Merge 5.3->5.5

mysql-test/r/sp.result

@@ -6530,16 +6530,16 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	c1	c1	5	const	1	Using index
 EXPLAIN SELECT * FROM t1 WHERE c1=f1();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	c1	c1	5	const	0	Using where; Using index
+1	SIMPLE	t1	ref	c1	c1	5	const	1	Using where; Using index
 EXPLAIN SELECT * FROM v1 WHERE c1=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ref	c1	c1	5	const	1	Using index
 EXPLAIN SELECT * FROM v1 WHERE c1=f1();
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	c1	c1	5	const	0	Using where; Using index
+1	SIMPLE	t1	ref	c1	c1	5	const	1	Using where; Using index
 EXPLAIN SELECT * FROM t1 WHERE c1=f2(10);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ref	c1	c1	5	const	0	Using where; Using index
+1	SIMPLE	t1	ref	c1	c1	5	const	1	Using where; Using index
 EXPLAIN SELECT * FROM t1 WHERE c1=f2(c1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	index	NULL	c1	5	NULL	5	Using where; Using index
@@ -7852,6 +7852,38 @@ c1	c2	count(c3)
 2012-03-01 01:00:00	3	1
 2012-03-01 02:00:00	3	1
 DROP PROCEDURE p1;
+
+MDEV-3900 Optimizer difference between MySQL and MariaDB with stored functions in WHERE clause of UPDATE or DELETE statements
+
+CREATE FUNCTION tdn() RETURNS int(7) DETERMINISTIC RETURN to_days(now());
+CREATE TABLE t1 (pk INT NOT NULL AUTO_INCREMENT PRIMARY KEY, daynum INT, a CHAR(1), INDEX(daynum), INDEX(a)) ENGINE=MyISAM;
+INSERT INTO t1 (daynum) VALUES (1),(2),(3),(4),(5),(TO_DAYS(NOW())),(7),(8);
+INSERT INTO t1 (daynum) SELECT a1.daynum FROM t1 a1, t1 a2, t1 a3, t1 a4, t1 a5;
+FLUSH TABLES;
+FLUSH STATUS;
+SHOW STATUS LIKE '%Handler_read%';
+Variable_name	Value
+Handler_read_first	0
+Handler_read_key	0
+Handler_read_last	0
+Handler_read_next	0
+Handler_read_prev	0
+Handler_read_rnd	0
+Handler_read_rnd_deleted	0
+Handler_read_rnd_next	0
+UPDATE t1 SET a = '+' WHERE daynum=tdn();
+SHOW STATUS LIKE '%Handler_read%';
+Variable_name	Value
+Handler_read_first	0
+Handler_read_key	2
+Handler_read_last	0
+Handler_read_next	4097
+Handler_read_prev	0
+Handler_read_rnd	0
+Handler_read_rnd_deleted	0
+Handler_read_rnd_next	0
+drop function tdn;
+drop table t1;
 #
 # lp:1002157 : testing stored function
 # bug#62125        result for null incorrectly yields 1292 warning.

mysql-test/r/subselect4.result

@@ -2274,6 +2274,27 @@ SELECT a3 FROM t3 WHERE b2 = b1 AND b2 <= b1 ORDER BY b3
 a1	b1
 drop table t1, t2, t3;
 #
+# MDEV-4056:Server crashes in Item_func_trig_cond::val_int
+# with FROM and NOT IN subqueries, LEFT JOIN, derived_merge+in_to_exists
+#
+set @optimizer_switch_MDEV4056 = @@optimizer_switch;
+SET optimizer_switch = 'derived_merge=on,in_to_exists=on';
+CREATE TABLE t1 (a VARCHAR(1)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ('x'),('d');
+CREATE TABLE t2 (pk INT PRIMARY KEY, b INT, c VARCHAR(1))  ENGINE=MyISAM;
+INSERT INTO t2 VALUES (1,2,'v'),(2,150,'v');
+SELECT * FROM t1 LEFT JOIN (  
+SELECT * FROM t2 WHERE ( pk, pk ) NOT IN ( 
+SELECT MIN(b), SUM(pk) FROM t1
+) 
+) AS alias1 ON (a = c) 
+WHERE b IS NULL OR a < 'u';
+a	pk	b	c
+x	NULL	NULL	NULL
+d	NULL	NULL	NULL
+drop table t1,t2;
+set @@optimizer_switch = @optimizer_switch_MDEV4056;
+#
 # MDEV-3899  Valgrind warnings (blocks are definitely lost) in filesort on IN subquery with SUM and DISTINCT
 #
 CREATE TABLE t1 (a INT) ENGINE=MyISAM;

