Horton

Re: [PATCH] Generic type subscription

Aleksander Alekseev <a.alekseev@postgrespro.ru>

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From: Aleksander Alekseev <a.alekseev@postgrespro.ru>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Victor Wagner <vitus@wagner.pp.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2016-11-15T08:03:24Z
Lists: pgsql-hackers 
Hello.

I took a look on the latest -v4 patch. I would like to note that this
patch breaks a backward compatibility. For instance sr_plan extension[1]
stop to compile with errors like:

```
serialize.c:38:2: error: unknown type name ‘ArrayRef’
  JsonbValue *ArrayRef_ser(const ArrayRef *node, JsonbParseState *state,
bool sub_object);
  ^
serialize.c:913:2: error: unknown type name ‘ArrayRef’
  JsonbValue *ArrayRef_ser(const ArrayRef *node, JsonbParseState *state,
bool sub_object)
  ^
In file included from sr_plan.h:4:0,
                 from serialize.c:1:

...

```

Other extensions could be affected as well. I'm not saying that it's a
fatal drawback, but it's definitely something you should be aware of.

I personally strongly believe that we shouldn't break extensions between
major releases or at least make it trivial to properly rewrite them.
Unfortunately it's not a case currently.

[1] https://github.com/postgrespro/sr_plan

-- 
Best regards,
Aleksander Alekseev

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. Support subscripting of arbitrary types, not only arrays.

  5. Remove obsoleted code relating to targetlist SRF evaluation.

  6. Include <sys/select.h> where needed