Merge

include/my_tree.h

@@ -31,6 +31,7 @@ extern "C" {
 #define tree_set_pointer(element,ptr) *((uchar **) (element+1))=((uchar*) (ptr))
 
 #define TREE_NO_DUPS 1
+#define TREE_ONLY_DUPS 2
 
 typedef enum { left_root_right, right_root_left } TREE_WALK;
 typedef uint32 element_count;

mysys/tree.c

@@ -221,6 +221,8 @@ TREE_ELEMENT *tree_insert(TREE *tree, void *key, uint key_size,
   }
   if (element == &tree->null_element)
   {
+    if (tree->flag & TREE_ONLY_DUPS)
+      return((TREE_ELEMENT *) 1);
     uint alloc_size=sizeof(TREE_ELEMENT)+key_size+tree->size_of_element;
     tree->allocated+=alloc_size;
 

sql/filesort.cc

@@ -50,10 +50,6 @@ static int write_keys(SORTPARAM *param,uchar * *sort_keys,
 		      uint count, IO_CACHE *buffer_file, IO_CACHE *tempfile);
 static void make_sortkey(SORTPARAM *param,uchar *to, uchar *ref_pos);
 static void register_used_fields(SORTPARAM *param);
-static int merge_index(SORTPARAM *param,uchar *sort_buffer,
-		       BUFFPEK *buffpek,
-		       uint maxbuffer,IO_CACHE *tempfile,
-		       IO_CACHE *outfile);
 static bool save_index(SORTPARAM *param,uchar **sort_keys, uint count, 
                        FILESORT_INFO *table_sort);
 static uint suffix_length(ulong string_length);
@@ -145,6 +141,7 @@ ha_rows filesort(THD *thd, TABLE *table, SORT_FIELD *sortorder, uint s_length,
   /* filesort cannot handle zero-length records. */
   DBUG_ASSERT(param.sort_length);
   param.ref_length= table->file->ref_length;
+  param.min_dupl_count= 0;
   param.addon_field= 0;
   param.addon_length= 0;
   if (!(table->file->ha_table_flags() & HA_FAST_KEY_READ) &&
@@ -1216,7 +1213,13 @@ int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
   rec_length= param->rec_length;
   res_length= param->res_length;
   sort_length= param->sort_length;
-  offset= rec_length-res_length;
+  element_count dupl_count;
+  uchar *src;
+  uint dupl_count_ofs= rec_length-sizeof(element_count);
+  uint min_dupl_count= param->min_dupl_count;
+  offset= rec_length-
+          (flag && min_dupl_count ? sizeof(dupl_count) : 0)-res_length;
+  uint wr_len= flag ? res_length : rec_length;
   maxcount= (ulong) (param->keys/((uint) (Tb-Fb) +1));
   to_start_filepos= my_b_tell(to_file);
   strpos= sort_buffer;
@@ -1262,16 +1265,20 @@ int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
     */
     buffpek= (BUFFPEK*) queue_top(&queue);
     memcpy(param->unique_buff, buffpek->key, rec_length);
-    if (my_b_write(to_file, (uchar*) buffpek->key, rec_length))
-    {
-      error=1; goto err;                        /* purecov: inspected */
-    }
+    if (min_dupl_count)
+      memcpy(&dupl_count, param->unique_buff+dupl_count_ofs, 
+             sizeof(dupl_count));
     buffpek->key+= rec_length;
-    buffpek->mem_count--;
-    if (!--max_rows)
+    if (! --buffpek->mem_count)
     {
-      error= 0;                                       /* purecov: inspected */
-      goto end;                                       /* purecov: inspected */
+      if (!(error= (int) read_to_buffer(from_file,buffpek,
+                                        rec_length)))
+      {
+        VOID(queue_remove(&queue,0));
+        reuse_freed_buff(&queue, buffpek, rec_length);
+      }
+      else if (error == -1)
+        goto err;                        /* purecov: inspected */ 
     }
     queue_replaced(&queue);                        // Top element has been used
   }
@@ -1287,27 +1294,42 @@ int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
     for (;;)
     {
       buffpek= (BUFFPEK*) queue_top(&queue);
+      src= buffpek->key;
       if (cmp)                                        // Remove duplicates
       {
         if (!(*cmp)(first_cmp_arg, &(param->unique_buff),
                     (uchar**) &buffpek->key))
-              goto skip_duplicate;
-            memcpy(param->unique_buff, (uchar*) buffpek->key, rec_length);
-      }
-      if (flag == 0)
-      {
-        if (my_b_write(to_file,(uchar*) buffpek->key, rec_length))
-        {
-          error=1; goto err;                        /* purecov: inspected */
+	{
+          if (min_dupl_count)
+	  {
+            element_count cnt;
+            memcpy(&cnt, (uchar *) buffpek->key+dupl_count_ofs, sizeof(cnt));
+            dupl_count+= cnt;
+          }
+          goto skip_duplicate;
         }
+        if (min_dupl_count)
+	{
+          memcpy(param->unique_buff+dupl_count_ofs, &dupl_count,
+                 sizeof(dupl_count));
+        }
+	src= param->unique_buff;
       }
-      else
+        
+      if (!flag || !min_dupl_count || dupl_count >= min_dupl_count)
       {
-        if (my_b_write(to_file, (uchar*) buffpek->key+offset, res_length))
+        if (my_b_write(to_file, src+(flag ? offset : 0), wr_len))
         {
           error=1; goto err;                        /* purecov: inspected */
         }
       }
+      if (cmp)
+      {   
+        memcpy(param->unique_buff, (uchar*) buffpek->key, rec_length);
+        if (min_dupl_count)
+          memcpy(&dupl_count, param->unique_buff+dupl_count_ofs, 
+                 sizeof(dupl_count));
+      }
       if (!--max_rows)
       {
         error= 0;                               /* purecov: inspected */
@@ -1343,9 +1365,33 @@ int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
   {
     if (!(*cmp)(first_cmp_arg, &(param->unique_buff), (uchar**) &buffpek->key))
     {
-      buffpek->key+= rec_length;         // Remove duplicate
+      if (min_dupl_count)
+      {
+        element_count cnt;
+        memcpy(&cnt, (uchar *) buffpek->key+dupl_count_ofs, sizeof(cnt));
+        dupl_count+= cnt;
+      }
+      buffpek->key+= rec_length;         
       --buffpek->mem_count;
     }
+
+    if (min_dupl_count)
+      memcpy(param->unique_buff+dupl_count_ofs, &dupl_count,
+             sizeof(dupl_count));
+          
+    if (!flag || !min_dupl_count || dupl_count >= min_dupl_count)
+    {
+      src= param->unique_buff;
+      if (my_b_write(to_file, src+(flag ? offset : 0), wr_len))
+      {
+        error=1; goto err;                        /* purecov: inspected */
+      }
+      if (!--max_rows)
+      {
+        error= 0;                               
+        goto end;                             
+      }
+    }   
   }
 
