[feature] Issue#26 ADD NEW HANDLER METHODS FOR NOTIFYING STORAGE ENGI…

…NE OF IMMINENT INDEX Description: ------------ Ported from percona server: http://bazaar.launchpad.net/~laurynas-biveinis/percona-server/tokudb-prepare-scans/revision/566
xingchaoet · Oct 8, 2016 · 96ee8f5 · 96ee8f5
1 parent cf5e15e
commit 96ee8f5
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Showing 4 changed files with 71 additions and 2 deletions.
diff --git a/sql/handler.h b/sql/handler.h
@@ -2310,6 +2310,43 @@ class handler :public Sql_alloc
     uint key_len= calculate_key_len(table, active_index, key, keypart_map);
     return index_read_last(buf, key, key_len);
   }
+public:
+ /**
+    TokuDB:
+    Notify storage engine about imminent index scan where a large number of
+    rows is expected to be returned. Does not replace nor call index_init.
+  */
+  virtual int prepare_index_scan(void) { return 0; }
+
+  /**
+    Notify storage engine about imminent index range scan.
+  */
+  virtual int prepare_range_scan(const key_range *start_key,
+                                 const key_range *end_key)
+  {
+    return 0;
+  }
+
+  /**
+    Notify storage engine about imminent index read with a bitmap of used key
+    parts.
+  */
+  int prepare_index_key_scan_map(const uchar *key, key_part_map keypart_map)
+  {
+    uint key_len= calculate_key_len(table, active_index, key, keypart_map);
+    return prepare_index_key_scan(key, key_len);
+  }
+
+protected:
+
+  /**
+    Notify storage engine about imminent index read with key length.
+  */
+  virtual int prepare_index_key_scan(const uchar *key, uint key_len)
+  {
+    return 0;
+  }
+
 public:
   virtual int read_range_first(const key_range *start_key,
                                const key_range *end_key,

diff --git a/sql/opt_range.cc b/sql/opt_range.cc
@@ -10924,6 +10924,19 @@ int QUICK_SELECT_DESC::get_next()
       }
     }
 
+    /* TokuDB */
+    key_range prepare_range_start;
+    key_range prepare_range_end;
+
+    last_range->make_min_endpoint(&prepare_range_start);
+    last_range->make_max_endpoint(&prepare_range_end);
+    result= file->prepare_range_scan((last_range->flag & NO_MIN_RANGE)
+            ? NULL : &prepare_range_start,
+            (last_range->flag & NO_MAX_RANGE)
+            ? NULL : &prepare_range_end);
+    if (result)
+        DBUG_RETURN(result);
+
     if (last_range->flag & NO_MAX_RANGE)        // Read last record
     {
       int local_error;

diff --git a/sql/records.cc b/sql/records.cc
@@ -393,8 +393,14 @@ static int rr_quick(READ_RECORD *info)
 
 static int rr_index_first(READ_RECORD *info)
 {
-  int tmp= info->table->file->ha_index_first(info->record);
+  int tmp= info->table->file->prepare_index_scan();
   info->read_record= rr_index;
+  if (tmp)
+  {
+    tmp= rr_handle_error(info, tmp);
+    return tmp;
+  }
+  tmp= info->table->file->ha_index_first(info->record);
   if (tmp)
     tmp= rr_handle_error(info, tmp);
   return tmp;
@@ -416,8 +422,14 @@ 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->prepare_index_scan();
   info->read_record= rr_index_desc;
+  if (tmp)
+  {
+    tmp= rr_handle_error(info, tmp);
+    return tmp;
+  }
+  tmp= info->table->file->ha_index_last(info->record);
   if (tmp)
     tmp= rr_handle_error(info, tmp);
   return tmp;

diff --git a/sql/sql_executor.cc b/sql/sql_executor.cc
@@ -2210,6 +2210,9 @@ join_read_always_key(JOIN_TAB *tab)
 
   if (cp_buffer_from_ref(tab->join->thd, table, ref))
     return -1;
+  if ((error= table->file->prepare_index_key_scan_map(tab->ref.key_buff,
+                  make_prev_keypart_map(tab->ref.key_parts))))
+    return report_handler_error(table, error);
   if ((error= table->file->ha_index_read_map(table->record[0],
                                              tab->ref.key_buff,
                                              make_prev_keypart_map(tab->ref.key_parts),
@@ -2536,6 +2539,8 @@ join_read_first(JOIN_TAB *tab)
     (void) report_handler_error(table, error);
     return 1;
   }
+  if ((error= tab->table->file->prepare_index_scan()))
+    return 1;
   if ((error= tab->table->file->ha_index_first(tab->table->record[0])))
   {
     if (error != HA_ERR_KEY_NOT_FOUND && error != HA_ERR_END_OF_FILE)
@@ -2574,6 +2579,8 @@ join_read_last(JOIN_TAB *tab)
     (void) report_handler_error(table, error);
     return 1;
   }
+  if ((error= table->file->prepare_index_scan()))
+    return report_handler_error(table, error);
   if ((error= tab->table->file->ha_index_last(tab->table->record[0])))
     return report_handler_error(table, error);
   return 0;