Fix rdb_i_s_sst_props_fields_info (facebook#1267)

Summary:
In `rdb_i_s_sst_props_fields_info` definition, flag `MY_I_S_MAYBE_NULL`
is missing for fields `COMPRESSION_ALGO`, `FILTER_POLICY`,
`COMPRESSION_OPTIONS`, causing the `set_null` does not take effect,
these 3 fields will keep last SST's value.

This PR fixed this issue.

Pull Request resolved: facebook#1267

Reviewed By: lth

Differential Revision: D42928109

Pulled By: hermanlee

storage/rocksdb/rdb_i_s.cc

@@ -1398,16 +1398,18 @@ static ST_FIELD_INFO rdb_i_s_sst_props_fields_info[] = {
                        MYSQL_TYPE_LONGLONG, 0),
     ROCKSDB_FIELD_INFO("FILTER_BLOCK_SIZE", sizeof(int64_t),
                        MYSQL_TYPE_LONGLONG, 0),
-    ROCKSDB_FIELD_INFO("COMPRESSION_ALGO", NAME_LEN + 1, MYSQL_TYPE_STRING, 0),
+    ROCKSDB_FIELD_INFO("COMPRESSION_ALGO", NAME_LEN + 1, MYSQL_TYPE_STRING,
+                       MY_I_S_MAYBE_NULL),
     ROCKSDB_FIELD_INFO("CREATION_TIME", sizeof(int64_t), MYSQL_TYPE_LONGLONG,
                        0),
     ROCKSDB_FIELD_INFO("FILE_CREATION_TIME", sizeof(int64_t),
                        MYSQL_TYPE_LONGLONG, 0),
     ROCKSDB_FIELD_INFO("OLDEST_KEY_TIME", sizeof(int64_t), MYSQL_TYPE_LONGLONG,
                        0),
-    ROCKSDB_FIELD_INFO("FILTER_POLICY", NAME_LEN + 1, MYSQL_TYPE_STRING, 0),
+    ROCKSDB_FIELD_INFO("FILTER_POLICY", NAME_LEN + 1, MYSQL_TYPE_STRING,
+                       MY_I_S_MAYBE_NULL),
     ROCKSDB_FIELD_INFO("COMPRESSION_OPTIONS", NAME_LEN + 1, MYSQL_TYPE_STRING,
-                       0),
+                       MY_I_S_MAYBE_NULL),
     ROCKSDB_FIELD_INFO_END};
 
 static int rdb_i_s_sst_props_fill_table(
@@ -1476,6 +1478,7 @@ static int rdb_i_s_sst_props_fill_table(
       if (props.second->compression_name.empty()) {
         field[RDB_SST_PROPS_FIELD::COMPRESSION_ALGO]->set_null();
       } else {
+        field[RDB_SST_PROPS_FIELD::COMPRESSION_ALGO]->set_notnull();
         field[RDB_SST_PROPS_FIELD::COMPRESSION_ALGO]->store(
             props.second->compression_name.c_str(),
             props.second->compression_name.size(), system_charset_info);
@@ -1489,13 +1492,15 @@ static int rdb_i_s_sst_props_fill_table(
       if (props.second->filter_policy_name.empty()) {
         field[RDB_SST_PROPS_FIELD::FILTER_POLICY]->set_null();
       } else {
+        field[RDB_SST_PROPS_FIELD::FILTER_POLICY]->set_notnull();
         field[RDB_SST_PROPS_FIELD::FILTER_POLICY]->store(
             props.second->filter_policy_name.c_str(),
             props.second->filter_policy_name.size(), system_charset_info);
       }
       if (props.second->compression_options.empty()) {
         field[RDB_SST_PROPS_FIELD::COMPRESSION_OPTIONS]->set_null();
       } else {
+        field[RDB_SST_PROPS_FIELD::COMPRESSION_OPTIONS]->set_notnull();
         field[RDB_SST_PROPS_FIELD::COMPRESSION_OPTIONS]->store(
             props.second->compression_options.c_str(),
             props.second->compression_options.size(), system_charset_info);