   do
@@ -1367,12 +1413,17 @@ int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
     else
     {
       register uchar *end;
-      strpos= buffpek->key+offset;
-      for (end= strpos+buffpek->mem_count*rec_length ;
-           strpos != end ;
-           strpos+= rec_length)
-      {     
-        if (my_b_write(to_file, strpos, res_length))
+      src= buffpek->key+offset;
+      for (end= src+buffpek->mem_count*rec_length ;
+           src != end ;
+           src+= rec_length)
+      {
+        if (flag && min_dupl_count &&
+            memcmp(&min_dupl_count, src+dupl_count_ofs, 
+                   sizeof(dupl_count_ofs))<0)
+	  continue;
+        
+        if (my_b_write(to_file, src, wr_len))
         {
           error=1; goto err;                        
         }
@@ -1393,7 +1444,7 @@ int merge_buffers(SORTPARAM *param, IO_CACHE *from_file,
 
 	/* Do a merge to output-file (save only positions) */
 
-static int merge_index(SORTPARAM *param, uchar *sort_buffer,
+int merge_index(SORTPARAM *param, uchar *sort_buffer,
 		       BUFFPEK *buffpek, uint maxbuffer,
 		       IO_CACHE *tempfile, IO_CACHE *outfile)
 {

sql/opt_range.cc

@@ -697,6 +697,9 @@ class SEL_TREE :public Sql_alloc
   key_map ror_scans_map;   /* bitmask of ROR scan-able elements in keys */
   uint    n_ror_scans;     /* number of set bits in ror_scans_map */
 
+  struct st_index_scan_info **index_scans;     /* list of index scans */
+  struct st_index_scan_info **index_scans_end; /* last index scan */
+
   struct st_ror_scan_info **ror_scans;     /* list of ROR key scans */
   struct st_ror_scan_info **ror_scans_end; /* last ROR scan */
   /* Note that #records for each key scan is stored in table->quick_rows */
@@ -776,9 +779,11 @@ class TABLE_READ_PLAN;
   class TRP_RANGE;
   class TRP_ROR_INTERSECT;
   class TRP_ROR_UNION;
+  class TRP_INDEX_INTERSECT;
   class TRP_INDEX_MERGE;
   class TRP_GROUP_MIN_MAX;
 
+struct st_index_scan_info;
 struct st_ror_scan_info;
 
 static SEL_TREE * get_mm_parts(RANGE_OPT_PARAM *param,COND *cond_func,Field *field,
@@ -804,6 +809,9 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
                                        bool update_tbl_stats,
                                        double read_time);
 static
+TRP_INDEX_INTERSECT *get_best_index_intersect(PARAM *param, SEL_TREE *tree,
+                                              double read_time);
+static
 TRP_ROR_INTERSECT *get_best_ror_intersect(const PARAM *param, SEL_TREE *tree,
                                           double read_time,
                                           bool *are_all_covering);
@@ -1747,7 +1755,7 @@ int QUICK_INDEX_MERGE_SELECT::init()
 int QUICK_INDEX_MERGE_SELECT::reset()
 {
   DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::reset");
-  DBUG_RETURN(read_keys_and_merge());
+  DBUG_RETURN (read_keys_and_merge());
 }
 
 bool
@@ -1783,6 +1791,64 @@ QUICK_INDEX_MERGE_SELECT::~QUICK_INDEX_MERGE_SELECT()
   DBUG_VOID_RETURN;
 }
 
+QUICK_INDEX_INTERSECT_SELECT::QUICK_INDEX_INTERSECT_SELECT(THD *thd_param,
+                                                           TABLE *table)
+  :pk_quick_select(NULL), thd(thd_param)
+{
+  DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::QUICK_INDEX_INTERSECT_SELECT");
+  index= MAX_KEY;
+  head= table;
+  bzero(&read_record, sizeof(read_record));
+  init_sql_alloc(&alloc, thd->variables.range_alloc_block_size, 0);
+  DBUG_VOID_RETURN;
+}
+
+int QUICK_INDEX_INTERSECT_SELECT::init()
+{
+  DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::init");
+  DBUG_RETURN(0);
+}
+
+int QUICK_INDEX_INTERSECT_SELECT::reset()
+{
+  DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::reset");
+  DBUG_RETURN (read_keys_and_merge());
+}
+
+bool
+QUICK_INDEX_INTERSECT_SELECT::push_quick_back(QUICK_RANGE_SELECT *quick_sel_range)
+{
+  /*
+    Save quick_select that does scan on clustered primary key as it will be
+    processed separately.
+  */
+  if (head->file->primary_key_is_clustered() &&
+      quick_sel_range->index == head->s->primary_key)
+    pk_quick_select= quick_sel_range;
+  else
+    return quick_selects.push_back(quick_sel_range);
+  return 0;
+}
+
+QUICK_INDEX_INTERSECT_SELECT::~QUICK_INDEX_INTERSECT_SELECT()
+{
+  List_iterator_fast<QUICK_RANGE_SELECT> quick_it(quick_selects);
+  QUICK_RANGE_SELECT* quick;
+  DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::~QUICK_INDEX_INTERSECT_SELECT");
+  delete unique;
+  quick_it.rewind();
+  while ((quick= quick_it++))
+    quick->file= NULL;
+  quick_selects.delete_elements();
+  delete pk_quick_select;
+  /* It's ok to call the next two even if they are already deinitialized */
+  end_read_record(&read_record);
+  free_io_cache(head);
+  free_root(&alloc,MYF(0));
+  DBUG_VOID_RETURN;
+}
+
+
 
