Re: [HACKERS] Efficient DELETE Strategies

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Hannu Krosing wrote:
>> What about
>> 
>> DELETE relation_expr FROM relation_expr [ , table_ref [ , ... ] ]
>> [ WHERE bool_expr ]
>> 
>> or
>> 
>> DELETE relation_expr.* FROM relation_expr [ , table_ref [ , ... ] ]
>> [ WHERE bool_expr ]

> So make the initial FROM optional and allow the later FROM to be a list
> of relations?  Seems kind of strange.

No, I think he's suggesting that one be able to pick out any element of
the FROM-list and say that that is the deletion target.  I really don't
want to get into that (unless there is precedent in Oracle or
someplace); it seems way too confusing to me.  It would also force us to
do error checking to eliminate cases that ought to just be syntactically
impossible: target table not present, target is a join or subselect
instead of a table, target is on wrong side of an outer join, etc.

[ and in another message ]
> The FROM ... FROM looks weird, and there is clearly confusion over the
> FROM t1, t2.  I wish there was another option.

The only other thing that's come to mind is to use a different keyword
(ie, not FROM) for the list of auxiliary relations.  WITH might work
from a simple readability point of view:
	DELETE FROM target WITH other-tables WHERE ...
But we've already got FROM as the equivalent construct in UPDATE, so it
seems weird to use something else in DELETE.

			regards, tom lane