Re: [PATCH] Allow multiple recursive self-references

 > On 14. Jan 2022, at 13:21, Peter Eisentraut 
<peter.eisentraut@enterprisedb.com> wrote:
 >
 > There is nothing in there that says that certain branches of the 
UNION in a recursive query mean certain things. In fact, it doesn't even 
require the query to contain a UNION at all.  It just says to iterate on 
evaluating the query until a fixed point is reached.  I think this 
supports my claim that the associativity and commutativity of a UNION in 
a recursive query still apply.
 >
 > This is all very complicated, so I don't claim this to be 
authoritative, but I just don't see anything in the spec that supports 
what you are saying.

Please also have a look at SQL:2016, 7.16 <query expression> General 
Rules 2) c),
which defines the evaluation semantics of recursive queries. I think 
that this part
of the SQL standard refutes your argument.

Best,
   -- Denis