 QUICK_ROR_INTERSECT_SELECT::QUICK_ROR_INTERSECT_SELECT(THD *thd_param,
                                                        TABLE *table,
@@ -2563,6 +2629,24 @@ class TRP_ROR_UNION : public TABLE_READ_PLAN
 };
 
 
+/*
+  Plan for QUICK_INDEX_INTERSECT_SELECT scan.
+  QUICK_INDEX_INTERSECT_SELECT always retrieves full rows, so retrieve_full_rows
+  is ignored by make_quick.
+*/
+
+class TRP_INDEX_INTERSECT : public TABLE_READ_PLAN
+{
+public:
+  TRP_INDEX_INTERSECT() {}                        /* Remove gcc warning */
+  virtual ~TRP_INDEX_INTERSECT() {}               /* Remove gcc warning */
+  QUICK_SELECT_I *make_quick(PARAM *param, bool retrieve_full_rows,
+                             MEM_ROOT *parent_alloc);
+  TRP_RANGE **range_scans; /* array of ptrs to plans of merged scans */
+  TRP_RANGE **range_scans_end; /* end of the array */
+};
+
+
 /*
   Plan for QUICK_INDEX_MERGE_SELECT scan.
   QUICK_ROR_INTERSECT_SELECT always retrieves full rows, so retrieve_full_rows
@@ -2630,6 +2714,30 @@ class TRP_GROUP_MIN_MAX : public TABLE_READ_PLAN
 };
 
 
+typedef struct st_index_scan_info
+{
+  uint      idx;      /* # of used key in param->keys */
+  uint      keynr;    /* # of used key in table */
+  uint      range_count;
+  ha_rows   records;  /* estimate of # records this scan will return */
+
+  /* Set of intervals over key fields that will be used for row retrieval. */
+  SEL_ARG   *sel_arg;
+
+  /* Fields used in the query and covered by this ROR scan. */
+  MY_BITMAP covered_fields;
+  uint      used_fields_covered; /* # of set bits in covered_fields */
+  int       key_rec_length; /* length of key record (including rowid) */
+
+  /*
+    Cost of reading all index records with values in sel_arg intervals set
+    (assuming there is no need to access full table records)
+  */
+  double    index_read_cost;
+  uint      first_uncovered_field; /* first unused bit in covered_fields */
+  uint      key_components; /* # of parts in the key */
+} INDEX_SCAN_INFO;
+
 /*
   Fill param->needed_fields with bitmap of fields used in the query.
   SYNOPSIS
@@ -2908,6 +3016,7 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
       */
       TRP_RANGE         *range_trp;
       TRP_ROR_INTERSECT *rori_trp;
+      TRP_INDEX_INTERSECT *intersect_trp;
       bool can_build_covering= FALSE;
       
       remove_nonrange_trees(&param, tree);
@@ -2947,6 +3056,18 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
             best_trp= rori_trp;
         }
       }
+#if 1
+#else
+      if (optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE))
+      {
+        if ((intersect_trp= get_best_index_intersect(&param, tree,
+                                                    best_read_time)))
+        {
+          best_trp= intersect_trp;
+          best_read_time= best_trp->read_cost;
+        }
+      }
+#endif
 
       if (optimizer_flag(thd, OPTIMIZER_SWITCH_INDEX_MERGE))
       {
@@ -4610,6 +4731,85 @@ TABLE_READ_PLAN *merge_same_index_scans(PARAM *param, SEL_IMERGE *imerge,
   DBUG_RETURN(trp); 
 }
 
