diff --git a/sql/handler.h b/sql/handler.h
index f2cc50de38a..3e173905f66 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -1168,9 +1168,9 @@ void get_sweep_read_cost(TABLE *table, ha_rows nrows, bool interrupted,
                          COST_VECT *cost);
 
 /*
-  The below two are not used (and not handled) in this milestone of this WL
-  entry because there seems to be no use for them at this stage of
-  implementation.
+  Indicates that all scanned ranges will be singlepoint (aka equality) ranges.
+  The ranges may not use the full key but all of them will use the same number
+  of key parts.
 */
 #define HA_MRR_SINGLE_POINT 1
 #define HA_MRR_FIXED_KEY  2
@@ -1755,7 +1755,7 @@ public:
                                         uint key_parts, uint *bufsz, 
                                         uint *flags, COST_VECT *cost);
   virtual int multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                                    uint n_ranges, uint key_parts, uint mode,
+                                    uint n_ranges, uint mode, 
                                     HANDLER_BUFFER *buf);
   virtual int multi_range_read_next(char **range_info);
   virtual int read_range_first(const key_range *start_key,
diff --git a/sql/multi_range_read.cc b/sql/multi_range_read.cc
index 9c0a0233e0e..c86143c4a12 100644
--- a/sql/multi_range_read.cc
+++ b/sql/multi_range_read.cc
@@ -1,4 +1,5 @@
 #include "mysql_priv.h"
+#include <my_bit.h>
 #include "sql_select.h"
 
 /****************************************************************************
@@ -203,8 +204,7 @@ ha_rows handler::multi_range_read_info(uint keyno, uint n_ranges, uint n_rows,
 
 int
 handler::multi_range_read_init(RANGE_SEQ_IF *seq_funcs, void *seq_init_param,
-                               uint n_ranges, uint key_parts, uint mode, 
-                               HANDLER_BUFFER *buf)
+                               uint n_ranges, uint mode, HANDLER_BUFFER *buf)
 {
   DBUG_ENTER("handler::multi_range_read_init");
   mrr_iter= seq_funcs->init(seq_init_param, n_ranges, mode);
@@ -306,8 +306,7 @@ scan_it_again:
 */
 
 int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs, 
-                           void *seq_init_param, uint n_ranges, uint key_parts,
-                           uint mode,
+                           void *seq_init_param, uint n_ranges, uint mode,
                            HANDLER_BUFFER *buf)
 {
   uint elem_size;
@@ -324,8 +323,8 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
   {
     use_default_impl= TRUE;
     const int retval=
-      h->handler::multi_range_read_init(seq_funcs, seq_init_param,
-                                        n_ranges, key_parts, mode, buf);
+      h->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges, 
+                                        mode, buf);
     DBUG_RETURN(retval);
   }
   mrr_buf= buf->buffer;
@@ -337,51 +336,25 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
  
   mrr_buf_end= buf->buffer_end;
 
-
-  doing_cpk_scan= check_cpk_scan(h->active_index, mode); 
-  if (doing_cpk_scan)
+  if ((doing_cpk_scan= check_cpk_scan(h->active_index, mode)))
   {
-    /* 
-      When doing a scan on CPK, the buffer stores {lookup_tuple, range_id}
-      pairs 
-    */
-    uint keylen=0;
-    DBUG_ASSERT(key_parts != 0);
-    for (uint kp= 0; kp < key_parts; kp++)
-      keylen += table->key_info[h->active_index].key_part[kp].store_length;
-
-    cpk_tuple_length= keylen;
-    cpk_is_unique_scan= test(table->key_info[h->active_index].key_parts == 
-                             key_parts);
+    /* It's a DS-MRR/CPK scan */
+    cpk_tuple_length= 0; /* dummy value telling it needs to be inited */
     cpk_have_range= FALSE;
-    elem_size= keylen + (int)is_mrr_assoc * sizeof(void*);
     use_default_impl= FALSE;
-  }
-  else
-  {
-    /* In regular DS-MRR, buffer stores {rowid, range_id} pairs */
-    elem_size= h->ref_length + (int)is_mrr_assoc * sizeof(void*);
-  }
-
-  mrr_buf_last= mrr_buf + 
-                      ((mrr_buf_end - mrr_buf)/ elem_size)*
-                      elem_size;
-  mrr_buf_end= mrr_buf_last;
-
-  if (doing_cpk_scan)
-  {
-    /* 
-      DS-MRR/CPK: fill buffer with lookup tuples and sort; also we don't need a
-      secondary handler object.
-    */
     h->mrr_iter= seq_funcs->init(seq_init_param, n_ranges, mode);
     h->mrr_funcs= *seq_funcs;
     dsmrr_fill_buffer_cpk();
-    if (dsmrr_eof) 
+    if (dsmrr_eof)
       buf->end_of_used_area= mrr_buf_last;
     DBUG_RETURN(0); /* nothing could go wrong while filling the buffer */
   }
 
