executor: fix incorrect rows returned by TABLESAMPLE (#25357) (#25795)

pingcap · Jun 28, 2021 · 18d69e5 · 18d69e5
1 parent c8b2f25
commit 18d69e5
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Showing 2 changed files with 15 additions and 1 deletion.
diff --git a/executor/sample.go b/executor/sample.go
@@ -220,7 +220,7 @@ func splitIntoMultiRanges(store kv.Storage, startKey, endKey kv.Key) ([]kv.KeyRa
 		if kv.Key(start).Cmp(startKey) < 0 {
 			start = startKey
 		}
-		if kv.Key(end).Cmp(endKey) > 0 {
+		if end == nil || kv.Key(end).Cmp(endKey) > 0 {
 			end = endKey
 		}
 		ranges = append(ranges, kv.KeyRange{StartKey: start, EndKey: end})

diff --git a/executor/sample_test.go b/executor/sample_test.go
@@ -119,6 +119,20 @@ func (s *testTableSampleSuite) TestTableSampleMultiRegions(c *C) {
 	tk.MustExec("drop table t2;")
 }
 
+func (s *testTableSampleSuite) TestTableSampleNoSplitTable(c *C) {
+	tk := s.initSampleTest(c)
+	atomic.StoreUint32(&ddl.EnableSplitTableRegion, 0)
+	tk.MustExec("drop table if exists t1;")
+	tk.MustExec("drop table if exists t2;")
+	tk.MustExec("create table t1 (id int primary key);")
+	tk.MustExec("create table t2 (id int primary key);")
+	tk.MustExec("insert into t2 values(1);")
+	rows := tk.MustQuery("select * from t1 tablesample regions();").Rows()
+	rows2 := tk.MustQuery("select * from t2 tablesample regions();").Rows()
+	c.Assert(len(rows), Equals, 0)
+	c.Assert(len(rows2), Equals, 1)
+}
+
 func (s *testTableSampleSuite) TestTableSampleSchema(c *C) {
 	tk := s.initSampleTest(c)
 	tk.Se.GetSessionVars().EnableClusteredIndex = variable.ClusteredIndexDefModeOn