+static
+TRP_INDEX_INTERSECT *get_best_index_intersect(PARAM *param, SEL_TREE *tree,
+                                              double read_time)
+{
+  uint i;
+  uint unique_calc_buff_size;
+  TRP_RANGE **cur_range;
+  TRP_RANGE **range_scans;
+  TRP_INDEX_INTERSECT *intersect_trp= NULL;
+  double intersect_cost= 0.0;
+  ha_rows scan_records= 0;
+  double selectivity= 1.0;
+  ha_rows table_records=  param->table->file->stats.records;
+  uint n_index_scans= tree->index_scans_end - tree->index_scans;
+  
+  DBUG_ENTER("get_best_index_intersect");
+
+  if (!n_index_scans)
+    DBUG_RETURN(NULL);
+
+  if (!(range_scans= (TRP_RANGE**)alloc_root(param->mem_root,
+                                            sizeof(TRP_RANGE *)*
+                                            n_index_scans)))
+    DBUG_RETURN(NULL);
+
+  for (i= 0, cur_range= range_scans; i < n_index_scans; i++)
+  {
+    struct st_index_scan_info *index_scan= tree->index_scans[i];
+    if ((*cur_range= new (param->mem_root) TRP_RANGE(index_scan->sel_arg,
+                                                     index_scan->idx)))
+    {  
+      TRP_RANGE *trp= *cur_range;    
+      trp->records= index_scan->records;
+      trp->is_ror= FALSE;
+      trp->read_cost= get_index_only_read_time(param, index_scan->records,
+                                               index_scan->keynr);
+      scan_records+= trp->records;
+      selectivity*= (double) trp->records/table_records;
+      intersect_cost+= trp->read_cost;
+      cur_range++;
+    }
+  }
+
+    /* Add Unique operations cost */
+  unique_calc_buff_size=
+    Unique::get_cost_calc_buff_size((ulong)scan_records,
+                                    param->table->file->ref_length,
+                                    param->thd->variables.sortbuff_size);
+  if (param->imerge_cost_buff_size < unique_calc_buff_size)
+  {
+    if (!(param->imerge_cost_buff= (uint*)alloc_root(param->mem_root,
+                                                     unique_calc_buff_size)))
+      DBUG_RETURN(NULL);
+    param->imerge_cost_buff_size= unique_calc_buff_size;
+  }
+
+  intersect_cost +=
+    Unique::get_use_cost(param->imerge_cost_buff, scan_records,
+                         param->table->file->ref_length,
+                         param->thd->variables.sortbuff_size);
+
+  intersect_cost += get_sweep_read_cost(param, 
+                                        (ha_rows) (table_records*selectivity));
+ 
+  if (intersect_cost < read_time)
+  {
+    if ((intersect_trp= new (param->mem_root)TRP_INDEX_INTERSECT))
+    {
+      intersect_trp->read_cost= intersect_cost;
+      intersect_trp->records= (ha_rows) table_records*selectivity;
+      set_if_bigger(intersect_trp->records, 1);
+      intersect_trp->range_scans= range_scans;
+      intersect_trp->range_scans_end= cur_range;
+      read_time= intersect_cost;
+    }
+  }
+  DBUG_RETURN(intersect_trp);
+}
+
 
 /*
   Calculate cost of 'index only' scan for given index and number of records.
@@ -4647,27 +4847,8 @@ static double get_index_only_read_time(const PARAM* param, ha_rows records,
 }
 
 
-typedef struct st_ror_scan_info
-{
-  uint      idx;      /* # of used key in param->keys */
-  uint      keynr;    /* # of used key in table */
-  ha_rows   records;  /* estimate of # records this scan will return */
-
-  /* Set of intervals over key fields that will be used for row retrieval. */
-  SEL_ARG   *sel_arg;
-
-  /* Fields used in the query and covered by this ROR scan. */
-  MY_BITMAP covered_fields;
-  uint      used_fields_covered; /* # of set bits in covered_fields */
-  int       key_rec_length; /* length of key record (including rowid) */
-
-  /*
-    Cost of reading all index records with values in sel_arg intervals set
-    (assuming there is no need to access full table records)
-  */
-  double    index_read_cost;
-  uint      first_uncovered_field; /* first unused bit in covered_fields */
-  uint      key_components; /* # of parts in the key */
+typedef struct st_ror_scan_info : INDEX_SCAN_INFO
+{ 
 } ROR_SCAN_INFO;
 
 
@@ -5526,6 +5707,14 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
                                       "tree scans"););
   tree->ror_scans_map.clear_all();
   tree->n_ror_scans= 0;
+  tree->index_scans= 0;
+  if (!tree->keys_map.is_clear_all())
+  {
+    tree->index_scans=
+      (INDEX_SCAN_INFO **) alloc_root(param->mem_root,
+                                      sizeof(INDEX_SCAN_INFO *) * param->keys);
+  }
+  tree->index_scans_end= tree->index_scans;                                                  
   for (idx= 0,key=tree->keys, end=key+param->keys;
        key != end ;
        key++,idx++)
@@ -5534,6 +5723,7 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
     double found_read_time;
     if (*key)
     {
+      INDEX_SCAN_INFO *index_scan;
       uint keynr= param->real_keynr[idx];
       if ((*key)->type == SEL_ARG::MAYBE_KEY ||
           (*key)->maybe_flag)
@@ -5543,6 +5733,17 @@ static TRP_RANGE *get_key_scans_params(PARAM *param, SEL_TREE *tree,
                             (bool) param->table->covering_keys.is_set(keynr);
 
       found_records= check_quick_select(param, idx, *key, update_tbl_stats);
+      if (found_records != HA_POS_ERROR && tree->index_scans &&
+          (index_scan= (INDEX_SCAN_INFO *)alloc_root(param->mem_root,
+						     sizeof(INDEX_SCAN_INFO))))
+      {
+        index_scan->idx= idx;
+        index_scan->keynr= keynr;
+        index_scan->range_count= param->range_count;
+        index_scan->records= found_records;
+        index_scan->sel_arg= *key;
+        *tree->index_scans_end++= index_scan;
+      }        
       if (param->is_ror_scan)
       {
         tree->n_ror_scans++;
@@ -5637,6 +5838,34 @@ QUICK_SELECT_I *TRP_INDEX_MERGE::make_quick(PARAM *param,
   return quick_imerge;
 }
 
