# Copyright Materialize, Inc. and contributors. All rights reserved.
#
# Use of this software is governed by the Business Source License
# included in the LICENSE file at the root of this repository.
#
# As of the Change Date specified in that file, in accordance with
# the Business Source License, use of this software will be governed
# by the Apache License, Version 2.0.

# Regression test for issues corrected by materialize#17808.

# The following query should not frustrate the system, although it did prior to
# the associated PR being merged. It should produce an empty result set.
query I
with mutually recursive
    a(x int) as (select * from a)
select * from a;
----


statement ok
CREATE TABLE foo (a int)

# The following query should not inline `a` into `c`, as doing so would change
# the reference to `b` from "the prior iterate" to "the current iterate", at which
# point it could be canceled out, which would be incorrect.
# This query may need to be improved as `with mutually recursive` analysis improves,
# as it is not semantically complicated just syntactically complicated.
query T multiline
EXPLAIN OPTIMIZED PLAN WITH (humanized expressions) AS VERBOSE TEXT FOR with mutually recursive
    a(x int) as (select * from b),
    b(x int) as (select * from foo),
    -- meant to contain `b` minus its previous iterate.
    c(x int) as (select * from b except all select * from a)
select * from c;
----
Explained Query:
  With Mutually Recursive
    cte l0 =
      Get l1
    cte l1 =
      ReadStorage materialize.public.foo
  Return
    Threshold
      Union
        ReadStorage materialize.public.foo
        Negate
          Get l0

Source materialize.public.foo

Target cluster: quickstart

EOF