executor: use deep copy for maxMin4JSON (#15242) (#15288)

pingcap · Mar 13, 2020 · 8fca74f · 8fca74f
1 parent 78d1a93
commit 8fca74f
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Showing 2 changed files with 15 additions and 1 deletion.
diff --git a/executor/aggfuncs/func_max_min.go b/executor/aggfuncs/func_max_min.go
@@ -633,7 +633,7 @@ func (e *maxMin4JSON) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup [
 		}
 		cmp := json.CompareBinary(input, p.val)
 		if e.isMax && cmp > 0 || !e.isMax && cmp < 0 {
-			p.val = input
+			p.val = input.Copy()
 		}
 	}
 	return nil

diff --git a/executor/aggregate_test.go b/executor/aggregate_test.go
@@ -725,3 +725,17 @@ func (s *testSuite) TestIssue10608(c *C) {
 	tk.MustExec("INSERT INTO s VALUES (100292, 508931),(120002, 508932);")
 	tk.MustQuery("select (select group_concat(concat(123,'-')) from t where t.id = b group by t.id)  from s;").Check(testkit.Rows("123-", "123-"))
 }
+
+func (s *testSuite) TestPR15242ShallowCopy(c *C) {
+	tk := testkit.NewTestKitWithInit(c, s.store)
+	tk.MustExec(`drop table if exists t;`)
+	tk.MustExec(`create table t(a json);`)
+	tk.MustExec(`insert into t values ('{"id": 1,"score":23}');`)
+	tk.MustExec(`insert into t values ('{"id": 2,"score":23}');`)
+	tk.MustExec(`insert into t values ('{"id": 1,"score":233}');`)
+	tk.MustExec(`insert into t values ('{"id": 2,"score":233}');`)
+	tk.MustExec(`insert into t values ('{"id": 3,"score":233}');`)
+	tk.Se.GetSessionVars().MaxChunkSize = 2
+	tk.MustQuery(`select max(JSON_EXTRACT(a, '$.score')) as max_score,JSON_EXTRACT(a,'$.id') as id from t group by id order by id;`).Check(testkit.Rows("233 1", "233 2", "233 3"))
+
+}