mysql-test/r/subselect_innodb.result

@@ -391,4 +391,22 @@ select 1 from t1 where 1 like (select 1 from t1 where 1 <=> (select 1 from t1 gr
 1
 1
 drop table t1;
+#
+# MDEV-3988 crash in create_tmp_table
+#
+drop table if exists `t1`,`t2`;
+Warnings:
+Note	1051	Unknown table 't1'
+Note	1051	Unknown table 't2'
+create table `t1`(`a` char(1) character set utf8)engine=innodb;
+create table `t2`(`b` char(1) character set utf8)engine=memory;
+select distinct (select 1 from `t2` where `a`) `d2` from `t1`;
+d2
+select distinct (select 1 from `t2` where `a`) `d2`, a from `t1`;
+d2	a
+select distinct a, (select 1 from `t2` where `a`) `d2` from `t1`;
+a	d2
+select distinct (1 + (select 1 from `t2` where `a`)) `d2` from `t1`;
+d2
+drop table t1,t2;
 set optimizer_switch=@subselect_innodb_tmp;

mysql-test/r/sum_distinct-big.result

@@ -103,5 +103,20 @@ sm
 10323810
 10325070
 10326330
+# 
+# Bug mdev-4063: SUM(DISTINCT...) with small'max_heap_table_size 
+# (bug #56927)
+# 
+SET max_heap_table_size=default;
+INSERT INTO t1 SELECT id+16384 FROM t1;
+DELETE FROM t2;
+INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
+SELECT SUM(DISTINCT id) sm FROM t2;
+sm
+536887296
+SET max_heap_table_size=16384;
+SELECT SUM(DISTINCT id) sm FROM t2;
+sm
+536887296
 DROP TABLE t1;
 DROP TABLE t2;

mysql-test/r/type_year.result

@@ -389,6 +389,7 @@ select a from t1 where a=(select 2000 from dual where 1);
 a
 select a from t1 where a=y2k();
 a
+00
 select a from t1 where a=b;
 a
 drop table t1;

mysql-test/suite/vcol/r/vcol_misc.result

@@ -182,6 +182,17 @@ a	b	c
 2	3	y
 0	1	y,n
 drop table t1,t2;
+CREATE TABLE t1 (
+ts TIMESTAMP,
+tsv TIMESTAMP AS (ADDDATE(ts, INTERVAL 1 DAY)) VIRTUAL
+) ENGINE=MyISAM;
+INSERT INTO t1 (tsv) VALUES (DEFAULT);
+INSERT DELAYED INTO t1 (tsv) VALUES (DEFAULT);
+FLUSH TABLES;
+SELECT COUNT(*) FROM t1;
+COUNT(*)
+2
+DROP TABLE t1;
 create table t1 (a int, b int);
 insert into t1 values (3, 30), (4, 20), (1, 20);
 create table t2 (c int, d int, v int as (d+1), index idx(c));

mysql-test/suite/vcol/t/vcol_misc.test

@@ -178,6 +178,25 @@ select * from t2;
 
 drop table t1,t2;
 
+#
+# Bug mdev-3938: INSERT DELAYED for a table with virtual columns
+#
+
+CREATE TABLE t1 (
+ ts TIMESTAMP,
+ tsv TIMESTAMP AS (ADDDATE(ts, INTERVAL 1 DAY)) VIRTUAL
+) ENGINE=MyISAM;
+
+INSERT INTO t1 (tsv) VALUES (DEFAULT);
+
+INSERT DELAYED INTO t1 (tsv) VALUES (DEFAULT);
+
+FLUSH TABLES;
+
+SELECT COUNT(*) FROM t1;
+
+DROP TABLE t1;
+
 #
 #  SELECT that uses a virtual column and executed with BKA
 #

mysql-test/t/sp.test

@@ -9151,6 +9151,26 @@ CALL p1(1);
 
 DROP PROCEDURE p1; 
 
