System indexes are never unique indexes( was RE: [HACKERS] mdnblocks is an amazing time sink in huge relations)

> > 
> > After a thought,I propose the following solution.
> > 
> > 1. mdcreate() couldn't create existent relation files.
> >     If the existent file is of length zero,we would overwrite
> >     the file.(seems the comment in md.c says so but the
> >     code doesn't do so). 
> >     If the file is an Index relation file,we would overwrite
> >     the file.
> >
> 
> This may allow to CREATE TABLE simultaneously for the
> same table name. I would change to check the existence

As I was afraid,2 tables of a same name could be made.
After a short investigating,I found that system indexes are
never unique indexes.
Why ?
Without duplicate index check,it's very difficult to prevent
objects from having same name.

Comments ?

Hiroshi Inoue
Inoue@tpf.co.jp