typos in comments, minor stylistic edits

sql/group_by_handler.cc

@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2014, SkySQL Ab & MariaDB Foundation
+   Copyright (c) 2014, 2015 SkySQL Ab & MariaDB Foundation
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,10 +21,6 @@
   upper level.
 */
 
-#ifdef USE_PRAGMA_IMPLEMENTATION
-#pragma implementation				// gcc: Class implementation
-#endif
-
 #include "sql_priv.h"
 #include "sql_select.h"
 
@@ -45,7 +41,7 @@ int group_by_handler::execute(JOIN *join)
   ha_rows max_limit;
   ha_rows *reset_limit= 0;
   Item **reset_item= 0;
-  DBUG_ENTER("group_by_handler");
+  DBUG_ENTER("group_by_handler::execute");
 
   if ((err= init_scan()))
     goto error;

sql/group_by_handler.h

@@ -1,5 +1,5 @@
 /*
-   Copyright (c) 2014, SkySQL Ab & MariaDB Foundation
+   Copyright (c) 2014, 2015 SkySQL Ab & MariaDB Foundation
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -28,8 +28,6 @@
   SELECT a,count(*) as sum FROM t1 where b > 10 group by a, order by sum;
   SELECT a,count(*) FROM t1,t2;
   SELECT a, (select sum(*) from t2 where t1.a=t2.a) from t2;
-
-  See https://mariadb.atlassian.net/browse/MDEV-6080 for more information.
 */
 
 class JOIN;
@@ -46,10 +44,6 @@ public:
   Item *where, *having;
   handlerton *ht;                 /* storage engine of this handler */
 
-  /*
-    Bit's of things the storage engine can do for this query.
-    Should be initialized on object creation.
-  */
   /* Temporary table where all results should be stored in record[0] */
   TABLE *table;
 
@@ -90,6 +84,8 @@ public:
   }
 
   /*
+    Bits of things the storage engine can do for this query.
+    Should be initialized on object creation.
     Result data is sorted by the storage engine according to order_by (if it
     exists) else according to the group_by.  If this is not specified,
     MariaDB will store the result set into the temporary table and sort the

sql/handler.h

@@ -1264,7 +1264,7 @@ struct handlerton
     the summary / group by query.
     If the storage engine can't do that, return NULL.
 
-    This is only called for SELECT's where all tables are from the same
+    The server guaranteeds that all tables in the list belong to this
     storage engine.
   */
   group_by_handler *(*create_group_by)(THD *thd, SELECT_LEX *select_lex,

sql/sql_select.cc

@@ -760,7 +760,7 @@ JOIN::prepare(Item ***rref_pointer_array,
   TABLE_LIST *tbl;
   List_iterator_fast<TABLE_LIST> li(select_lex->leaf_tables);
   /*
-    If all tables comes from the same storage engine, one_storge_engine will
+    If all tables comes from the same storage engine, one_storage_engine will
     be set to point to the handlerton of this engine.
   */
   one_storage_engine= 0;
@@ -1118,7 +1118,8 @@ JOIN::optimize_inner()
       conds && conds->walk(&Item::exists2in_processor, 0, (uchar *)thd))
     DBUG_RETURN(1);
   /*
-TODO: make view to decide if it is possible to write to WHERE directly or make Semi-Joins able to process ON condition if it is possible
+    TODO
+    make view to decide if it is possible to write to WHERE directly or make Semi-Joins able to process ON condition if it is possible
   for (TABLE_LIST *tbl= tables_list; tbl; tbl= tbl->next_local)
   {
     if (tbl->on_expr &&
@@ -1969,8 +1970,8 @@ TODO: make view to decide if it is possible to write to WHERE directly or make S
       }
       storage_handler_for_group_by->store_data_in_temp_table= need_tmp;
       /*
-        If there is not specified ORDER BY, we should sort things according
+        If no ORDER BY clause was specified explicitly, we should sort things
-        to the group_by
+        according to the group_by
       */
       if (!order)
         order= group_list;
@@ -17861,7 +17862,8 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
     /* Setup HAVING to work with fields in temporary table */
     join->set_items_ref_array(join->items1);
     /* The storage engine will take care of the group by query result */
-    DBUG_RETURN(join->storage_handler_for_group_by->execute(join));
+    int res= join->storage_handler_for_group_by->execute(join);
+    DBUG_RETURN(res);
   }
 
   if (table)

sql/sql_select.h

@@ -1011,6 +1011,11 @@ public:
   */
   uint     top_join_tab_count;
   uint	   send_group_parts;
+  /*
+    This counts how many times do_select() was invoked for this JOIN.
+    It's used to restrict Pushdown_query::execute() only to the first
+    do_select() invocation.
+  */
   uint     do_select_call_count;
   /*
     True if the query has GROUP BY.

storage/sequence/sequence.cc

@@ -462,7 +462,7 @@ int ha_seq_group_by_handler::next_row()
   List_iterator_fast<Item> it(*fields);
   Item_sum *item_sum;
   Sequence_share *seqs= ((ha_seq*) table_list->table->file)->seqs;
-  DBUG_ENTER("ha_seq_group_by_handler");
+  DBUG_ENTER("ha_seq_group_by_handler::next_row");
 
   /*
     Check if this is the first call to the function. If not, we have already