fix(tianmu): fix Load DPN when the table is empty (#964)

mysql-test/suite/tianmu/r/issue964.result

@@ -0,0 +1,28 @@
+USE test;
+DROP TABLE IF EXISTS t1,t2;
+CREATE TABLE `t1` (
+`id` int(11) DEFAULT NULL,
+`name` varchar(20) DEFAULT NULL,
+KEY `idx_n` (`name`)
+) DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
+CREATE TABLE `t2` (
+`id` int(11) DEFAULT NULL,
+`name` varchar(20) DEFAULT NULL,
+KEY `idx_n` (`name`)
+)DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
+insert into t1 values(1,'abc');
+insert into t1 values(2,'def');
+SELECT
+t1.id,
+t1.name,
+t2.id,
+t2.name
+FROM
+t1
+LEFT JOIN t2 ON
+t1.name = t2.name
+WHERE
+t1.name IN ('abc');
+id	name	id	name
+1	abc	NULL	NULL
+DROP TABLE t1,t2;

mysql-test/suite/tianmu/t/issue964.test

@@ -0,0 +1,44 @@
+--source include/have_tianmu.inc
+
+USE test;
+
+--disable_warnings
+
+DROP TABLE IF EXISTS t1,t2;
+
+## DDL
+
+CREATE TABLE `t1` (
+  `id` int(11) DEFAULT NULL,
+  `name` varchar(20) DEFAULT NULL,
+  KEY `idx_n` (`name`)
+) DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
+
+CREATE TABLE `t2` (
+  `id` int(11) DEFAULT NULL,
+  `name` varchar(20) DEFAULT NULL,
+  KEY `idx_n` (`name`)
+)DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
+
+## insert data, only for table t1
+
+insert into t1 values(1,'abc');
+insert into t1 values(2,'def');
+
+## join return empty table t2
+
+SELECT
+	t1.id,
+	t1.name,
+	t2.id,
+	t2.name
+FROM
+	t1
+LEFT JOIN t2 ON
+	t1.name = t2.name
+WHERE
+	t1.name IN ('abc');
+
+## clear tables
+
+DROP TABLE t1,t2;