+QUICK_SELECT_I *TRP_INDEX_INTERSECT::make_quick(PARAM *param,
+                                                bool retrieve_full_rows,
+                                                MEM_ROOT *parent_alloc)
+{
+  QUICK_INDEX_INTERSECT_SELECT *quick_intersect;
+  QUICK_RANGE_SELECT *quick;
+  /* index_merge always retrieves full rows, ignore retrieve_full_rows */
+  if (!(quick_intersect= new QUICK_INDEX_INTERSECT_SELECT(param->thd, param->table)))
+    return NULL;
+
+  quick_intersect->records= records;
+  quick_intersect->read_time= read_cost;
+  for (TRP_RANGE **range_scan= range_scans; range_scan != range_scans_end;
+       range_scan++)
+  {
+    if (!(quick= (QUICK_RANGE_SELECT*)
+          ((*range_scan)->make_quick(param, FALSE, &quick_intersect->alloc)))||
+        quick_intersect->push_quick_back(quick))
+    {
+      delete quick;
+      delete quick_intersect;
+      return NULL;
+    }
+  }
+  return quick_intersect;
+}
+
+
 QUICK_SELECT_I *TRP_ROR_INTERSECT::make_quick(PARAM *param,
                                               bool retrieve_full_rows,
                                               MEM_ROOT *parent_alloc)
@@ -9030,6 +9259,18 @@ bool QUICK_INDEX_MERGE_SELECT::is_keys_used(const MY_BITMAP *fields)
   return 0;
 }
 
+bool QUICK_INDEX_INTERSECT_SELECT::is_keys_used(const MY_BITMAP *fields)
+{
+  QUICK_RANGE_SELECT *quick;
+  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
+  while ((quick= it++))
+  {
+    if (is_key_used(head, quick->index, fields))
+      return 1;
+  }
+  return 0;
+}
+
 bool QUICK_ROR_INTERSECT_SELECT::is_keys_used(const MY_BITMAP *fields)
 {
   QUICK_RANGE_SELECT *quick;
@@ -9175,13 +9416,20 @@ QUICK_RANGE_SELECT *get_quick_select_for_ref(THD *thd, TABLE *table,
     other error
 */
 
-int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
+int read_keys_and_merge_scans(THD *thd,
+                              TABLE *head,
+                              List<QUICK_RANGE_SELECT> quick_selects,
+                              QUICK_RANGE_SELECT *pk_quick_select,
+                              READ_RECORD *read_record,
+                              bool intersection,
+                              Unique **unique_ptr)
 {
   List_iterator_fast<QUICK_RANGE_SELECT> cur_quick_it(quick_selects);
   QUICK_RANGE_SELECT* cur_quick;
   int result;
+  Unique *unique= *unique_ptr;
   handler *file= head->file;
-  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::read_keys_and_merge");
+  DBUG_ENTER("read_keys_and_merge");
 
   /* We're going to just read rowids. */
   if (!head->key_read)
@@ -9192,6 +9440,7 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
 
   cur_quick_it.rewind();
   cur_quick= cur_quick_it++;
+  bool first_quick= TRUE;
   DBUG_ASSERT(cur_quick != 0);
   
   /*
@@ -9209,9 +9458,11 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
 
     unique= new Unique(refpos_order_cmp, (void *)file,
                        file->ref_length,
-                       thd->variables.sortbuff_size);
+                       thd->variables.sortbuff_size,
+		       intersection ? quick_selects.elements : 0);                     
     if (!unique)
       goto err;
+    *unique_ptr= unique;
   }
   else
     unique->reset();
@@ -9223,6 +9474,12 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
   {
     while ((result= cur_quick->get_next()) == HA_ERR_END_OF_FILE)
     {
+      if (first_quick)
+      {
+        first_quick= FALSE;
+        if (intersection && unique->is_in_memory())
+          unique->close_for_expansion();
+      }
       cur_quick->range_end();
       cur_quick= cur_quick_it++;
       if (!cur_quick)
@@ -9262,12 +9519,11 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
     sequence.
   */
   result= unique->get(head);
-  doing_pk_scan= FALSE;
   /*
     index_merge currently doesn't support "using index" at all
   */
   head->disable_keyread();
-  init_read_record(&read_record, thd, head, (SQL_SELECT*) 0, 1 , 1, TRUE);
+  init_read_record(read_record, thd, head, (SQL_SELECT*) 0, 1 , 1, TRUE);
   DBUG_RETURN(result);
 
 err:
@@ -9276,6 +9532,17 @@ int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
 }
 
 
+int QUICK_INDEX_MERGE_SELECT::read_keys_and_merge()
+
+{
+  int result;
+  DBUG_ENTER("QUICK_INDEX_MERGE_SELECT::read_keys_and_merge");
+  result= read_keys_and_merge_scans(thd, head, quick_selects, pk_quick_select,
+                                    &read_record, FALSE, &unique);
+  doing_pk_scan= FALSE;
+  DBUG_RETURN(result);
+}
+
 /*
   Get next row for index_merge.
   NOTES
@@ -9312,6 +9579,44 @@ int QUICK_INDEX_MERGE_SELECT::get_next()
   DBUG_RETURN(result);
 }
 
+int QUICK_INDEX_INTERSECT_SELECT::read_keys_and_merge()
+
+{
+  int result;
+  DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::read_keys_and_merge");
+  result= read_keys_and_merge_scans(thd, head, quick_selects, pk_quick_select,
+                                    &read_record, TRUE, &unique);
+  doing_pk_scan= FALSE;
+  DBUG_RETURN(result);
+}
+
+int QUICK_INDEX_INTERSECT_SELECT::get_next()
+{
+  int result;
+  DBUG_ENTER("QUICK_INDEX_INTERSECT_SELECT::get_next");
+
+  if (doing_pk_scan)
+    DBUG_RETURN(pk_quick_select->get_next());
+
+  if ((result= read_record.read_record(&read_record)) == -1)
+  {
+    result= HA_ERR_END_OF_FILE;
+    end_read_record(&read_record);
+    free_io_cache(head);
+    /* All rows from Unique have been retrieved, do a clustered PK scan */
+    if (pk_quick_select)
+    {
+      doing_pk_scan= TRUE;
+      if ((result= pk_quick_select->init()) ||
+          (result= pk_quick_select->reset()))
+        DBUG_RETURN(result);
+      DBUG_RETURN(pk_quick_select->get_next());
+    }
+  }
+
+  DBUG_RETURN(result);
+}
+
 
