > postgres=# update foo set a['a'][10] = '20';
> > > UPDATE 1
> > > postgres=# select * from foo;
> > > ┌─────────────┐
> > > │      a      │
> > > ╞═════════════╡
> > > │ {"a": [20]} │
> > > └─────────────┘
> > > (1 row)
> >
> > I just realized I haven't included "filling the gaps" part, that's why
> > it works as before. Can add this too.
> >
> > > 1. quietly ignored update
> > >
> > > postgres=# update foo set a['a'][10] = '20';
> > > UPDATE 1
> > > postgres=# select * from foo;
> > > ┌────┐
> > > │ a  │
> > > ╞════╡
> > > │ {} │
> > > └────┘
> > > (1 row)
> >
> > This belongs to the original jsonb_set implementation. Although if we
> > started to change it anyway with "filling the gaps", maybe it's fine to
> > add one more flag to tune its behaviour in this case as well. I can
> > check how complicated that could be.
>
> Here is what I had in mind. Assert issue in main patch is fixed (nothing
> serious, it was just the rawscalar check for an empty jsonb created
> during assignment), and the second patch contains all the bits with
> "filling the gaps" including your suggestion about creating the whole
> path if it's not present. The latter (creating the chain of empty
> objects) I haven't tested that much, but if there are any issues or
> concerns I guess it will not prevent the main patch from going forward


the tests passed and filling gaps works well

but creating empty objects doesn't work

create table foo(a jsonb);

insert into foo values('{}');

postgres=# update foo set a['k'][1] = '20';
UPDATE 1
postgres=# select * from foo;
┌───────────────────┐
│         a         │
╞═══════════════════╡
│ {"k": [null, 20]} │
└───────────────────┘
(1 row)

it is ok

postgres=# update foo set a['k3'][10] = '20';
UPDATE 1
postgres=# select * from foo;
┌───────────────────┐
│         a         │
╞═══════════════════╡
│ {"k": [null, 20]} │
└───────────────────┘
(1 row)

the second update was not successful



.
>

Commits

  1. Throw error when assigning jsonb scalar instead of a composite object

  2. Filling array gaps during jsonb subscripting

  3. Implementation of subscripting for jsonb

  4. Allow ALTER TYPE to update an existing type's typsubscript value.

  5. Allow subscripting of hstore values.

  6. Support subscripting of arbitrary types, not only arrays.

  7. jit: Reference function pointer types via llvmjit_types.c.

  8. Teach contain_leaked_vars that assignment SubscriptingRefs are leaky.

  9. jit: Correct parameter type for generated expression evaluation functions.

  10. Renaming for new subscripting mechanism

  11. Fix assertion failure for SSL connections.

  12. Teach eval_const_expressions() to handle some more cases.