HIR planning: Also cast element type after CastInt2VectorToArray

src/sql/src/plan/typeconv.rs

@@ -880,11 +880,31 @@ static VALID_CASTS: LazyLock<BTreeMap<(SqlScalarBaseType, SqlScalarBaseType), Ca
             }),
 
             // INT2VECTOR
-            (Int2Vector, Array) => Implicit: CastTemplate::new(|_ecx, _ccx, _from_type, _to_type| {
-                Some(|e: HirScalarExpr| {
-                    e.call_unary(UnaryFunc::CastInt2VectorToArray(
-                        func::CastInt2VectorToArray,
-                    ))
+            (Int2Vector, Array) => Implicit: CastTemplate::new(|ecx, ccx, _from_type, to_type| {
+                let inner_to_type = to_type.unwrap_array_element_type();
+                // Int2Vector elements are Int16, so if the target element type
+                // differs we need to also cast the array elements after the
+                // Int2Vector -> Array(Int16) conversion. (Postgres seems to do the same.)
+                let element_cast = if inner_to_type != &SqlScalarType::Int16 {
+                    let cast_expr = plan_hypothetical_cast(
+                        ecx, ccx, &SqlScalarType::Int16, inner_to_type
+                    )?;
+                    Some((to_type.clone(), cast_expr))
+                } else {
+                    None
+                };
+                Some(move |e: HirScalarExpr| {
+                    let arr = e.call_unary(
+                        UnaryFunc::CastInt2VectorToArray(func::CastInt2VectorToArray)
+                    );
+                    match element_cast {
+                        Some((return_ty, cast_expr)) => {
+                            arr.call_unary(CastArrayToArray(
+                                func::CastArrayToArray { return_ty, cast_expr: Box::new(cast_expr) }
+                            ))
+                        }
+                        None => arr,
+                    }
                 })
             }),
             (Int2Vector, String) => Explicit: CastInt2VectorToString(func::CastInt2VectorToString),

test/sqllogictest/int2vector.slt

@@ -161,3 +161,57 @@ SELECT x::text FROM t ORDER BY x::text DESC;
 ----
 1
 (empty)
+
+simple conn=mz_system,user=mz_system
+ALTER SYSTEM SET enable_alter_table_add_column = true
+----
+COMPLETE 0
+
+# Regression test for
+# https://github.com/MaterializeInc/database-issues/issues/10087 and
+# https://github.com/MaterializeInc/database-issues/issues/10088:
+# this used to panic with "Can't union types: Array(Float64) and Array(Int16)"
+# due to Int2Vector not being properly cast to the target array element type.
+
+statement ok
+CREATE  TABLE  t1(c0 FLOAT8[] , c1 INT2VECTOR DEFAULT '', c2 int);
+
+query T
+SELECT CASE WHEN c2 = 5 THEN c0 ELSE c1 END FROM t1;
+----
+
+query T multiline
+EXPLAIN OPTIMIZED PLAN FOR
+SELECT CASE WHEN c2 = 5 THEN c0 ELSE c1 END FROM t1;
+----
+Explained Query:
+  Project (#3)
+    Map (case when (#2{c2} = 5) then #0{c0} else arraytoarray(int2vectortoarray(#1{c1})) end)
+      ReadStorage materialize.public.t1
+
+Source materialize.public.t1
+
+Target cluster: quickstart
+
+EOF
+
+statement ok
+CREATE TABLE t0(c0 FLOAT8[], c1 INT2VECTOR DEFAULT '')
+
+statement error WHERE clause must have type boolean, not type double precision\[\]
+SELECT t0.c1 FROM t0 WHERE (CASE t0.c1 WHEN 'bZkESziLfXXL3G3YWk3j3FGvDHCwEkrTmYd9ANGvVBoF0J4Dpim3YrnbiF38bQo5HA3kxP4kz1F1V6DIgKdfsbDT' THEN t0.c0 ELSE t0.c1 END ) UNION ALL SELECT t0.c1 FROM t0 WHERE (NOT (CASE t0.c1 WHEN 'bZkESziLfXXL3G3YWk3j3FGvDHCwEkrTmYd9ANGvVBoF0J4Dpim3YrnbiF38bQo5HA3kxP4kz1F1V6DIgKdfsbDT' THEN t0.c0 ELSE t0.c1 END )) UNION ALL SELECT t0.c1 FROM t0 WHERE (((CASE t0.c1 WHEN 'bZkESziLfXXL3G3YWk3j3FGvDHCwEkrTmYd9ANGvVBoF0J4Dpim3YrnbiF38bQo5HA3kxP4kz1F1V6DIgKdfsbDT' THEN t0.c0 ELSE t0.c1 END )) IS NULL)
+
+statement ok
+CREATE  TABLE  t2(c0 INT DEFAULT '', c1 BPCHAR NOT NULL DEFAULT '');
+
+statement ok
+CREATE  TABLE  t3(c0 INT2VECTOR DEFAULT NULL, c1 INT8 LIST DEFAULT '');
+
+statement ok
+CREATE VIEW IF NOT EXISTS v0(c0) AS SELECT ARRAY[true,false,true] FROM t2, t3 HAVING (NOT NULL) LIMIT 670620142;
+
+statement ok
+ALTER TABLE t2 ADD COLUMN c2 OID;
+
+query error NATURAL/USING join column "c0" could not convert type int2vector to boolean\[\]
+SELECT t2.c2, t2.c0, v0.c0, t2.c1 FROM t2, v0 NATURAL FULL JOIN t3;