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

From Peter Eisentraut
Subject Re: [HACKERS] [PATCH] Generic type subscripting
Date
Msg-id bb39cf19-744c-e320-3f3d-42dbe4af51bf@2ndquadrant.com
Whole thread Raw
In response to Re: [HACKERS] [PATCH] Generic type subscripting  (Arthur Zakirov <a.zakirov@postgrespro.ru>)
Responses Re: [HACKERS] [PATCH] Generic type subscripting  (Arthur Zakirov <a.zakirov@postgrespro.ru>)
List pgsql-hackers
On 9/20/17 04:12, Arthur Zakirov wrote:
> On Tue, Sep 19, 2017 at 09:01:57PM -0400, Peter Eisentraut wrote:
>> Would you mind posting a summary of how you go here?
> 
> There were several points here to me:
> - it is necessary to solve the dependency problem (it can be solved also by adding several oid fields to the
pg_type)

A few oid or regproc fields in pg_type seem sensible.

> - users may want to add subscripting to their existing type, which already created in their database, or drop
subscriptingfrom existing type (it cannot be done by CREATE TYPE)
 

That's what ALTER TYPE is for.

> - other type related functionalities have their CREATE command and system catalog table. For example, CREATE CAST,
CREATETRANSFORM (this is a weakest point I think, mostly because of several casts and transforms can be defined to one
type,and only one subscripting can be defined to one type).
 

The difference is that those create associations between two separate
objects (cast: type1 <-> type2, transform: type <-> language).  A
subscripting is just a property of a type.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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