+--echo
+--echo MDEV-3900 Optimizer difference between MySQL and MariaDB with stored functions in WHERE clause of UPDATE or DELETE statements
+--echo
+
+CREATE FUNCTION tdn() RETURNS int(7) DETERMINISTIC RETURN to_days(now());
+
+CREATE TABLE t1 (pk INT NOT NULL AUTO_INCREMENT PRIMARY KEY, daynum INT, a CHAR(1), INDEX(daynum), INDEX(a)) ENGINE=MyISAM;
+INSERT INTO t1 (daynum) VALUES (1),(2),(3),(4),(5),(TO_DAYS(NOW())),(7),(8);
+INSERT INTO t1 (daynum) SELECT a1.daynum FROM t1 a1, t1 a2, t1 a3, t1 a4, t1 a5;
+
+FLUSH TABLES;
+FLUSH STATUS;
+
+SHOW STATUS LIKE '%Handler_read%';
+UPDATE t1 SET a = '+' WHERE daynum=tdn();
+SHOW STATUS LIKE '%Handler_read%';
+
+drop function tdn;
+drop table t1;
+
 --echo #
 --echo # lp:1002157 : testing stored function
 --echo # bug#62125        result for null incorrectly yields 1292 warning.

mysql-test/t/subselect4.test

@@ -1804,6 +1804,30 @@ SELECT * FROM t1 WHERE a1 IN (
 );
 drop table t1, t2, t3;
 
+--echo #
+--echo # MDEV-4056:Server crashes in Item_func_trig_cond::val_int
+--echo # with FROM and NOT IN subqueries, LEFT JOIN, derived_merge+in_to_exists
+--echo #
+
+set @optimizer_switch_MDEV4056 = @@optimizer_switch;
+SET optimizer_switch = 'derived_merge=on,in_to_exists=on';
+
+CREATE TABLE t1 (a VARCHAR(1)) ENGINE=MyISAM;
+INSERT INTO t1 VALUES ('x'),('d');
+
+CREATE TABLE t2 (pk INT PRIMARY KEY, b INT, c VARCHAR(1))  ENGINE=MyISAM;
+INSERT INTO t2 VALUES (1,2,'v'),(2,150,'v');
+
+SELECT * FROM t1 LEFT JOIN (  
+  SELECT * FROM t2 WHERE ( pk, pk ) NOT IN ( 
+    SELECT MIN(b), SUM(pk) FROM t1
+  ) 
+) AS alias1 ON (a = c) 
+WHERE b IS NULL OR a < 'u';
+
+drop table t1,t2;
+set @@optimizer_switch = @optimizer_switch_MDEV4056;
+
 --echo #
 --echo # MDEV-3899  Valgrind warnings (blocks are definitely lost) in filesort on IN subquery with SUM and DISTINCT
 --echo #

mysql-test/t/subselect_innodb.test

@@ -377,4 +377,18 @@ select 1 from t1 where 1 like (select 1 from t1 where 1 <=> (select 1 from t1 gr
 drop table t1;
 
 
+--echo #
+--echo # MDEV-3988 crash in create_tmp_table
+--echo #
+
+drop table if exists `t1`,`t2`;
+create table `t1`(`a` char(1) character set utf8)engine=innodb;
+create table `t2`(`b` char(1) character set utf8)engine=memory;
+select distinct (select 1 from `t2` where `a`) `d2` from `t1`;
+select distinct (select 1 from `t2` where `a`) `d2`, a from `t1`;
+select distinct a, (select 1 from `t2` where `a`) `d2` from `t1`;
+select distinct (1 + (select 1 from `t2` where `a`)) `d2` from `t1`;
+
+drop table t1,t2;
+
 set optimizer_switch=@subselect_innodb_tmp;

mysql-test/t/sum_distinct-big.test

@@ -63,5 +63,22 @@ SELECT SUM(DISTINCT id) sm FROM t1;
 SELECT SUM(DISTINCT id) sm FROM t2;
 SELECT SUM(DISTINCT id) sm FROM t1 GROUP BY id % 13;
 