+  /* In regular DS-MRR, buffer stores {rowid, range_id} pairs */
+  elem_size= h->ref_length + (int)is_mrr_assoc * sizeof(void*);
+  mrr_buf_last= mrr_buf + ((mrr_buf_end - mrr_buf)/ elem_size)* elem_size;
+  mrr_buf_end= mrr_buf_last;
+
   /*
     There can be two cases:
     - This is the first call since index_init(), h2==NULL
@@ -454,8 +427,8 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
       goto error;
   }
 
-  if (h2->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges,
-                                         key_parts, mode, buf) || 
+  if (h2->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges, 
+                                         mode, buf) ||
       dsmrr_fill_buffer())
   {
     goto error;
@@ -604,6 +577,9 @@ int DsMrr_impl::key_tuple_cmp(void* arg, uchar* key1, uchar* key2)
 
 /*
   DS-MRR/CPK: Fill the buffer with (lookup_tuple, range_id) pairs and sort
+  
+  SYNOPSIS
+    DsMrr_impl::dsmrr_fill_buffer_cpk()
 
   DESCRIPTION
     DS-MRR/CPK: Fill the buffer with (lookup_tuple, range_id) pairs and sort
@@ -623,7 +599,18 @@ void DsMrr_impl::dsmrr_fill_buffer_cpk()
          !(res= h->mrr_funcs.next(h->mrr_iter, &cur_range)))
   {
     DBUG_ASSERT(cur_range.range_flag & EQ_RANGE);
-    DBUG_ASSERT(cpk_tuple_length == cur_range.start_key.length);
+    DBUG_ASSERT(!cpk_tuple_length || 
+                cpk_tuple_length == cur_range.start_key.length);
+    if (!cpk_tuple_length)
+    {
+      cpk_tuple_length= cur_range.start_key.length;
+      cpk_is_unique_scan= test(table->key_info[h->active_index].key_parts == 
+                               my_count_bits(cur_range.start_key.keypart_map));
+      uint elem_size= cpk_tuple_length + (int)is_mrr_assoc * sizeof(void*);
+      mrr_buf_last= mrr_buf + ((mrr_buf_end - mrr_buf)/elem_size) * elem_size;
+      mrr_buf_end= mrr_buf_last;
+    }
+
     /* Put key, or {key, range_id} pair into the buffer */
     memcpy(mrr_buf_cur, cur_range.start_key.key, cpk_tuple_length);
     mrr_buf_cur += cpk_tuple_length;
diff --git a/sql/multi_range_read.h b/sql/multi_range_read.h
index 5dd2e0d6adf..7a5e57e490e 100644
--- a/sql/multi_range_read.h
+++ b/sql/multi_range_read.h
@@ -87,8 +87,7 @@ public:
     table= table_arg;
   }
   int dsmrr_init(handler *h, RANGE_SEQ_IF *seq_funcs, void *seq_init_param, 
-                 uint n_ranges, uint key_parts, uint mode, 
-                 HANDLER_BUFFER *buf);
+                 uint n_ranges, uint mode, HANDLER_BUFFER *buf);
   void dsmrr_close();
   int dsmrr_next(char **range_info);
 
diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index 25c4259295f..ad0f9301b7f 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -8368,7 +8368,6 @@ int QUICK_RANGE_SELECT::reset()
  
   RANGE_SEQ_IF seq_funcs= {quick_range_seq_init, quick_range_seq_next, 0, 0};
   error= file->multi_range_read_init(&seq_funcs, (void*)this, ranges.elements,
-                                     uint(-1),
                                      mrr_flags, mrr_buf_desc? mrr_buf_desc: 
                                                               &empty_buf);
   DBUG_RETURN(error);
diff --git a/sql/sql_join_cache.cc b/sql/sql_join_cache.cc
index 120b109d8ff..c536026214c 100644
--- a/sql/sql_join_cache.cc
+++ b/sql/sql_join_cache.cc
@@ -2376,8 +2376,7 @@ JOIN_CACHE_BKA::init_join_matching_records(RANGE_SEQ_IF *seq_funcs, uint ranges)
   */ 
   if (!file->inited)
     file->ha_index_init(join_tab->ref.key, 1);
-  if ((error= file->multi_range_read_init(seq_funcs, (void*) this, ranges,
-					  join_tab->ref.key_parts,
+  if ((error= file->multi_range_read_init(seq_funcs, (void*) this, ranges, 
                                           mrr_mode, &mrr_buff)))
     rc= error < 0 ? NESTED_LOOP_NO_MORE_ROWS: NESTED_LOOP_ERROR;
   
