MDEV-26345 [wip] Skip "auxiliary" fields in spider group by handler

Also, stop skipping const items, which causes failures in mdev_29502
and mdev_20502

sql/sql_select.h

@@ -1473,7 +1473,7 @@ class JOIN :public Sql_alloc
 
     Then, ORDER/GROUP BY and Window Function code add columns that need to
     be saved to be available in the post-group-by context. These extra columns
-    are added to the front, because this->all_fields points to the suffix of
+    are added to the front, because this->fields_list points to the suffix of
     this list.
   */
   List<Item> all_fields;

storage/spider/mysql-test/spider/bugfix/r/mdev_26345.result

+for master_1
+for child2
+for child3
+
+MDEV-26345 SELECT MIN on Spider table returns more rows than expected
+
+set spider_same_server_link= 1;
+CREATE SERVER srv FOREIGN DATA WRAPPER mysql
+OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+create table t2 (a int, b int, PRIMARY KEY (a, b));
+create table t1 (a int, b int, PRIMARY KEY (a, b)) ENGINE=Spider
+COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+insert into t1 VALUES (1,1), (1,2), (2,11);
+SELECT MIN(b), a FROM t1 WHERE a=1;
+MIN(b)	a
+1	1
+SELECT MAX(b), a FROM t1 WHERE a<3;
+MAX(b)	a
+11	1
+drop table t1, t2;
+create table t2 (a int, b int);
+create table t1 ENGINE=Spider
+COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+insert into t1 VALUES (1,1), (1,1), (2,2), (2,2);
+select distinct count(a) from t1 group by b;
+count(a)
+2
+drop table t1, t2;
+drop server srv;
+for master_1
+for child2
+for child3

storage/spider/mysql-test/spider/bugfix/t/mdev_26345.test

+--disable_warnings
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+--enable_warnings
+
+--echo
+--echo MDEV-26345 SELECT MIN on Spider table returns more rows than expected
+--echo
+
+set spider_same_server_link= 1;
+evalp CREATE SERVER srv FOREIGN DATA WRAPPER mysql
+OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+
+create table t2 (a int, b int, PRIMARY KEY (a, b));
+create table t1 (a int, b int, PRIMARY KEY (a, b)) ENGINE=Spider
+COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+
+insert into t1 VALUES (1,1), (1,2), (2,11);
+SELECT MIN(b), a FROM t1 WHERE a=1;
+SELECT MAX(b), a FROM t1 WHERE a<3;
+
+drop table t1, t2;
+
+create table t2 (a int, b int);
+create table t1 ENGINE=Spider
+COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+
+insert into t1 VALUES (1,1), (1,1), (2,2), (2,2);
+select distinct count(a) from t1 group by b;
+
+drop table t1, t2;
+
+drop server srv;
+
+--disable_warnings
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log
+--enable_warnings

storage/spider/mysql-test/spider/r/direct_join.result

@@ -76,7 +76,7 @@ a	b	c
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %';
 argument
-select t0.`b` `b`,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r` t0 join `auto_test_remote`.`ta_r_3` t1 join `auto_test_remote`.`ta_r_int` t2 where ((t0.`a` = t1.`a`) and (t2.`a` = t1.`a`)) order by t0.`b` desc limit 1,2
+select 1,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r` t0 join `auto_test_remote`.`ta_r_3` t1 join `auto_test_remote`.`ta_r_int` t2 where ((t0.`a` = t1.`a`) and (t2.`a` = t1.`a`)) order by t0.`b` desc limit 1,2
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %'
 SELECT a, b, date_format(c, '%Y-%m-%d %H:%i:%s') FROM ta_r ORDER BY a;
 a	b	date_format(c, '%Y-%m-%d %H:%i:%s')

storage/spider/mysql-test/spider/r/direct_join_using.result

@@ -79,7 +79,7 @@ a	b	c
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %';
 argument
-select t0.`b` `b`,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r` t0 join `auto_test_remote`.`ta_r_3` t1 join `auto_test_remote`.`ta_r_int` t2 where ((t0.`a` = t1.`a`) and (t2.`a` = t1.`a`)) order by t0.`b` desc
+select 1,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r` t0 join `auto_test_remote`.`ta_r_3` t1 join `auto_test_remote`.`ta_r_int` t2 where ((t0.`a` = t1.`a`) and (t2.`a` = t1.`a`)) order by t0.`b` desc
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %'
 SELECT a, b, date_format(c, '%Y-%m-%d %H:%i:%s') FROM ta_r ORDER BY a;
 a	b	date_format(c, '%Y-%m-%d %H:%i:%s')