+--echo # 
+--echo # Bug mdev-4063: SUM(DISTINCT...) with small'max_heap_table_size 
+--echo # (bug #56927)
+--echo # 
+
+SET max_heap_table_size=default;
+
+INSERT INTO t1 SELECT id+16384 FROM t1;
+DELETE FROM t2;
+INSERT INTO t2 SELECT id FROM t1 ORDER BY id*rand();
+
+SELECT SUM(DISTINCT id) sm FROM t2;
+
+SET max_heap_table_size=16384;
+
+SELECT SUM(DISTINCT id) sm FROM t2;
+
 DROP TABLE t1;
 DROP TABLE t2;

sql/item_func.cc

@@ -6524,6 +6524,19 @@ Item_func_sp::init_result_field(THD *thd)
 }
 
 
+/**
+  @note
+  Deterministic stored procedures are considered inexpensive.
+  Consequently such procedures may be evaluated during optimization,
+  if they are constant (checked by the optimizer).
+*/
+
+bool Item_func_sp::is_expensive()
+{
+  return !(m_sp->m_chistics->detistic);
+}
+
+
 /**
   @brief Initialize local members with values from the Field interface.
 

sql/item_func.h

@@ -1907,7 +1907,8 @@ private:
   bool init_result_field(THD *thd);
 
 protected:
-  bool is_expensive_processor(uchar *arg) { return TRUE; }
+  bool is_expensive_processor(uchar *arg)
+  { return is_expensive(); }
   
 public:
 
@@ -1986,7 +1987,7 @@ public:
 
   bool fix_fields(THD *thd, Item **ref);
   void fix_length_and_dec(void);
-  bool is_expensive() { return 1; }
+  bool is_expensive();
 
   inline Field *get_sp_result_field()
   {

sql/item_row.cc

@@ -145,11 +145,13 @@ void Item_row::update_used_tables()
 {
   used_tables_cache= 0;
   const_item_cache= 1;
+  maybe_null= 0;
   for (uint i= 0; i < arg_count; i++)
   {
     items[i]->update_used_tables();
     used_tables_cache|= items[i]->used_tables();
     const_item_cache&= items[i]->const_item();
+    maybe_null|= items[i]->maybe_null;
   }
 }
 

sql/item_sum.cc

@@ -1086,7 +1086,7 @@ void Aggregator_distinct::endup()
   {
     /* go over the tree of distinct keys and calculate the aggregate value */
     use_distinct_values= TRUE;
-    tree->walk(item_sum_distinct_walk, (void*) this);
+    tree->walk(table, item_sum_distinct_walk, (void*) this);
     use_distinct_values= FALSE;
   }
   /* prevent consecutive recalculations */

sql/sql_base.cc

@@ -8939,7 +8939,8 @@ fill_record(THD * thd, List<Item> &fields, List<Item> &values,
                           ER(ER_WARNING_NON_DEFAULT_VALUE_FOR_VIRTUAL_COLUMN),
                           rfield->field_name, table->s->table_name.str);
     }
-    if ((value->save_in_field(rfield, 0) < 0) && !ignore_errors)
+    if ((!rfield->vcol_info || rfield->stored_in_db) && 
+        (value->save_in_field(rfield, 0)) < 0 && !ignore_errors)
     {
       my_message(ER_UNKNOWN_ERROR, ER(ER_UNKNOWN_ERROR), MYF(0));
       goto err;

sql/sql_class.h

@@ -3856,6 +3856,8 @@ class Unique :public Sql_alloc
   uint full_size;
   uint min_dupl_count;   /* always 0 for unions, > 0 for intersections */
 
+  bool merge(TABLE *table, uchar *buff, bool without_last_merge);
+
 public:
   ulong elements;
   Unique(qsort_cmp2 comp_func, void *comp_func_fixed_arg,
@@ -3896,7 +3898,7 @@ public:
   }
 
   void reset();
-  bool walk(tree_walk_action action, void *walk_action_arg);
+  bool walk(TABLE *table, tree_walk_action action, void *walk_action_arg);
 
   uint get_size() const { return size; }
   ulonglong get_max_in_memory_size() const { return max_in_memory_size; }

sql/sql_insert.cc

@@ -2320,6 +2320,7 @@ TABLE *Delayed_insert::get_local_table(THD* client_thd)
 {
   my_ptrdiff_t adjust_ptrs;
   Field **field,**org_field, *found_next_number_field;
+  Field **vfield;
   TABLE *copy;
   TABLE_SHARE *share;
   uchar *bitmap;
@@ -2379,6 +2380,13 @@ TABLE *Delayed_insert::get_local_table(THD* client_thd)
   if (!copy_tmp)
     goto error;
 
