Merge pull request #10870 from azat/fix-SIGSEGV-in-hash-table-for-string

alexey-milovidov · web-flow · commit 0433d9c6fc39 · 2020-05-13T18:40:28.000+03:00
Fix SIGSEGV in StringHashTable (if such key does not exist)
diff --git a/src/Common/HashTable/StringHashTable.h b/src/Common/HashTable/StringHashTable.h
@@ -333,7 +333,11 @@ class StringHashTable : private boost::noncopyable
         template <typename Submap, typename SubmapKey>
         auto ALWAYS_INLINE operator()(Submap & map, const SubmapKey & key, size_t hash)
         {
-            return &map.find(key, hash)->getMapped();
+            auto it = map.find(key, hash);
+            if (!it)
+                return decltype(&it->getMapped()){};
+            else
+                return &it->getMapped();
         }
     };
 
diff --git a/tests/queries/0_stateless/01279_dist_group_by.reference b/tests/queries/0_stateless/01279_dist_group_by.reference
diff --git a/tests/queries/0_stateless/01279_dist_group_by.sql b/tests/queries/0_stateless/01279_dist_group_by.sql
@@ -0,0 +1,9 @@
+drop table if exists data_01279;
+
+create table data_01279 (key String) Engine=TinyLog();
+insert into data_01279 select reinterpretAsString(number) from numbers(100000);
+
+set max_rows_to_group_by=10;
+set group_by_overflow_mode='any';
+set group_by_two_level_threshold=100;
+select * from data_01279 group by key format Null;

Original file line number	Diff line number	Diff line change
`@@ -333,7 +333,11 @@ class StringHashTable : private boost::noncopyable`
`333`	`333`	`template <typename Submap, typename SubmapKey>`
`334`	`334`	`auto ALWAYS_INLINE operator()(Submap & map, const SubmapKey & key, size_t hash)`
`335`	`335`	`{`
`336`		`- return &map.find(key, hash)->getMapped();`
	`336`	`+ auto it = map.find(key, hash);`
	`337`	`+ if (!it)`
	`338`	`+ return decltype(&it->getMapped()){};`
	`339`	`+ else`
	`340`	`+ return &it->getMapped();`
`337`	`341`	`}`
`338`	`342`	`};`
`339`	`343`