 /*
   Retrieve next record.
@@ -10015,6 +10320,28 @@ void QUICK_INDEX_MERGE_SELECT::add_info_string(String *str)
   str->append(')');
 }
 
+void QUICK_INDEX_INTERSECT_SELECT::add_info_string(String *str)
+{
+  QUICK_RANGE_SELECT *quick;
+  bool first= TRUE;
+  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
+  str->append(STRING_WITH_LEN("sort_intersect("));
+  while ((quick= it++))
+  {
+    if (!first)
+      str->append(',');
+    else
+      first= FALSE;
+    quick->add_info_string(str);
+  }
+  if (pk_quick_select)
+  {
+    str->append(',');
+    pk_quick_select->add_info_string(str);
+  }
+  str->append(')');
+}
+
 void QUICK_ROR_INTERSECT_SELECT::add_info_string(String *str)
 {
   bool first= TRUE;
@@ -10039,6 +10366,7 @@ void QUICK_ROR_INTERSECT_SELECT::add_info_string(String *str)
   str->append(')');
 }
 
+
 void QUICK_ROR_UNION_SELECT::add_info_string(String *str)
 {
   bool first= TRUE;
@@ -10068,8 +10396,12 @@ void QUICK_RANGE_SELECT::add_keys_and_lengths(String *key_names,
   used_lengths->append(buf, length);
 }
 
-void QUICK_INDEX_MERGE_SELECT::add_keys_and_lengths(String *key_names,
-                                                    String *used_lengths)
+static
+void add_keys_and_lengths_of_index_scans(TABLE *head,
+                                         List<QUICK_RANGE_SELECT> quick_selects,
+                                         QUICK_RANGE_SELECT *pk_quick_select,
+                                         String *key_names,
+                                         String *used_lengths)
 {
   char buf[64];
   uint length;
@@ -10103,6 +10435,20 @@ void QUICK_INDEX_MERGE_SELECT::add_keys_and_lengths(String *key_names,
   }
 }
 
+void QUICK_INDEX_MERGE_SELECT::add_keys_and_lengths(String *key_names,
+                                                    String *used_lengths)
+{
+  add_keys_and_lengths_of_index_scans(head, quick_selects, pk_quick_select,
+                                      key_names, used_lengths);
+}
+
+void QUICK_INDEX_INTERSECT_SELECT::add_keys_and_lengths(String *key_names,
+                                                        String *used_lengths)
+{
+  add_keys_and_lengths_of_index_scans(head, quick_selects, pk_quick_select,
+                                      key_names, used_lengths);
+}
+
 void QUICK_ROR_INTERSECT_SELECT::add_keys_and_lengths(String *key_names,
                                                       String *used_lengths)
 {
@@ -12474,6 +12820,22 @@ void QUICK_INDEX_MERGE_SELECT::dbug_dump(int indent, bool verbose)
   fprintf(DBUG_FILE, "%*s}\n", indent, "");
 }
 
+void QUICK_INDEX_INTERSECT_SELECT::dbug_dump(int indent, bool verbose)
+{
+  List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);
+  QUICK_RANGE_SELECT *quick;
+  fprintf(DBUG_FILE, "%*squick index_intersect select\n", indent, "");
+  fprintf(DBUG_FILE, "%*smerged scans {\n", indent, "");
+  while ((quick= it++))
+    quick->dbug_dump(indent+2, verbose);
+  if (pk_quick_select)
+  {
+    fprintf(DBUG_FILE, "%*sclustered PK quick:\n", indent, "");
+    pk_quick_select->dbug_dump(indent+2, verbose);
+  }
+  fprintf(DBUG_FILE, "%*s}\n", indent, "");
+}
+
 void QUICK_ROR_INTERSECT_SELECT::dbug_dump(int indent, bool verbose)
 {
   List_iterator_fast<QUICK_RANGE_SELECT> it(quick_selects);

sql/opt_range.h

@@ -274,12 +274,13 @@ class QUICK_SELECT_I
 
   enum {
     QS_TYPE_RANGE = 0,
-    QS_TYPE_INDEX_MERGE = 1,
-    QS_TYPE_RANGE_DESC = 2,
-    QS_TYPE_FULLTEXT   = 3,
-    QS_TYPE_ROR_INTERSECT = 4,
-    QS_TYPE_ROR_UNION = 5,
-    QS_TYPE_GROUP_MIN_MAX = 6
+    QS_TYPE_INDEX_INTERSECT = 1,
+    QS_TYPE_INDEX_MERGE = 2,
+    QS_TYPE_RANGE_DESC = 3,
+    QS_TYPE_FULLTEXT   = 4,
+    QS_TYPE_ROR_INTERSECT = 5,
+    QS_TYPE_ROR_UNION = 6,
+    QS_TYPE_GROUP_MIN_MAX = 7
   };
 
   /* Get type of this quick select - one of the QS_TYPE_* values */
@@ -393,8 +394,17 @@ class QUICK_RANGE_SELECT : public QUICK_SELECT_I
   friend QUICK_RANGE_SELECT *get_quick_select(PARAM*,uint idx,
                                               SEL_ARG *key_tree,
                                               MEM_ROOT *alloc);
+  friend 
+  int read_keys_and_merge_scans(THD *thd, TABLE *head,
+                                List<QUICK_RANGE_SELECT> quick_selects,
+                                QUICK_RANGE_SELECT *pk_quick_select,
+                                READ_RECORD *read_record,
+                                bool intersection,
+                                Unique **unique_ptr);
+
   friend class QUICK_SELECT_DESC;
   friend class QUICK_INDEX_MERGE_SELECT;
+  friend class QUICK_INDEX_INTERSECT_SELECT;
   friend class QUICK_ROR_INTERSECT_SELECT;
   friend class QUICK_GROUP_MIN_MAX_SELECT;
 
