executor: merge overlapped ranges when build key ranges for indexJoin (#14596)

executor/builder.go

@@ -2215,10 +2215,26 @@ func buildKvRangesForIndexJoin(ctx sessionctx.Context, tableID, indexID int64, l
 		}
 		kvRanges = append(kvRanges, tmpKvRanges...)
 	}
-	// kvRanges don't overlap each other. So compare StartKey is enough.
+	// Sort and merge the overlapped ranges.
 	sort.Slice(kvRanges, func(i, j int) bool {
 		return bytes.Compare(kvRanges[i].StartKey, kvRanges[j].StartKey) < 0
 	})
+	if cwc != nil {
+		// If cwc is not nil, we need to merge the overlapped ranges here.
+		mergedKeyRanges := make([]kv.KeyRange, 0, len(kvRanges))
+		for i := range kvRanges {
+			if len(mergedKeyRanges) == 0 {
+				mergedKeyRanges = append(mergedKeyRanges, kvRanges[i])
+				continue
+			}
+			if bytes.Compare(kvRanges[i].StartKey, mergedKeyRanges[len(mergedKeyRanges)-1].EndKey) <= 0 {
+				mergedKeyRanges[len(mergedKeyRanges)-1].EndKey = kvRanges[i].EndKey
+			} else {
+				mergedKeyRanges = append(mergedKeyRanges, kvRanges[i])
+			}
+		}
+		return mergedKeyRanges, nil
+	}
 	return kvRanges, nil
 }
 

executor/index_lookup_join_test.go

@@ -168,3 +168,14 @@ func (s *testSuite2) TestIndexJoinPartitionTable(c *C) {
 	tk.MustExec("insert into t values(1, 27, 2)")
 	tk.MustQuery("SELECT /*+ TIDB_INLJ(t1) */ count(1) FROM t t1 INNER JOIN (SELECT a, max(c) AS c FROM t WHERE b = 27 AND a = 1 GROUP BY a) t2 ON t1.a = t2.a AND t1.c = t2.c WHERE t1.b = 27").Check(testkit.Rows("1"))
 }
+
+func (s *testSuite2) TestIndexJoinMultiCondition(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t1, t2")
+	tk.MustExec("create table t1(a int not null, b int not null, key idx_a_b(a,b))")
+	tk.MustExec("create table t2(a int not null, b int not null)")
+	tk.MustExec("insert into t1 values (0,1), (0,2), (0,3)")
+	tk.MustExec("insert into t2 values (0,1), (0,2), (0,3)")
+	tk.MustQuery("select /*+ TIDB_INLJ(t1) */ count(*) from t1, t2 where t1.a = t2.a and t1.b < t2.b").Check(testkit.Rows("3"))
+}