+  if (share->vfields)
+  {
+    vfield= (Field **) client_thd->alloc((share->vfields+1)*sizeof(Field*));
+    if (!vfield)
+      goto error;
+  }
+
   /* Copy the TABLE object. */
   copy= new (copy_tmp) TABLE;
   *copy= *table;
@@ -2408,6 +2416,27 @@ TABLE *Delayed_insert::get_local_table(THD* client_thd)
   }
   *field=0;
 
+  if (share->vfields)
+  {
+    copy->vfield= vfield;
+    for (field= copy->field; *field; field++)
+    {
+      if ((*field)->vcol_info)
+      {
+        bool error_reported= FALSE;
+        if (unpack_vcol_info_from_frm(client_thd,
+                                      client_thd->mem_root,
+                                      copy,
+                                      *field,
+                                      &(*field)->vcol_info->expr_str,
+                                      &error_reported))
+          goto error;
+        *vfield++= *field;
+      }
+    }
+    *vfield= 0; 
+  }
+
   /* Adjust timestamp */
   if (table->timestamp_field)
   {

sql/sql_select.cc

@@ -14176,10 +14176,20 @@ create_tmp_table(THD *thd, TMP_TABLE_PARAM *param, List<Item> &fields,
 
   if (group)
   {
+    ORDER **prev= &group;
     if (!param->quick_group)
       group=0;					// Can't use group key
     else for (ORDER *tmp=group ; tmp ; tmp=tmp->next)
     {
+      /* Exclude found constant from the list */
+      if ((*tmp->item)->const_item())
+      {
+        *prev= tmp->next;
+        param->group_parts--;
+        continue;
+      }
+      else
+        prev= &(tmp->next);
       /*
         marker == 4 means two things:
         - store NULLs in the key, and

sql/table.cc

@@ -2138,8 +2138,10 @@ end:
   @brief
     Unpack the definition of a virtual column from its linear representation
 
-  @parm
+  @param
     thd                  The thread object
+  @param
+    mem_root             The mem_root object where to allocated memory 
   @param
     table                The table containing the virtual column
   @param
@@ -2169,6 +2171,7 @@ end:
     TRUE            Otherwise
 */
 bool unpack_vcol_info_from_frm(THD *thd,
+                               MEM_ROOT *mem_root,
                                TABLE *table,
                                Field *field,
                                LEX_STRING *vcol_expr,
@@ -2196,7 +2199,7 @@ bool unpack_vcol_info_from_frm(THD *thd,
     "PARSE_VCOL_EXPR (<expr_string_from_frm>)".
   */
   
-  if (!(vcol_expr_str= (char*) alloc_root(&table->mem_root,
+  if (!(vcol_expr_str= (char*) alloc_root(mem_root,
                                           vcol_expr->length + 
                                             parse_vcol_keyword.length + 3)))
   {
@@ -2230,10 +2233,10 @@ bool unpack_vcol_info_from_frm(THD *thd,
       We need to use CONVENTIONAL_EXECUTION here to ensure that
       any new items created by fix_fields() are not reverted.
     */
-    Query_arena expr_arena(&table->mem_root,
+    Query_arena expr_arena(mem_root,
                            Query_arena::STMT_CONVENTIONAL_EXECUTION);
-    if (!(vcol_arena= (Query_arena *) alloc_root(&table->mem_root,
-                                                 sizeof(Query_arena))))
+    if (!(vcol_arena= (Query_arena *) alloc_root(mem_root,
+                                               sizeof(Query_arena))))
       goto err;
     *vcol_arena= expr_arena;
     table->expr_arena= vcol_arena;
@@ -2491,6 +2494,7 @@ int open_table_from_share(THD *thd, TABLE_SHARE *share, const char *alias,
       if ((*field_ptr)->vcol_info)
       {
         if (unpack_vcol_info_from_frm(thd,
+                                      &outparam->mem_root,
                                       outparam,
                                       *field_ptr,
                                       &(*field_ptr)->vcol_info->expr_str,

