statistics: drop stats should delete topn

executor/simple_test.go

@@ -587,6 +587,42 @@ func (s *testSuite3) TestDropStats(c *C) {
 	h.SetLease(0)
 }
 
+func (s *testSuite3) TestDropStatsFromKV(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (c1 varchar(20), c2 varchar(20))")
+	tk.MustExec(`insert into t values("1","1"),("2","2"),("3","3"),("4","4")`)
+	tk.MustExec("insert into t select * from t")
+	tk.MustExec("insert into t select * from t")
+	tk.MustExec("analyze table t")
+	tblID := tk.MustQuery(`select tidb_table_id from information_schema.tables where table_name = "t" and table_schema = "test"`).Rows()[0][0].(string)
+	tk.MustQuery("select modify_count, count from mysql.stats_meta where table_id = " + tblID).Check(
+		testkit.Rows("0 16"))
+	tk.MustQuery("select hist_id from mysql.stats_histograms where table_id = " + tblID).Check(
+		testkit.Rows("1", "2"))
+	tk.MustQuery("select hist_id, bucket_id from mysql.stats_buckets where table_id = " + tblID).Check(
+		testkit.Rows("1 0",
+			"1 1",
+			"1 2",
+			"1 3",
+			"2 0",
+			"2 1",
+			"2 2",
+			"2 3"))
+	tk.MustQuery("select hist_id from mysql.stats_top_n where table_id = " + tblID).Check(
+		testkit.Rows("1", "1", "1", "1", "2", "2", "2", "2"))
+
+	tk.MustExec("drop stats t")
+	tk.MustQuery("select modify_count, count from mysql.stats_meta where table_id = " + tblID).Check(
+		testkit.Rows("0 16"))
+	tk.MustQuery("select hist_id from mysql.stats_histograms where table_id = " + tblID).Check(
+		testkit.Rows())
+	tk.MustQuery("select hist_id, bucket_id from mysql.stats_buckets where table_id = " + tblID).Check(
+		testkit.Rows())
+	tk.MustQuery("select hist_id from mysql.stats_top_n where table_id = " + tblID).Check(
+		testkit.Rows())
+}
+
 func (s *testSuite3) TestFlushTables(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

statistics/handle/gc.go

@@ -141,10 +141,12 @@ func (h *Handle) DeleteTableStatsFromKV(physicalID int64) (err error) {
 		return errors.Trace(err)
 	}
 	startTS := txn.StartTS()
-	sqls := make([]string, 0, 3)
+	sqls := make([]string, 0, 5)
 	// We only update the version so that other tidb will know that this table is deleted.
 	sqls = append(sqls, fmt.Sprintf("update mysql.stats_meta set version = %d where table_id = %d ", startTS, physicalID))
 	sqls = append(sqls, fmt.Sprintf("delete from mysql.stats_histograms where table_id = %d", physicalID))
 	sqls = append(sqls, fmt.Sprintf("delete from mysql.stats_buckets where table_id = %d", physicalID))
+	sqls = append(sqls, fmt.Sprintf("delete from mysql.stats_top_n where table_id = %d", physicalID))
+	sqls = append(sqls, fmt.Sprintf("delete from mysql.stats_feedback where table_id = %d", physicalID))
 	return execSQLs(context.Background(), exec, sqls)
 }