diff --git a/mysql-test/r/statistics.result b/mysql-test/r/statistics.result
index e3f4d6bf564..ba0390f98db 100644
--- a/mysql-test/r/statistics.result
+++ b/mysql-test/r/statistics.result
@@ -499,14 +499,9 @@ test	t1	f	1	5	0.2000	1.0000	6.4000
 SELECT * FROM mysql.index_stats;
 db_name	table_name	index_name	prefix_arity	avg_frequency
 test	t1	PRIMARY	1	1.0000
-test	t1	idx1	1	6.4000
-test	t1	idx1	2	1.6875
 test	t1	idx2	1	7.0000
 test	t1	idx2	2	2.3846
 test	t1	idx3	1	8.5000
-test	t1	idx4	1	6.2000
-test	t1	idx4	2	1.6875
-test	t1	idx4	3	1.1304
 ALTER TABLE t1 CHANGE COLUMN x b varchar(32);
 SHOW CREATE TABLE t1;
 Table	Create Table
@@ -590,14 +585,9 @@ test	t1	f	1	5	0.2000	1.0000	6.4000
 SELECT * FROM mysql.index_stats;
 db_name	table_name	index_name	prefix_arity	avg_frequency
 test	t1	PRIMARY	1	1.0000
-test	t1	idx4	3	1.1304
-test	t1	idx4	2	1.6875
 test	t1	idx2	1	7.0000
 test	t1	idx2	2	2.3846
 test	t1	idx3	1	8.5000
-test	t1	idx4	1	6.2000
-test	t1	idx1	2	1.6875
-test	t1	idx1	1	6.4000
 ALTER TABLE t1 CHANGE COLUMN x b varchar(32);
 SHOW CREATE TABLE t1;
 Table	Create Table
@@ -943,6 +933,7 @@ test	t1	idx4	3	1.1304
 CREATE TABLE t2 LIKE t1;
 ALTER TABLE t2 ENGINE=InnoDB;
 INSERT INTO t2 SELECT * FROM t1;
+set optimizer_switch='extended_keys=off';
 ANALYZE TABLE t2;
 Table	Op	Msg_type	Msg_text
 test.t2	analyze	status	OK
@@ -987,6 +978,142 @@ test	t2	idx4	3	1.1304
 DELETE FROM mysql.table_stats;
 DELETE FROM mysql.column_stats;
 DELETE FROM mysql.index_stats;
+set optimizer_switch='extended_keys=on';
+ANALYZE TABLE t2;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	OK
+SELECT * FROM mysql.table_stats;
+db_name	table_name	cardinality
+test	t2	40
+SELECT * FROM mysql.column_stats ORDER BY column_name;
+db_name	table_name	column_name	min_value	max_value	nulls_ratio	avg_length	avg_frequency
+test	t2	a	0	49	0.0000	4.0000	1.0000
+test	t2	b	vvvvvvvvvvvvv	zzzzzzzzzzzzzzzzzz	0.2000	17.1250	6.4000
+test	t2	c	aaaa	dddddddd	0.1250	6.6571	7.0000
+test	t2	d	1989-03-12	1999-07-23	0.1500	3.0000	8.5000
+test	t2	e	0.01	0.112	0.2250	8.0000	6.2000
+test	t2	f	1	5	0.2000	1.0000	6.4000
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	PRIMARY	1	1.0000
+test	t2	idx1	1	6.4000
+test	t2	idx1	2	1.6875
+test	t2	idx1	3	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx2	3	1.0000
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	1.6875
+test	t2	idx4	3	1.1304
+test	t2	idx4	4	1.0000
+ALTER TABLE t2 DROP PRIMARY KEY, DROP INDEX idx1;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx3	1	8.5000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	1.6875
+test	t2	idx4	3	1.1304
+UPDATE t2 SET b=0 WHERE b IS NULL;
+ALTER TABLE t2 ADD PRIMARY KEY (a,b);
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx3	1	8.5000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	1.6875
+test	t2	idx4	3	1.1304
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS() INDEXES ALL;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	OK
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	PRIMARY	1	1.0000
+test	t2	PRIMARY	2	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx2	3	1.0000
+test	t2	idx2	4	1.0000
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx3	3	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	1.7222
+test	t2	idx4	3	1.1154
+test	t2	idx4	4	1.0000
+ALTER TABLE t2 CHANGE COLUMN b b varchar(30);
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx3	1	8.5000
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS ALL INDEXES ALL;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	OK
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	PRIMARY	1	1.0000
+test	t2	PRIMARY	2	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx2	3	1.0000
+test	t2	idx2	4	1.0000
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx3	3	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	1.7222
+test	t2	idx4	3	1.1154
+test	t2	idx4	4	1.0000
+ALTER TABLE t2 CHANGE COLUMN b b varchar(32);
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx3	1	8.5000
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS ALL INDEXES ALL;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	OK
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	PRIMARY	1	1.0000