sql/table.h

@@ -2373,6 +2373,9 @@ void init_mdl_requests(TABLE_LIST *table_list);
 int open_table_from_share(THD *thd, TABLE_SHARE *share, const char *alias,
                           uint db_stat, uint prgflag, uint ha_open_flags,
                           TABLE *outparam, bool is_create_table);
+bool unpack_vcol_info_from_frm(THD *thd, MEM_ROOT *mem_root,
+                               TABLE *table, Field *field,
+                               LEX_STRING *vcol_expr, bool *error_reported);
 TABLE_SHARE *alloc_table_share(TABLE_LIST *table_list, char *key,
                                uint key_length);
 void init_tmp_table_share(THD *thd, TABLE_SHARE *share, const char *key,

sql/uniques.cc

@@ -584,6 +584,7 @@ end:
   SYNOPSIS
     Unique:walk()
   All params are 'IN':
+    table   parameter for the call of the merge method
     action  function-visitor, typed in include/my_tree.h
             function is called for each unique element
     arg     argument for visitor, which is passed to it on each call
@@ -592,72 +593,68 @@ end:
     <> 0 error
  */
 
-bool Unique::walk(tree_walk_action action, void *walk_action_arg)
+bool Unique::walk(TABLE *table, tree_walk_action action, void *walk_action_arg)
 {
-  int res;
+  int res= 0;
   uchar *merge_buffer;
 
   if (elements == 0)                       /* the whole tree is in memory */
     return tree_walk(&tree, action, walk_action_arg, left_root_right);
 
+  table->sort.found_records=elements+tree.elements_in_tree;
   /* flush current tree to the file to have some memory for merge buffer */
   if (flush())
     return 1;
   if (flush_io_cache(&file) || reinit_io_cache(&file, READ_CACHE, 0L, 0, 0))
     return 1;
-  if (!(merge_buffer= (uchar *) my_malloc((ulong) max_in_memory_size, MYF(0))))
+  ulong buff_sz= (max_in_memory_size / full_size + 1) * full_size;
+  if (!(merge_buffer= (uchar *) my_malloc((ulong) buff_sz, MYF(0))))
     return 1;
-  res= merge_walk(merge_buffer, (ulong) max_in_memory_size, size,
-                  (BUFFPEK *) file_ptrs.buffer,
-                  (BUFFPEK *) file_ptrs.buffer + file_ptrs.elements,
-                  action, walk_action_arg,
-                  tree.compare, tree.custom_arg, &file);
+  if (buff_sz < (ulong) (full_size * (file_ptrs.elements + 1)))
+    res= merge(table, merge_buffer, buff_sz >= full_size * MERGEBUFF2) ;
+  
+  if (!res)
+  {  
+    res= merge_walk(merge_buffer, (ulong) max_in_memory_size, full_size,
+                    (BUFFPEK *) file_ptrs.buffer,
+                    (BUFFPEK *) file_ptrs.buffer + file_ptrs.elements,
+                    action, walk_action_arg,
+                    tree.compare, tree.custom_arg, &file);
+  }
   my_free(merge_buffer);
   return res;
 }
 
+
 /*
-  Modify the TABLE element so that when one calls init_records()
-  the rows will be read in priority order.
-*/
+  DESCRIPTION
+    Perform multi-pass sort merge of the elements accessed through table->sort,
+    using the buffer buff as the merge buffer. The last pass is not performed
+    if without_last_merge is TRUE.
+  SYNOPSIS
+    Unique:merge()
+  All params are 'IN':
+    table               the parameter to access sort context
+    buff                merge buffer
+    without_last_merge  TRUE <=> do not perform the last merge
+  RETURN VALUE
+    0    OK
+    <> 0 error
+ */
 
-bool Unique::get(TABLE *table)
+bool Unique::merge(TABLE *table, uchar *buff, bool without_last_merge)
 {
   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 */
-    DBUG_ASSERT(table->sort.record_pointers == NULL);
-    if ((record_pointers=table->sort.record_pointers= (uchar*)
-	 my_malloc(size * tree.elements_in_tree, MYF(0))))
-    {
-      tree_walk_action action= min_dupl_count ?
-		         (tree_walk_action) unique_intersect_write_to_ptrs :
-		         (tree_walk_action) unique_write_to_ptrs;
-      filtered_out_elems= 0;
-      (void) tree_walk(&tree, action,
-		       this, left_root_right);
-      table->sort.found_records-= filtered_out_elems;
-      return 0;
-    }
-  }
-  /* Not enough memory; Save the result to file && free memory used by tree */
-  if (flush())
-    return 1;
-
-  IO_CACHE *outfile=table->sort.io_cache;
+  IO_CACHE *outfile= table->sort.io_cache;
   BUFFPEK *file_ptr= (BUFFPEK*) file_ptrs.buffer;
   uint maxbuffer= file_ptrs.elements - 1;
-  uchar *sort_buffer;
   my_off_t save_pos;
-  bool error=1;
-
-      /* Open cached file if it isn't open */
-  DBUG_ASSERT(table->sort.io_cache == NULL);
-  outfile=table->sort.io_cache=(IO_CACHE*) my_malloc(sizeof(IO_CACHE),
-                                MYF(MY_ZEROFILL));
+  bool error= 1;
 
