MDEV-19698: Cleanup READ_RECORD::record

https://github.com/MariaDB/server/pull/777#issuecomment-496469366

sql/item_subselect.cc

@@ -3877,7 +3877,6 @@ int subselect_single_select_engine::exec()
               tab->save_read_record= tab->read_record.read_record_func;
               tab->read_record.read_record_func= rr_sequential;
               tab->read_first_record= read_first_record_seq;
-              tab->read_record.record= tab->table->record[0];
               tab->read_record.thd= join->thd;
               tab->read_record.ref_length= tab->table->file->ref_length;
               tab->read_record.unlock_row= rr_unlock_row;
@@ -3895,7 +3894,6 @@ int subselect_single_select_engine::exec()
     for (JOIN_TAB **ptab= changed_tabs; ptab != last_changed_tab; ptab++)
     {
       JOIN_TAB *tab= *ptab;
-      tab->read_record.record= 0;
       tab->read_record.ref_length= 0;
       tab->read_first_record= tab->save_read_first_record;
       tab->read_record.read_record_func= tab->save_read_record;

sql/records.cc

@@ -77,7 +77,6 @@ bool init_read_record_idx(READ_RECORD *info, THD *thd, TABLE *table,
   bzero((char*) info,sizeof(*info));
   info->thd= thd;
   info->table= table;
-  info->record= table->record[0];
   info->print_error= print_error;
   info->unlock_row= rr_unlock_row;
 
@@ -210,7 +209,6 @@ bool init_read_record(READ_RECORD *info,THD *thd, TABLE *table,
   else
   {
     empty_record(table);
-    info->record= table->record[0];
     info->ref_length= (uint)table->file->ref_length;
   }
   info->select=select;
@@ -393,7 +391,7 @@ static int rr_index_first(READ_RECORD *info)
     return tmp;
   }
 
-  tmp= info->table->file->ha_index_first(info->record);
+  tmp= info->table->file->ha_index_first(info->record());
   info->read_record_func= rr_index;
   if (tmp)
     tmp= rr_handle_error(info, tmp);
@@ -416,7 +414,7 @@ static int rr_index_first(READ_RECORD *info)
 
 static int rr_index_last(READ_RECORD *info)
 {
-  int tmp= info->table->file->ha_index_last(info->record);
+  int tmp= info->table->file->ha_index_last(info->record());
   info->read_record_func= rr_index_desc;
   if (tmp)
     tmp= rr_handle_error(info, tmp);
@@ -442,7 +440,7 @@ static int rr_index_last(READ_RECORD *info)
 
 static int rr_index(READ_RECORD *info)
 {
-  int tmp= info->table->file->ha_index_next(info->record);
+  int tmp= info->table->file->ha_index_next(info->record());
   if (tmp)
     tmp= rr_handle_error(info, tmp);
   return tmp;
@@ -467,7 +465,7 @@ static int rr_index(READ_RECORD *info)
 
 static int rr_index_desc(READ_RECORD *info)
 {
-  int tmp= info->table->file->ha_index_prev(info->record);
+  int tmp= info->table->file->ha_index_prev(info->record());
   if (tmp)
     tmp= rr_handle_error(info, tmp);
   return tmp;
@@ -477,7 +475,7 @@ static int rr_index_desc(READ_RECORD *info)
 int rr_sequential(READ_RECORD *info)
 {
   int tmp;
-  while ((tmp= info->table->file->ha_rnd_next(info->record)))
+  while ((tmp= info->table->file->ha_rnd_next(info->record())))
   {
     tmp= rr_handle_error(info, tmp);
     break;
@@ -493,7 +491,7 @@ static int rr_from_tempfile(READ_RECORD *info)
   {
     if (my_b_read(info->io_cache,info->ref_pos,info->ref_length))
       return -1;					/* End of file */
-    if (!(tmp= info->table->file->ha_rnd_pos(info->record,info->ref_pos)))
+    if (!(tmp= info->table->file->ha_rnd_pos(info->record(), info->ref_pos)))
       break;
     /* The following is extremely unlikely to happen */
     if (tmp == HA_ERR_KEY_NOT_FOUND)
@@ -543,7 +541,7 @@ int rr_from_pointers(READ_RECORD *info)
     cache_pos= info->cache_pos;
     info->cache_pos+= info->ref_length;
 
