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

From Dmitry Dolgov
Subject Re: [HACKERS] [PATCH] Generic type subscripting
Date
Msg-id CA+q6zcUA2VafRppdoR=rouWW4t=80iS=r51Pz121xNNygDNgjg@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  (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>)
List pgsql-hackers
> On 20 September 2017 at 17:19, Arthur Zakirov <a.zakirov@postgrespro.ru> wrote:
> As a conclusion:
> * additional field are needed to pg_type for *_fetch and *_assign functions to solve dependency problem

One last thing that I need to clarify. Initially there was an idea to minimize
changes in `pg_type` - that's why I added only one column there that contains an
OID of main subscripting function (and everything else you should find out
inside it). But I have no objections about adding more columns if everyone is
ok with that. Basically pros and cons (marked as + and -):

one new column in `pg_type`:

* less intrusive (+)
* it's neccessary to make a dependency record between subscripting functions
  explicitly (-)

three new columns in `pg_type`:

* more intrusive (-)
* we can create a dependency record between subscripting functions
  simultaneously with a custom type creation (+)
* custom subscripting code does not need to resolve `fetch` and `assign`
  functions (+)

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