Skip first state change of EXCHANGE Partition.

dbms/src/TiDB/Schema/SchemaBuilder.cpp

@@ -98,6 +98,24 @@ void SchemaBuilder<Getter, NameMapper>::applyCreateTable(DatabaseID database_id,
 template <typename Getter, typename NameMapper>
 void SchemaBuilder<Getter, NameMapper>::applyExchangeTablePartition(const SchemaDiff & diff)
 {
+    if (diff.old_table_id == diff.table_id && diff.old_schema_id == diff.schema_id)
+    {
+        // Only internal changes in non-partitioned table, not affecting TiFlash
+        LOG_DEBUG(
+            log,
+            "Table is going to be exchanged, skipping for now. database_id={} table_id={}",
+            diff.schema_id,
+            diff.table_id);
+        return;
+    }
+    LOG_DEBUG(
+        log,
+        "Table and partition is exchanged. database_id={} table_id={}, part_db_id={}, part_table_id={} partition_id={}",
+        diff.old_schema_id,
+        diff.old_table_id,
+        diff.affected_opts[0].schema_id,
+        diff.affected_opts[0].table_id,
+        diff.table_id);
     /// Table_id in diff is the partition id of which will be exchanged,
     /// Schema_id in diff is the non-partition table's schema id
     /// Old_table_id in diff is the non-partition table's table id

tests/_env.sh

@@ -33,7 +33,7 @@ fi
 export storage_server="127.0.0.1"
 
 # Server port for connecting
-export storage_port="9000"
+export storage_port=${storage_port:-9000}
 
 # Default database for scripts
 export storage_db="system"

tests/fullstack-test2/ddl/alter_exchange_partition.test

@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# enable this test after https://github.com/pingcap/tiflash/issues/7941 is fixed
-#RETURN
 
 >> DBGInvoke __enable_schema_sync_service('true')
 mysql> drop table if exists test.e;