@@ -545,6 +555,45 @@ class QUICK_INDEX_MERGE_SELECT : public QUICK_SELECT_I
   READ_RECORD read_record;
 };
 
+class QUICK_INDEX_INTERSECT_SELECT : public QUICK_SELECT_I
+{
+  Unique *unique;
+public:
+  QUICK_INDEX_INTERSECT_SELECT(THD *thd, TABLE *table);
+  ~QUICK_INDEX_INTERSECT_SELECT();
+
+  int  init();
+  int  reset(void);
+  int  get_next();
+  bool reverse_sorted() { return false; }
+  bool unique_key_range() { return false; }
+  int get_type() { return QS_TYPE_INDEX_INTERSECT; }
+  void add_keys_and_lengths(String *key_names, String *used_lengths);
+  void add_info_string(String *str);
+  bool is_keys_used(const MY_BITMAP *fields);
+#ifndef DBUG_OFF
+  void dbug_dump(int indent, bool verbose);
+#endif
+
+  bool push_quick_back(QUICK_RANGE_SELECT *quick_sel_range);
+
+  /* range quick selects this index_merge read consists of */
+  List<QUICK_RANGE_SELECT> quick_selects;
+
+  /* quick select that uses clustered primary key (NULL if none) */
+  QUICK_RANGE_SELECT* pk_quick_select;
+
+  /* true if this select is currently doing a clustered PK scan */
+  bool  doing_pk_scan;
+
+  MEM_ROOT alloc;
+  THD *thd;
+  int read_keys_and_merge();
+
+  /* used to get rows collected in Unique */
+  READ_RECORD read_record;
+};
+
 
 /*
   Rowid-Ordered Retrieval (ROR) index intersection quick select.

sql/sql_class.h

@@ -2949,6 +2949,7 @@ class user_var_entry
   DTCollation collation;
 };
 
+
 /*
    Unique -- class for unique (removing of duplicates).
    Puts all values to the TREE. If the tree becomes too big,
@@ -2967,11 +2968,14 @@ class Unique :public Sql_alloc
   uchar *record_pointers;
   bool flush();
   uint size;
+  uint full_size;
+  uint min_dupl_count;
 
 public:
   ulong elements;
   Unique(qsort_cmp2 comp_func, void *comp_func_fixed_arg,
-	 uint size_arg, ulonglong max_in_memory_size_arg);
+	 uint size_arg, ulonglong max_in_memory_size_arg,
+         uint min_dupl_count_arg= 0);
   ~Unique();
   ulong elements_in_tree() { return tree.elements_in_tree; }
   inline bool unique_add(void *ptr)
@@ -2983,6 +2987,9 @@ class Unique :public Sql_alloc
     DBUG_RETURN(!tree_insert(&tree, ptr, 0, tree.custom_arg));
   }
 
+  bool is_in_memory() { return (my_b_tell(&file) == 0); }
+  void close_for_expansion() { tree.flag= TREE_ONLY_DUPS; }
+
   bool get(TABLE *table);
   static double get_use_cost(uint *buffer, uint nkeys, uint key_size,
                              ulonglong max_in_memory_size);
@@ -3002,6 +3009,11 @@ class Unique :public Sql_alloc
 
   friend int unique_write_to_file(uchar* key, element_count count, Unique *unique);
   friend int unique_write_to_ptrs(uchar* key, element_count count, Unique *unique);
+
+  friend int unique_write_to_file_with_count(uchar* key, element_count count,
+                                             Unique *unique);
+  friend int unique_intersect_write_to_ptrs(uchar* key, element_count count, 
+				            Unique *unique);
 };
 
 

sql/sql_select.cc

@@ -13643,7 +13643,8 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
       by clustered PK values.
     */
   
-    if (quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE || 
+    if (quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE ||
+        quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_INTERSECT || 
         quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION || 
         quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT)
       DBUG_RETURN(0);
@@ -14049,6 +14050,7 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
         QUICK_SELECT_DESC *tmp;
         int quick_type= select->quick->get_type();
         if (quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE ||
+            quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_INTERSECT ||
             quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT ||
             quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION ||
             quick_type == QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX)
@@ -16817,6 +16819,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
       {
         quick_type= tab->select->quick->get_type();
         if ((quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE) ||
+            (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT) ||
             (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT) ||
             (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION))
           tab->type = JT_INDEX_MERGE;
@@ -17022,6 +17025,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
       {
         if (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION || 
             quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT ||
+            quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_INTERSECT ||
             quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_MERGE)
         {
           extra.append(STRING_WITH_LEN("; Using "));

sql/sql_sort.h

@@ -57,6 +57,7 @@ typedef struct st_sort_param {
   uint addon_length;        /* Length of added packed fields */
   uint res_length;          /* Length of records in final sorted file/buffer */
   uint keys;				/* Max keys / buffer */
+  element_count min_dupl_count;
   ha_rows max_rows,examined_rows;
   TABLE *sort_form;			/* For quicker make_sortkey */
   SORT_FIELD *local_sortorder;
@@ -80,4 +81,9 @@ int merge_buffers(SORTPARAM *param,IO_CACHE *from_file,
 		  IO_CACHE *to_file, uchar *sort_buffer,
 		  BUFFPEK *lastbuff,BUFFPEK *Fb,
 		  BUFFPEK *Tb,int flag);
+int merge_index(SORTPARAM *param, uchar *sort_buffer,
+		BUFFPEK *buffpek, uint maxbuffer,
+		IO_CACHE *tempfile, IO_CACHE *outfile);
+
 void reuse_freed_buff(QUEUE *queue, BUFFPEK *reuse, uint key_length);
+

sql/uniques.cc

@@ -33,7 +33,6 @@
 #include "mysql_priv.h"
 #include "sql_sort.h"
 
