Fix crash when distributed modify order by

Did not determine if order_by_ast is empty. If it is null, it will clone a null pointer and cause server crash.
ClickHouse · Mar 26, 2019 · 9d23277 · 9d23277
1 parent d448d3e
commit 9d23277
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Showing 3 changed files with 6 additions and 1 deletion.
diff --git a/dbms/src/Storages/AlterCommands.cpp b/dbms/src/Storages/AlterCommands.cpp
@@ -315,7 +315,7 @@ void AlterCommand::apply(ColumnsDescription & columns_description, IndicesDescri
     }
     else if (type == MODIFY_ORDER_BY)
     {
-        if (!primary_key_ast)
+        if (!primary_key_ast && order_by_ast)
         {
             /// Primary and sorting key become independent after this ALTER so we have to
             /// save the old ORDER BY expression as the new primary key.

diff --git a/dbms/tests/queries/0_stateless/00910_crash_when_distributed_modify_order_by.reference b/dbms/tests/queries/0_stateless/00910_crash_when_distributed_modify_order_by.reference
diff --git a/dbms/tests/queries/0_stateless/00910_crash_when_distributed_modify_order_by.sql b/dbms/tests/queries/0_stateless/00910_crash_when_distributed_modify_order_by.sql
@@ -0,0 +1,5 @@
+DROP TABLE IF EXISTS test.union1;
+DROP TABLE IF EXISTS test.union2;
+CREATE TABLE test.union1 ( date Date, a Int32, b Int32, c Int32, d Int32) ENGINE = MergeTree(date, (a, date), 8192);
+CREATE TABLE test.union2 ( date Date, a Int32, b Int32, c Int32, d Int32) ENGINE = Distributed(test_shard_localhost, 'test', 'union1');
+ALTER TABLE test.union2 MODIFY ORDER BY a; -- { serverError 48 }