diff --git a/storage/maria/ha_maria.cc b/storage/maria/ha_maria.cc
index 43c6cd6606a..e27983989d8 100644
--- a/storage/maria/ha_maria.cc
+++ b/storage/maria/ha_maria.cc
@@ -3501,11 +3501,10 @@ static SHOW_VAR status_variables[]= {
  ***************************************************************************/
 
 int ha_maria::multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                                     uint n_ranges, uint key_parts, uint mode, 
-                                     HANDLER_BUFFER *buf)
+                                    uint n_ranges, uint mode, 
+                                    HANDLER_BUFFER *buf)
 {
-  return ds_mrr.dsmrr_init(this, seq, seq_init_param, n_ranges, key_parts, 
-                           mode, buf);
+  return ds_mrr.dsmrr_init(this, seq, seq_init_param, n_ranges, mode, buf);
 }
 
 int ha_maria::multi_range_read_next(char **range_info)
diff --git a/storage/maria/ha_maria.h b/storage/maria/ha_maria.h
index 177008f422a..6901229bb44 100644
--- a/storage/maria/ha_maria.h
+++ b/storage/maria/ha_maria.h
@@ -174,8 +174,7 @@ public:
    * Multi Range Read interface
    */
   int multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                            uint n_ranges, uint key_parts, uint mode, 
-                            HANDLER_BUFFER *buf);
+                            uint n_ranges, uint mode, HANDLER_BUFFER *buf);
   int multi_range_read_next(char **range_info);
   ha_rows multi_range_read_info_const(uint keyno, RANGE_SEQ_IF *seq,
                                       void *seq_init_param, 
diff --git a/storage/myisam/ha_myisam.cc b/storage/myisam/ha_myisam.cc
index bb6ac446a4f..95ab5cb167e 100644
--- a/storage/myisam/ha_myisam.cc
+++ b/storage/myisam/ha_myisam.cc
@@ -2217,10 +2217,10 @@ static int myisam_init(void *p)
  ***************************************************************************/
 
 int ha_myisam::multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                                     uint n_ranges, uint key_parts, uint mode, 
+                                     uint n_ranges, uint mode, 
                                      HANDLER_BUFFER *buf)
 {
-  return ds_mrr.dsmrr_init(this, seq, seq_init_param, n_ranges, key_parts, mode, buf);
+  return ds_mrr.dsmrr_init(this, seq, seq_init_param, n_ranges, mode, buf);
 }
 
 int ha_myisam::multi_range_read_next(char **range_info)
diff --git a/storage/myisam/ha_myisam.h b/storage/myisam/ha_myisam.h
index d37870b861b..f5428e653c4 100644
--- a/storage/myisam/ha_myisam.h
+++ b/storage/myisam/ha_myisam.h
@@ -162,8 +162,7 @@ public:
    * Multi Range Read interface
    */
   int multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                            uint n_ranges, uint key_parts, uint mode, 
-                            HANDLER_BUFFER *buf);
+                            uint n_ranges, uint mode, HANDLER_BUFFER *buf);
   int multi_range_read_next(char **range_info);
   ha_rows multi_range_read_info_const(uint keyno, RANGE_SEQ_IF *seq,
                                       void *seq_init_param, 
diff --git a/storage/xtradb/handler/ha_innodb.cc b/storage/xtradb/handler/ha_innodb.cc
index a8ccb426aa5..8aff0103e20 100644
--- a/storage/xtradb/handler/ha_innodb.cc
+++ b/storage/xtradb/handler/ha_innodb.cc
@@ -11025,10 +11025,10 @@ test_innobase_convert_name()
  */
 
 int ha_innobase::multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                                       uint n_ranges, uint key_parts, uint mode,
+                                       uint n_ranges, uint mode, 
                                        HANDLER_BUFFER *buf)
 {
-  return ds_mrr.dsmrr_init(this, seq, seq_init_param, n_ranges, key_parts, mode, buf);
+  return ds_mrr.dsmrr_init(this, seq, seq_init_param, n_ranges, mode, buf);
 }
 
 int ha_innobase::multi_range_read_next(char **range_info)
diff --git a/storage/xtradb/handler/ha_innodb.h b/storage/xtradb/handler/ha_innodb.h
index 0c1f2b42dd6..41a073e4374 100644
--- a/storage/xtradb/handler/ha_innodb.h
+++ b/storage/xtradb/handler/ha_innodb.h
@@ -210,8 +210,7 @@ public:
    * Multi Range Read interface
    */
   int multi_range_read_init(RANGE_SEQ_IF *seq, void *seq_init_param,
-                            uint n_ranges, uint key_parts, uint mode, 
-                            HANDLER_BUFFER *buf);
+                            uint n_ranges, uint mode, HANDLER_BUFFER *buf);
   int multi_range_read_next(char **range_info);
   ha_rows multi_range_read_info_const(uint keyno, RANGE_SEQ_IF *seq,
                                       void *seq_init_param,