+test	t2	PRIMARY	2	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx2	3	1.0000
+test	t2	idx2	4	1.0000
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx3	3	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	1.7222
+test	t2	idx4	3	1.1154
+test	t2	idx4	4	1.0000
+ALTER TABLE t2 DROP COLUMN b;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx3	1	8.5000
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS() INDEXES ALL;
+Table	Op	Msg_type	Msg_text
+test.t2	analyze	status	OK
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	PRIMARY	1	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx2	3	1.0000
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	2.2308
+test	t2	idx4	3	1.0000
+set optimizer_switch='extended_keys=off';
 ALTER TABLE t1
 DROP INDEX idx1,
 DROP INDEX idx4;
@@ -994,11 +1121,34 @@ ALTER TABLE t1
 MODIFY COLUMN b text,
 ADD INDEX idx1 (b(4), e), 
 ADD INDEX idx4 (e, b(4), d);
+SELECT * FROM mysql.column_stats;
+db_name	table_name	column_name	min_value	max_value	nulls_ratio	avg_length	avg_frequency
+test	t2	a	0	49	0.0000	4.0000	1.0000
+test	t2	c	aaaa	dddddddd	0.1250	6.6571	7.0000
+test	t2	d	1989-03-12	1999-07-23	0.1500	3.0000	8.5000
+test	t2	e	0.01	0.112	0.2250	8.0000	6.2000
+test	t2	f	1	5	0.2000	1.0000	6.4000
+SELECT * FROM mysql.index_stats;
+db_name	table_name	index_name	prefix_arity	avg_frequency
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx2	3	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
+test	t2	idx4	3	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	2.2308
+test	t2	PRIMARY	1	1.0000
 ANALYZE TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	analyze	status	OK
 SELECT * FROM mysql.column_stats;
 db_name	table_name	column_name	min_value	max_value	nulls_ratio	avg_length	avg_frequency
+test	t2	a	0	49	0.0000	4.0000	1.0000
+test	t2	c	aaaa	dddddddd	0.1250	6.6571	7.0000
+test	t2	d	1989-03-12	1999-07-23	0.1500	3.0000	8.5000
+test	t2	e	0.01	0.112	0.2250	8.0000	6.2000
+test	t2	f	1	5	0.2000	1.0000	6.4000
 test	t1	a	0	49	0.0000	4.0000	1.0000
 test	t1	c	aaaa	dddddddd	0.1250	6.6571	7.0000
 test	t1	d	1989-03-12	1999-07-23	0.1500	3.0000	8.5000
@@ -1007,9 +1157,18 @@ test	t1	f	1	5	0.2000	1.0000	6.4000
 test	t1	b	NULL	NULL	0.2000	17.1250	NULL
 SELECT * FROM mysql.index_stats;
 db_name	table_name	index_name	prefix_arity	avg_frequency
-test	t1	PRIMARY	1	1.0000
-test	t1	idx3	1	8.5000
+test	t2	idx3	1	8.5000
+test	t2	idx3	2	1.0000
+test	t2	idx2	3	1.0000
+test	t2	idx2	1	7.0000
+test	t2	idx2	2	2.3846
 test	t1	idx2	1	7.0000
+test	t1	idx3	1	8.5000
+test	t1	PRIMARY	1	1.0000
+test	t2	idx4	3	1.0000
+test	t2	idx4	1	6.2000
+test	t2	idx4	2	2.2308
+test	t2	PRIMARY	1	1.0000
 test	t1	idx2	2	2.3846
 test	t1	idx1	1	NULL
 test	t1	idx1	2	NULL
@@ -1057,28 +1216,6 @@ test	t1	idx1	2	NULL
 test	t1	idx4	1	6.2000
 test	t1	idx4	2	NULL
 test	t1	idx4	3	NULL
-SELECT * FROM mysql.table_stats;
-db_name	table_name	cardinality
-test	t1	40
-SELECT * FROM mysql.column_stats;
-db_name	table_name	column_name	min_value	max_value	nulls_ratio	avg_length	avg_frequency
-test	t1	a	0	49	0.0000	4.0000	1.0000
-test	t1	c	aaaa	dddddddd	0.1250	6.6571	7.0000
-test	t1	d	1989-03-12	1999-07-23	0.1500	3.0000	8.5000
-test	t1	e	0.01	0.112	0.2250	8.0000	6.2000
-test	t1	f	1	5	0.2000	1.0000	6.4000
-test	t1	b	NULL	NULL	0.2000	17.1250	NULL
-SELECT * FROM mysql.index_stats;
-db_name	table_name	index_name	prefix_arity	avg_frequency
-test	t1	PRIMARY	1	1.0000
-test	t1	idx3	1	8.5000
-test	t1	idx2	1	7.0000
-test	t1	idx2	2	2.3846
-test	t1	idx1	1	NULL
-test	t1	idx1	2	NULL
-test	t1	idx4	1	6.2000
-test	t1	idx4	2	NULL
-test	t1	idx4	3	NULL
 DELETE FROM mysql.table_stats;
 DELETE FROM mysql.column_stats;
 DELETE FROM mysql.index_stats;
diff --git a/mysql-test/t/mdev-504.test b/mysql-test/t/mdev-504.test
index 5193581cc47..bc38e99067a 100644
--- a/mysql-test/t/mdev-504.test
+++ b/mysql-test/t/mdev-504.test
@@ -1,3 +1,5 @@
+--disable_ps_protocol
+
 CREATE TABLE A (
   pk INTEGER AUTO_INCREMENT PRIMARY KEY,
   fdate DATE
diff --git a/mysql-test/t/statistics.test b/mysql-test/t/statistics.test
index 4537c4ed3f3..4f2d0510c11 100644
--- a/mysql-test/t/statistics.test
+++ b/mysql-test/t/statistics.test
@@ -368,22 +368,60 @@ SELECT * FROM mysql.table_stats;
 SELECT * FROM mysql.column_stats;
 SELECT * FROM mysql.index_stats;
 
