Re: Patch to add support of "IF NOT EXISTS" to others "CREATE" statements

On 2013-06-12 14:29:59 -0300, Fabrízio de Royes Mello wrote:
> On Fri, May 24, 2013 at 12:22 PM, Fabrízio de Royes Mello <
> fabriziomello@gmail.com> wrote:
>
> > Hi all,
> >
> > I working in a patch to include support of "IF NOT EXISTS" into "CREATE"
> > statements that not have it yet.
> >
> > I started with "DefineStmt" section from "src/backend/parser/gram.y":
> > - CREATE AGGREGATE [ IF NOT EXISTS ] ...
> > - CREATE OPERATOR [ IF NOT EXISTS ] ...
> > - CREATE TYPE [ IF NOT EXISTS ] ... [AS [{ENUM | RANGE}] (...)]
> > - CREATE TEXT SEARCH {PARSER | DITIONARY | TEMPLATE | CONFIGURATION} [ IF
> > NOT EXISTS ] ...
> > - CREATE COLLATION [ IF NOT EXISTS ] ...
> >
> >
> The attached patch add support to "IF NOT EXISTS" to "CREATE" statements
> listed below:
>
> - CREATE AGGREGATE [ IF NOT EXISTS ] ...
> - CREATE CAST [ IF NOT EXISTS ] ...
> - CREATE COLLATION [ IF NOT EXISTS ] ...
> - CREATE OPERATOR [ IF NOT EXISTS ] ...
> - CREATE TEXT SEARCH {PARSER | DICTIONARY | TEMPLATE | CONFIGURATION} [ IF
> NOT EXISTS ] ...
> - CREATE TYPE [ IF NOT EXISTS ] ... [AS [{ENUM | RANGE}] (...)]

I'd argue if we go that way - which seems to be a good idea - we really
ought to make a complete pass and add it to all commands where it's
currently missing.

* CREATE DOMAIN
* CREATE GROUP
* CREATE TABLE AS
* CREATE MATERIALIZED VIEW
* CREATE SEQUENCE (we have ALTER but not CREATE?)
* CREATE TABLESPACE (arguably slightly harder)
* CREATE FOREIGN DATA WRAPPER
* CREATE SERVER
* CREATE DATABASE
* CREATE USER MAPPING
* CREATE TRIGGER
* CREATE EVENT TRIGGER
* CREATE INDEX
* CLUSTER

Cases that seem useful, even though we have OR REPLACE:
* CREATE VIEW
* CREATE FUNCTION

Of dubious use:
* CREATE OPERATOR CLASS
* CREATE OPERATOR FAMILY
* CREATE RULE
* CREATE CONVERSION

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services