-
 int unique_write_to_file(uchar* key, element_count count, Unique *unique)
 {
   /*
@@ -45,6 +44,12 @@ int unique_write_to_file(uchar* key, element_count count, Unique *unique)
   return my_b_write(&unique->file, key, unique->size) ? 1 : 0;
 }
 
+int unique_write_to_file_with_count(uchar* key, element_count count, Unique *unique)
+{
+  return my_b_write(&unique->file, key, unique->size) ||
+         my_b_write(&unique->file, &count, sizeof(element_count)) ? 1 : 0;
+}
+
 int unique_write_to_ptrs(uchar* key, element_count count, Unique *unique)
 {
   memcpy(unique->record_pointers, key, unique->size);
@@ -52,10 +57,26 @@ int unique_write_to_ptrs(uchar* key, element_count count, Unique *unique)
   return 0;
 }
 
+int unique_intersect_write_to_ptrs(uchar* key, element_count count, Unique *unique)
+{
+  if (count >= unique->min_dupl_count)
+  {
+    memcpy(unique->record_pointers, key, unique->size);
+    unique->record_pointers+=unique->size;
+  }
+  return 0;
+}
+
+
 Unique::Unique(qsort_cmp2 comp_func, void * comp_func_fixed_arg,
-	       uint size_arg, ulonglong max_in_memory_size_arg)
+	       uint size_arg, ulonglong max_in_memory_size_arg,
+               uint min_dupl_count_arg)
   :max_in_memory_size(max_in_memory_size_arg), size(size_arg), elements(0)
 {
+  min_dupl_count= min_dupl_count_arg;
+  full_size= size;
+  if (min_dupl_count_arg)
+    full_size+= sizeof(element_count);
   my_b_clear(&file);
   init_tree(&tree, (ulong) (max_in_memory_size / 16), 0, size, comp_func, 0,
             NULL, comp_func_fixed_arg);
@@ -276,7 +297,11 @@ double Unique::get_use_cost(uint *buffer, uint nkeys, uint key_size,
   result= 2*log2_n_fact(last_tree_elems + 1.0);
   if (n_full_trees)
     result+= n_full_trees * log2_n_fact(max_elements_in_tree + 1.0);
+#if 1
   result /= TIME_FOR_COMPARE_ROWID;
+#else
+  result /= TIME_FOR_COMPARE_ROWID * 10;
+#endif
 
   DBUG_PRINT("info",("unique trees sizes: %u=%u*%lu + %lu", nkeys,
                      n_full_trees, n_full_trees?max_elements_in_tree:0,
@@ -327,7 +352,10 @@ bool Unique::flush()
   file_ptr.count=tree.elements_in_tree;
   file_ptr.file_pos=my_b_tell(&file);
 
-  if (tree_walk(&tree, (tree_walk_action) unique_write_to_file,
+  tree_walk_action action= min_dupl_count ?
+		           (tree_walk_action) unique_write_to_file_with_count :
+		           (tree_walk_action) unique_write_to_file;
+  if (tree_walk(&tree, action,
 		(void*) this, left_root_right) ||
       insert_dynamic(&file_ptrs, (uchar*) &file_ptr))
     return 1;
@@ -357,6 +385,7 @@ Unique::reset()
     reinit_io_cache(&file, WRITE_CACHE, 0L, 0, 1);
   }
   elements= 0;
+  tree.flag= 0;
 }
 
 /*
@@ -576,14 +605,16 @@ bool Unique::get(TABLE *table)
 {
   SORTPARAM sort_param;
   table->sort.found_records=elements+tree.elements_in_tree;
-
   if (my_b_tell(&file) == 0)
   {
     /* Whole tree is in memory;  Don't use disk if you don't need to */
     if ((record_pointers=table->sort.record_pointers= (uchar*)
 	 my_malloc(size * tree.elements_in_tree, MYF(0))))
     {
-      (void) tree_walk(&tree, (tree_walk_action) unique_write_to_ptrs,
+      tree_walk_action action= min_dupl_count ?
+		         (tree_walk_action) unique_intersect_write_to_ptrs :
+		         (tree_walk_action) unique_write_to_ptrs;
+      (void) tree_walk(&tree, action,
 		       this, left_root_right);
       return 0;
     }
@@ -614,7 +645,10 @@ bool Unique::get(TABLE *table)
   sort_param.max_rows= elements;
   sort_param.sort_form=table;
   sort_param.rec_length= sort_param.sort_length= sort_param.ref_length=
-    size;
+  sort_param.rec_length= sort_param.sort_length= sort_param.ref_length=
+   full_size;
+  sort_param.min_dupl_count= min_dupl_count;
+  sort_param.res_length= 0;
   sort_param.keys= (uint) (max_in_memory_size / sort_param.sort_length);
   sort_param.not_killable=1;
 
@@ -635,8 +669,9 @@ bool Unique::get(TABLE *table)
   if (flush_io_cache(&file) ||
       reinit_io_cache(&file,READ_CACHE,0L,0,0))
     goto err;
-  if (merge_buffers(&sort_param, &file, outfile, sort_buffer, file_ptr,
-		    file_ptr, file_ptr+maxbuffer,0))
+  sort_param.res_length= sort_param.rec_length-
+                         (min_dupl_count ? sizeof(min_dupl_count) : 0);
+  if (merge_index(&sort_param, sort_buffer, file_ptr, maxbuffer, &file, outfile))
     goto err;
   error=0;
 err: