Обсуждение: Possible Documentation Update for ALTER STATISTICS

Hi Ahmet,

On 11/4/21 14:35, Ahmet Gedemenli wrote:
> Hey,
> 
> I've noticed that the current documentation doesn't mention IF EXISTS 
> clause for ALTER STATISTICS in the synopsis section, where PG supports it.
> https://www.postgresql.org/docs/14/sql-alterstatistics.html 
> <https://www.postgresql.org/docs/14/sql-alterstatistics.html>
> (Only for the last item, that is ALTER STATISTICS .. SET STATISTICS; for 
> the others, PG just throws a syntax error.)
> 
> I'm from the Citus team and noticed this while bug fixing, and I wonder 
> if it is intentional or not. If it's intentionally supported while the 
> other ALTER STATISTICS statement types are not supported, it would be 
> good to mention that in the documentation.
> 

Well, it's intentional in the sense that support for IF EXISTS in ALTER 
commands is rather spotty. For OWNER TO it's not supported at all, and 
for the other (RENAME & SET SCHEMA) it's supported only for some object 
types. So we added the minimum grammar and never got around to add it.

So you're right we should update the docs for the SET STATISTICS case to 
show it's supported in 14. I'll do that shortly.

For 15+ we could improve this to allow IF EXISTS in the other cases. For 
RENAME and SET SCHEMA it's fairly easy (see attached fix), for OWNER TO 
it's going to be more work because the AlterOwnerStmt does not have the 
missing_ok flag.

regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company