Merge 'Invalidate prepared statements for views when their schema changes.' from Eliran Sinvani

When a base table changes and altered, so does the views that might
refer to the added column (which includes "SELECT *" views and also
views that might need to use this column for rows lifetime (virtual
columns).
However the query processor implementation for views change notification
was an empty function.
Since views are tables, the query processor needs to at least treat them
as such (and maybe in the future, do also some MV specific stuff).
This commit adds a call to `on_update_column_family` from within
`on_update_view`.
The side effect true to this date is that prepared statements for views
which changed due to a base table change will be invalidated.

Fixes https://github.com/scylladb/scylladb/issues/16392

This series also adds a test which fails without this fix and passes when the fix is applied.

Closes scylladb/scylladb#16897

* github.com:scylladb/scylladb:
  Add test for mv prepared statements invalidation on base alter
  query processor: treat view changes at least as table changes

cql3/query_processor.cc

@@ -1084,6 +1084,9 @@ void query_processor::migration_subscriber::on_update_aggregate(const sstring& k
 void query_processor::migration_subscriber::on_update_view(
         const sstring& ks_name,
         const sstring& view_name, bool columns_changed) {
+    // scylladb/scylladb#16392 - Materialized views are also tables so we need at least handle
+    // them as such when changed.
+    on_update_column_family(ks_name, view_name, columns_changed);
 }
 
 void query_processor::migration_subscriber::on_update_tablet_metadata() {

test/cql-pytest/test_materialized_view.py

@@ -808,3 +808,17 @@ def test_mv_with_only_primary_key_rows(scylla_only, cql, test_keyspace):
             nodetool.flush(cql, view)
             assert(set([row.id for row in cql.execute(f'SELECT id FROM {view}')]) == set([1, 2, 3]))
             # We now believe that empty value serialization/deserialization is correct
+
+# This test is regression testing added after fixing:
+# https://github.com/scylladb/scylladb/issues/16392 - the gist of the issue is that
+# prepared statements on views are not invalidated when the base table changes.
+def test_mv_prepared_statement_with_altered_base(cql, test_keyspace):
+    with new_test_table(cql, test_keyspace, 'id int PRIMARY KEY, v1 int') as base:
+        with new_materialized_view(cql, table=base, select='*', pk='id', where='id IS NOT NULL') as view:
+            base_query = cql.prepare(f"SELECT * FROM {base} WHERE id=?")
+            view_query = cql.prepare(f"SELECT * FROM {view} WHERE id=?")
+            cql.execute(f"INSERT INTO {base} (id,v1) VALUES (0,0)")
+            assert cql.execute(base_query,[0]) == cql.execute(view_query,[0])
+            cql.execute(f"ALTER TABLE {base} ADD (v2 int)")
+            cql.execute(f"INSERT INTO {base} (id,v1,v2) VALUES (1,1,1)")
+            assert list(cql.execute(base_query,[1])) == list(cql.execute(view_query,[1]))