MDEV-16327: Server doesn't account for engines that supports OFFSET on their own.

Engine get LIMIT/OFFSET info an can it use/reset.

sql/group_by_handler.h

@@ -14,6 +14,10 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
 
+#ifndef GROUP_BY_HANDLER_INCLUDED
+#define GROUP_BY_HANDLER_INCLUDED
+
+class Select_limit_counters;
 /*
   This file implements the group_by_handler interface. This interface
   can be used by storage handlers that can intercept summary or GROUP
@@ -56,7 +60,7 @@ struct Query
   ORDER      *order_by;
   Item       *having;
   // LIMIT
-  //ha_rows select_limit_cnt, offset_limit_cnt;
+  Select_limit_counters *limit;
 };
 
 class group_by_handler
@@ -101,3 +105,4 @@ public:
   virtual void print_error(int error, myf errflag);
 };
 
+#endif //GROUP_BY_HANDLER_INCLUDED

sql/sql_limit.h

@@ -28,6 +28,10 @@ class Select_limit_counters
     Select_limit_counters():
        select_limit_cnt(0), offset_limit_cnt(0)
        {};
+    Select_limit_counters(Select_limit_counters &orig):
+       select_limit_cnt(orig.select_limit_cnt),
+       offset_limit_cnt(orig.offset_limit_cnt)
+       {};
 
    void set_limit(ha_rows limit, ha_rows offset)
    {
@@ -48,6 +52,8 @@ class Select_limit_counters
 
    bool is_unlimited()
    { return select_limit_cnt == HA_POS_ERROR; }
+   bool is_unrestricted()
+   { return select_limit_cnt == HA_POS_ERROR && offset_limit_cnt == 0; }
    void set_unlimited()
    { select_limit_cnt= HA_POS_ERROR; offset_limit_cnt= 0; }
 

sql/sql_select.cc

@@ -3146,7 +3146,8 @@ bool JOIN::make_aggr_tables_info()
     {
       /* Check if the storage engine can intercept the query */
       Query query= {&all_fields, select_distinct, tables_list, conds,
-                    group_list, order ? order : group_list, having};
+                    group_list, order ? order : group_list, having,
+                    &select_lex->master_unit()->lim};
       group_by_handler *gbh= ht->create_group_by(thd, &query);
 
       if (gbh)

storage/sequence/mysql-test/sequence/group_by.result

@@ -103,3 +103,33 @@ count(NULL)
 select count(NULL) from seq_1_to_3 limit 0;
 count(NULL)
 # End of 10.3 tests
+#
+# MDEV-16327: Server doesn't account for engines that supports
+# OFFSET on their own.
+#
+select count(NULL) from seq_1_to_3 limit 1;
+count(NULL)
+0
+explain format=json select count(NULL) from seq_1_to_3 limit 1;
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "table": {
+      "message": "Storage engine handles GROUP BY"
+    }
+  }
+}
+select count(NULL) from seq_1_to_3 limit 1 offset 1;
+count(NULL)
+explain format=json select count(NULL) from seq_1_to_3 limit 1 offset 1;
+EXPLAIN
+{
+  "query_block": {
+    "select_id": 1,
+    "table": {
+      "message": "Storage engine handles GROUP BY"
+    }
+  }
+}
+# End of 10.5 tests

storage/sequence/mysql-test/sequence/group_by.test

@@ -56,3 +56,15 @@ select count(NULL) from seq_1_to_3;
 select count(NULL) from seq_1_to_3 limit 0;
 
 --echo # End of 10.3 tests
+
+--echo #
+--echo # MDEV-16327: Server doesn't account for engines that supports
+--echo # OFFSET on their own.
+--echo #
+
+select count(NULL) from seq_1_to_3 limit 1;
+explain format=json select count(NULL) from seq_1_to_3 limit 1;
+select count(NULL) from seq_1_to_3 limit 1 offset 1;
+explain format=json select count(NULL) from seq_1_to_3 limit 1 offset 1;
+
+--echo # End of 10.5 tests

storage/sequence/sequence.cc

@@ -28,6 +28,7 @@
 #include <handler.h>
 #include <table.h>
 #include <field.h>
+#include <sql_limit.h>
 
 static handlerton *sequence_hton;
 
@@ -361,15 +362,21 @@ static int dummy_savepoint(handlerton *, THD *, void *) { return 0; }
 
 class ha_seq_group_by_handler: public group_by_handler
 {
+  Select_limit_counters limit;
   List<Item> *fields;
   TABLE_LIST *table_list;
   bool first_row;
 
 public:
   ha_seq_group_by_handler(THD *thd_arg, List<Item> *fields_arg,
-                          TABLE_LIST *table_list_arg)
+                          TABLE_LIST *table_list_arg,
-    : group_by_handler(thd_arg, sequence_hton), fields(fields_arg),
+                          Select_limit_counters *orig_lim)
-      table_list(table_list_arg) {}
+    : group_by_handler(thd_arg, sequence_hton),  limit(orig_lim[0]),
+      fields(fields_arg), table_list(table_list_arg)
+    {
+      // Reset limit because we are handling it now
+      orig_lim->set_unlimited();
+    }
   ~ha_seq_group_by_handler() {}
   int init_scan() { first_row= 1 ; return 0; }
   int next_row();
@@ -425,7 +432,8 @@ create_group_by_handler(THD *thd, Query *query)
   }
 
   /* Create handler and return it */
-  handler= new ha_seq_group_by_handler(thd, query->select, query->from);
+  handler= new ha_seq_group_by_handler(thd, query->select, query->from,
+                                       query->limit);
   return handler;
 }
 
@@ -440,7 +448,9 @@ int ha_seq_group_by_handler::next_row()
     Check if this is the first call to the function. If not, we have already
     returned all data.
   */
-  if (!first_row)
+  if (!first_row ||
+      limit.get_offset_limit() > 0 ||
+      limit.get_select_limit() == 0)
     DBUG_RETURN(HA_ERR_END_OF_FILE);
   first_row= 0;