+  /* Open cached file if it isn't open */
+  if (!outfile)
+    outfile= table->sort.io_cache= (IO_CACHE*) my_malloc(sizeof(IO_CACHE),
+                                                         MYF(MY_ZEROFILL));
   if (!outfile ||
       (! my_b_inited(outfile) &&
        open_cached_file(outfile,mysql_tmpdir,TEMP_PREFIX,READ_RECORD_BUFFER,
@@ -667,47 +664,89 @@ bool Unique::get(TABLE *table)
 
   bzero((char*) &sort_param,sizeof(sort_param));
   sort_param.max_rows= elements;
-  sort_param.sort_form=table;
+  sort_param.sort_form= table;
   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;
+  sort_param.not_killable= 1;
 
-  if (!(sort_buffer=(uchar*) my_malloc((sort_param.keys+1) *
-				       sort_param.sort_length,
-				       MYF(0))))
-    return 1;
-  sort_param.unique_buff= sort_buffer+(sort_param.keys*
-				       sort_param.sort_length);
+  sort_param.unique_buff= buff + (sort_param.keys * sort_param.sort_length);
 
   sort_param.compare= (qsort2_cmp) buffpek_compare;
   sort_param.cmp_context.key_compare= tree.compare;
   sort_param.cmp_context.key_compare_arg= tree.custom_arg;
 
   /* Merge the buffers to one file, removing duplicates */
-  if (merge_many_buff(&sort_param,sort_buffer,file_ptr,&maxbuffer,&file))
+  if (merge_many_buff(&sort_param,buff,file_ptr,&maxbuffer,&file))
     goto err;
   if (flush_io_cache(&file) ||
       reinit_io_cache(&file,READ_CACHE,0L,0,0))
     goto err;
   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))
+  if (without_last_merge)
+  {
+    file_ptrs.elements= maxbuffer+1;
+    return 0;
+  }
+  if (merge_index(&sort_param, buff, file_ptr, maxbuffer, &file, outfile))
     goto err;
-  error=0;
+  error= 0;
 err:
-  my_free(sort_buffer);
   if (flush_io_cache(outfile))
-    error=1;
+    error= 1;
 
   /* Setup io_cache for reading */
-  save_pos=outfile->pos_in_file;
+  save_pos= outfile->pos_in_file;
   if (reinit_io_cache(outfile,READ_CACHE,0L,0,0))
-    error=1;
+    error= 1;
   outfile->end_of_file=save_pos;
   return error;
 }
 
 
+/*
+  Modify the TABLE element so that when one calls init_records()
+  the rows will be read in priority order.
+*/
+
+bool Unique::get(TABLE *table)
+{
+  bool rc= 1;
+  uchar *sort_buffer= NULL;
+  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))))
+    {
+      tree_walk_action action= min_dupl_count ?
+		         (tree_walk_action) unique_intersect_write_to_ptrs :
+		         (tree_walk_action) unique_write_to_ptrs;
+      filtered_out_elems= 0;
+      (void) tree_walk(&tree, action,
+		       this, left_root_right);
+      table->sort.found_records-= filtered_out_elems;
+      return 0;
+    }
+  }
+  /* Not enough memory; Save the result to file && free memory used by tree */
+  if (flush())
+    return 1;
+  
+  ulong buff_sz= (max_in_memory_size / full_size + 1) * full_size;
+  if (!(sort_buffer= (uchar*) my_malloc(buff_sz, MYF(0))))
+    return 1;
+
+  if (merge(table, sort_buffer, FALSE))
+    goto err;  
+  rc= 0;  
+
+err:  
+  my_free(sort_buffer);  
+  return rc;
+}