-    if (!(tmp= info->table->file->ha_rnd_pos(info->record,cache_pos)))
+    if (!(tmp= info->table->file->ha_rnd_pos(info->record(), cache_pos)))
       break;
 
     /* The following is extremely unlikely to happen */
@@ -638,7 +636,7 @@ static int rr_from_cache(READ_RECORD *info)
       else
       {
 	error=0;
-	memcpy(info->record,info->cache_pos,
+        memcpy(info->record(), info->cache_pos,
                (size_t) info->table->s->reclength);
       }
       info->cache_pos+=info->reclength;

sql/records.h

@@ -19,9 +19,10 @@
 #pragma interface                      /* gcc class implementation */
 #endif
 
+#include "table.h"
+
 struct st_join_table;
 class handler;
-struct TABLE;
 class THD;
 class SQL_SELECT;
 class Copy_field;
@@ -58,7 +59,6 @@ struct READ_RECORD
   SQL_SELECT *select;
   uint ref_length, reclength, rec_cache_size, error_offset;
   uchar *ref_pos;				/* pointer to form->refpos */
-  uchar *record;
   uchar *rec_buf;                /* to read field values  after filesort */
   uchar	*cache,*cache_pos,*cache_end,*read_positions;
   struct st_sort_addon_field *addon_field;     /* Pointer to the fields info */
@@ -67,6 +67,7 @@ struct READ_RECORD
   void    (*unpack)(struct st_sort_addon_field *, uchar *, uchar *);
 
   int read_record() { return read_record_func(this); }
+  uchar *record() const { return table->record[0]; }
 
   /* 
     SJ-Materialization runtime may need to read fields from the materialized

sql/sql_select.cc

@@ -20439,7 +20439,6 @@ join_read_first(JOIN_TAB *tab)
   tab->table->status=0;
   tab->read_record.read_record_func= join_read_next;
   tab->read_record.table=table;
-  tab->read_record.record=table->record[0];
   if (!table->file->inited)
     error= table->file->ha_index_init(tab->index, tab->sorted);
   if (likely(!error))
@@ -20459,7 +20458,7 @@ static int
 join_read_next(READ_RECORD *info)
 {
   int error;
-  if (unlikely((error= info->table->file->ha_index_next(info->record))))
+  if (unlikely((error= info->table->file->ha_index_next(info->record()))))
     return report_error(info->table, error);
 
   return 0;
@@ -20479,7 +20478,6 @@ join_read_last(JOIN_TAB *tab)
   tab->table->status=0;
   tab->read_record.read_record_func= join_read_prev;
   tab->read_record.table=table;
-  tab->read_record.record=table->record[0];
   if (!table->file->inited)
     error= table->file->ha_index_init(tab->index, 1);
   if (likely(!error))
@@ -20496,7 +20494,7 @@ static int
 join_read_prev(READ_RECORD *info)
 {
   int error;
-  if (unlikely((error= info->table->file->ha_index_prev(info->record))))
+  if (unlikely((error= info->table->file->ha_index_prev(info->record()))))
     return report_error(info->table, error);
   return 0;
 }
@@ -20526,7 +20524,7 @@ static int
 join_ft_read_next(READ_RECORD *info)
 {
   int error;
-  if (unlikely((error= info->table->file->ha_ft_read(info->table->record[0]))))
+  if (unlikely((error= info->table->file->ha_ft_read(info->record()))))
     return report_error(info->table, error);
   return 0;
 }

sql/sql_window.cc

@@ -898,7 +898,7 @@ class Table_read_cursor : public Rowid_seq_cursor
   {
     Rowid_seq_cursor::init(info);
     table= info->table;
-    record= info->record;
+    record= info->record();
   }
 
   virtual int fetch()