LAV-2759: Support ALTER TASK compute assignment properties (#3176)

* LAV-2759: support ALTER TASK compute assignment

Implement Snowflake-compatible SET/UNSET WAREHOUSE and managed initial warehouse size mutations, including state preservation, validation, persistence, projections, and replayable DDL. Cloud snapshots cover all documented sizes, reset, invalid inputs, identifier forms, transitions, and started/suspended tasks.

Co-authored-by: Sabir Akhadov <sabir.akhadov@localstack.cloud>
## Test matrix
WAREHOUSE quoted/unquoted identifiers x suspended transitions  ->  tests/queries/test_tasks.py::test_alter_task_warehouse_compute_assignment
WAREHOUSE omitted/default x SET/UNSET/replacement/replay  ->  tests/queries/test_tasks.py::test_alter_task_warehouse_compute_assignment
WAREHOUSE missing x error  ->  tests/queries/test_tasks.py::test_alter_task_compute_assignment_invalid_and_started
WAREHOUSE x started/suspended transitions  ->  tests/queries/test_tasks.py::test_alter_task_compute_assignment_invalid_and_started
managed size XSMALL..XXXLARGE x replacement/projections  ->  tests/queries/test_tasks.py::test_alter_task_managed_warehouse_sizes_and_reset
managed size lowercase x preserved normalization  ->  tests/queries/test_tasks.py::test_alter_task_managed_warehouse_sizes_and_reset
managed size reset/default/replay  ->  tests/queries/test_tasks.py::test_alter_task_managed_warehouse_sizes_and_reset
managed size empty/below/above boundary x error  ->  tests/queries/test_tasks.py::test_alter_task_compute_assignment_invalid_and_started
managed size on warehouse-backed task x error  ->  tests/queries/test_tasks.py::test_alter_task_compute_assignment_invalid_and_started

* LAV-2759: make task compute DDL replayable

Canonicalize unquoted warehouse assignments and quote case-sensitive warehouse names in GET_DDL. Cloud snapshots now cover distinct replacement warehouses, quoted identifiers, and replay of every managed-size DDL.\n\nSwept ALTER TASK compute assignment for identifier persistence and replay gaps; fixed unquoted folding and quoted DDL rendering; managed-size and reset paths are clean.\n\n## Test matrix\nWAREHOUSE unquoted lowercase x replacement/canonicalization  ->  tests/queries/test_tasks.py::test_alter_task_warehouse_compute_assignment\nWAREHOUSE quoted case-sensitive x replacement/projections/replay  ->  tests/queries/test_tasks.py::test_alter_task_warehouse_compute_assignment\nWAREHOUSE missing unquoted x canonical error  ->  tests/queries/test_tasks.py::test_alter_task_compute_assignment_invalid_and_started\nmanaged size XSMALL..XXXLARGE x projections/DDL/replay  ->  tests/queries/test_tasks.py::test_alter_task_managed_warehouse_sizes_and_reset\nmanaged size reset x projections/DDL/replay  ->  tests/queries/test_tasks.py::test_alter_task_managed_warehouse_sizes_and_reset

Co-authored-by: Sabir Akhadov <sabir.akhadov@localstack.cloud>

---------

Co-authored-by: spiral <spiral@localhost>
Co-authored-by: Sabir Akhadov <sabir.akhadov@localstack.cloud>

Author: 3 people

src/ast/mod.rs

@@ -15719,6 +15719,14 @@ pub enum AlterTaskAction {
     AddAfter(Vec<ObjectName>),
     /// `REMOVE AFTER <task> [, <task> ...]`
     RemoveAfter(Vec<ObjectName>),
+    /// `SET WAREHOUSE = <warehouse>`
+    SetWarehouse(ObjectName),
+    /// `UNSET WAREHOUSE`
+    UnsetWarehouse,
+    /// `SET USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE = '<size>'`
+    SetManagedWarehouseSize(String),
+    /// `UNSET USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE`
+    UnsetManagedWarehouseSize,
 }
 
 impl fmt::Display for AlterTaskAction {
@@ -15736,6 +15744,17 @@ impl fmt::Display for AlterTaskAction {
                 "REMOVE AFTER {}",
                 display_comma_separated(tasks)
             ),
+            AlterTaskAction::SetWarehouse(warehouse) => {
+                write!(f, "SET WAREHOUSE = {warehouse}")
+            }
+            AlterTaskAction::UnsetWarehouse => write!(f, "UNSET WAREHOUSE"),
+            AlterTaskAction::SetManagedWarehouseSize(size) => write!(
+                f,
+                "SET USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE = '{size}'"
+            ),
+            AlterTaskAction::UnsetManagedWarehouseSize => {
+                write!(f, "UNSET USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE")
+            }
         }
     }
 }

src/parser/mod.rs

@@ -12890,9 +12890,33 @@ impl<'a> Parser<'a> {
             AlterTaskAction::RemoveAfter(
                 self.parse_comma_separated(|parser| parser.parse_object_name(false))?,
             )
+        } else if self.parse_keyword(Keyword::SET) {
+            if self.parse_keyword(Keyword::WAREHOUSE) {
+                self.expect_token(&Token::Eq)?;
+                AlterTaskAction::SetWarehouse(self.parse_object_name(false)?)
+            } else if self.parse_keyword(Keyword::USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE) {
+                self.expect_token(&Token::Eq)?;
+                AlterTaskAction::SetManagedWarehouseSize(self.parse_literal_string()?)
+            } else {
+                return self.expected(
+                    "WAREHOUSE or USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE after ALTER TASK SET",
+                    self.peek_token(),
+                );
+            }
+        } else if self.parse_keyword(Keyword::UNSET) {
+            if self.parse_keyword(Keyword::WAREHOUSE) {
+                AlterTaskAction::UnsetWarehouse
+            } else if self.parse_keyword(Keyword::USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE) {
+                AlterTaskAction::UnsetManagedWarehouseSize
+            } else {
+                return self.expected(
+                    "WAREHOUSE or USER_TASK_MANAGED_INITIAL_WAREHOUSE_SIZE after ALTER TASK UNSET",
+                    self.peek_token(),
+                );
+            }
         } else {
             return self.expected(
-                "RESUME, SUSPEND, ADD AFTER, or REMOVE AFTER after ALTER TASK",
+                "RESUME, SUSPEND, ADD AFTER, REMOVE AFTER, SET, or UNSET after ALTER TASK",
                 self.peek_token(),
             );
         };