storage/spider/mysql-test/spider/r/direct_left_join.result

@@ -79,7 +79,7 @@ a	b	c
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %';
 argument
-select t0.`b` `b`,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r` t0 left join `auto_test_remote`.`ta_r_3` t1 on (t1.`a` = t0.`a`) left join `auto_test_remote`.`ta_r_int` t2 on (t2.`a` = t0.`a`) where 1 order by t0.`b` desc
+select 1,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r` t0 left join `auto_test_remote`.`ta_r_3` t1 on (t1.`a` = t0.`a`) left join `auto_test_remote`.`ta_r_int` t2 on (t2.`a` = t0.`a`) where 1 order by t0.`b` desc
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %'
 SELECT a, b, date_format(c, '%Y-%m-%d %H:%i:%s') FROM ta_r ORDER BY a;
 a	b	date_format(c, '%Y-%m-%d %H:%i:%s')

storage/spider/mysql-test/spider/r/direct_right_join.result

@@ -79,7 +79,7 @@ a	b	c
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %';
 argument
-select t0.`b` `b`,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r_int` t2 left join (`auto_test_remote`.`ta_r_3` t1 join `auto_test_remote`.`ta_r` t0) on ((t0.`a` = t2.`a`) and (t1.`a` = t2.`a`)) where 1 order by t0.`b` desc
+select 1,t0.`a` `a`,t2.`b` `b`,t2.`c` `c` from `auto_test_remote`.`ta_r_int` t2 left join (`auto_test_remote`.`ta_r_3` t1 join `auto_test_remote`.`ta_r` t0) on ((t0.`a` = t2.`a`) and (t1.`a` = t2.`a`)) where 1 order by t0.`b` desc
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%select %'
 SELECT a, b, date_format(c, '%Y-%m-%d %H:%i:%s') FROM ta_r ORDER BY a;
 a	b	date_format(c, '%Y-%m-%d %H:%i:%s')

storage/spider/spd_db_mysql.cc

@@ -13971,14 +13971,19 @@ int spider_mbase_handler::append_list_item_select(
   Item *item;
   Field *field;
   const char *item_name;
+  uint skip= select->elements - fields->get_first_table_holder()->table->pos_in_table_list->select_lex->join->fields_list.elements;
   DBUG_ENTER("spider_mbase_handler::append_list_item_select");
   DBUG_PRINT("info",("spider this=%p", this));
   begin = str->length();
   while ((item = it++))
   {
-    if (item->const_item())
+    if (skip > 0)
     {
-      DBUG_PRINT("info",("spider const item"));
+      str->reserve(2);
+      str->q_append("1", 1);
+      field = *(fields->get_next_field_ptr());
+      str->q_append(SPIDER_SQL_COMMA_STR, SPIDER_SQL_COMMA_LEN);
+      skip--;
       continue;
     }
     if ((error_num = spider_db_print_item_type(item, NULL, spider, str,

storage/spider/spd_db_oracle.cc

@@ -12460,11 +12460,6 @@ int spider_oracle_handler::append_list_item_select(
   begin = str->length();
   while ((item = it++))
   {
-    if (item->const_item())
-    {
-      DBUG_PRINT("info",("spider const item"));
-      continue;
-    }
     if ((error_num = spider_db_print_item_type(item, NULL, spider, str,
       alias, alias_length, dbton_id, use_fields, fields)))
     {

storage/spider/spd_group_by_handler.cc

@@ -1547,11 +1547,6 @@ group_by_handler *spider_create_group_by_handler(
       while ((item = it++))
       {
         DBUG_PRINT("info",("spider select item=%p", item));
-        if (item->const_item())
-        {
-          DBUG_PRINT("info",("spider const item"));
-          continue;
-        }
         if (spider_db_print_item_type(item, NULL, spider, NULL, NULL, 0,
           roop_count, TRUE, fields_arg))
         {