0dca5d68d7fixes#8153
```diff
/citus/src/test/regress/expected/multi_subquery_misc.out
-- should error out
SELECT sql_subquery_test(1,1);
-ERROR: could not create distributed plan
-DETAIL: Possibly this is caused by the use of parameters in SQL functions, which is not supported in Citus.
-HINT: Consider using PL/pgSQL functions instead.
-CONTEXT: SQL function "sql_subquery_test" statement 1
+ sql_subquery_test
+-------------------
+ 307
+(1 row)
+
```
PostgreSQL 18 changes planner behavior for inlining/parameter handling
in SQL functions (pg18 commit `0dca5d68d`). As a result, a query in
`multi_subquery_misc` that previously failed to create a distributed
plan now succeeds. This PR updates the regression **expected** file to
reflect the new outcome on PG18+.
### What changed
* Updated `src/test/regress/expected/multi_subquery_misc.out`:
* Replaced the previous error block:
```
ERROR: could not create distributed plan
DETAIL: Possibly this is caused by the use of parameters in SQL
functions, which is not supported in Citus.
HINT: Consider using PL/pgSQL functions instead.
CONTEXT: SQL function "sql_subquery_test" statement 1
```
* with the actual successful result on PG18+:
```
sql_subquery_test
--------------------------------------------
307
(1 row)
```
* **PG < 18:** Behavior remains unchanged; the test still errors on
older versions.
* **PG ≥ 18:** The call succeeds; the updated expected output matches
actual results.
similar PR: https://github.com/citusdata/citus/pull/8184
DESCRIPTION: Introduce a new check to push down a query including union
and outer join to fix#8091 .
In "SafeToPushdownUnionSubquery", we check if the distribution column of
the outer relation is in the target list.
PostgreSQL might remove some of the subqueries when they do not
contribute to the query result at all. Citus should not try to
access such subqueries during planning.
Distributed query planning for subquery pushdown is done on the original
query. This prevents the usage of external parameters on the execution.
To overcome this, we manually replace the parameters on the original
query.
Mehmet YILMAZ
eaydingol
Philip Dubé
Onder Kalaci
mehmet furkan şahin