-
 CREATE TABLE t2 LIKE t1;
 ALTER TABLE t2 ENGINE=InnoDB;
 INSERT INTO t2 SELECT * FROM t1;
 
+set optimizer_switch='extended_keys=off';
+
 ANALYZE TABLE t2;
 
 SELECT * FROM mysql.table_stats;
 SELECT * FROM mysql.column_stats ORDER BY column_name;
 SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
 
-
 DELETE FROM mysql.table_stats;
 DELETE FROM mysql.column_stats;
 DELETE FROM mysql.index_stats;
 
+set optimizer_switch='extended_keys=on';
+
+ANALYZE TABLE t2;
+
+SELECT * FROM mysql.table_stats;
+SELECT * FROM mysql.column_stats ORDER BY column_name;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ALTER TABLE t2 DROP PRIMARY KEY, DROP INDEX idx1;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+UPDATE t2 SET b=0 WHERE b IS NULL;
+ALTER TABLE t2 ADD PRIMARY KEY (a,b);
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS() INDEXES ALL;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ALTER TABLE t2 CHANGE COLUMN b b varchar(30);
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS ALL INDEXES ALL;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ALTER TABLE t2 CHANGE COLUMN b b varchar(32);
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS ALL INDEXES ALL;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ALTER TABLE t2 DROP COLUMN b;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+ANALYZE TABLE t2 PERSISTENT FOR COLUMNS() INDEXES ALL;
+SELECT * FROM mysql.index_stats ORDER BY index_name, prefix_arity, table_name;
+
+set optimizer_switch='extended_keys=off';
+
 ALTER TABLE t1
   DROP INDEX idx1,
   DROP INDEX idx4;
@@ -392,6 +430,9 @@ ALTER TABLE t1
   ADD INDEX idx1 (b(4), e), 
   ADD INDEX idx4 (e, b(4), d);
   
+SELECT * FROM mysql.column_stats;
+SELECT * FROM mysql.index_stats;
+
 ANALYZE TABLE t1;
 
 SELECT * FROM mysql.column_stats;
@@ -411,7 +452,6 @@ SELECT * FROM mysql.index_stats;
 
 set use_stat_tables='never';  
 
-
 ANALYZE TABLE t1 PERSISTENT FOR ALL;
 
 SELECT * FROM mysql.table_stats;
@@ -419,11 +459,6 @@ SELECT * FROM mysql.column_stats;
 SELECT * FROM mysql.index_stats;
 
 
-SELECT * FROM mysql.table_stats;
-SELECT * FROM mysql.column_stats;
-SELECT * FROM mysql.index_stats;
-
-
 DELETE FROM mysql.table_stats;
 DELETE FROM mysql.column_stats;
 DELETE FROM mysql.index_stats;
diff --git a/sql/sql_base.h b/sql/sql_base.h
index 71b4a9289ce..d45652927de 100644
--- a/sql/sql_base.h
+++ b/sql/sql_base.h
@@ -321,7 +321,8 @@ int alloc_statistics_for_table(THD *thd, TABLE *table);
 int update_statistics_for_table(THD *thd, TABLE *table);
 int delete_statistics_for_table(THD *thd, LEX_STRING *db, LEX_STRING *tab);
 int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col);
-int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info);
+int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info,
+                                bool ext_prefixes_only);
 int rename_table_in_stat_tables(THD *thd, LEX_STRING *db, LEX_STRING *tab,
                                 LEX_STRING *new_db, LEX_STRING *new_tab);
 int rename_column_in_stat_tables(THD *thd, TABLE *tab, Field *col,
diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
index ce925a8fe96..f8f1175ac28 100644
--- a/sql/sql_statistics.cc
+++ b/sql/sql_statistics.cc
@@ -2660,6 +2660,9 @@ int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col)
   tab         The table the index belongs to
   @param
   key_info    The descriptor of the index whose statistics is to be deleted
+  @param
+  ext_prefixes_only  Delete statistics only on the index prefixes extended by
+                     the components of the primary key 
 
   @details
   The function delete statistics on the index  specified by 'key_info'
@@ -2675,7 +2678,8 @@ int delete_statistics_for_column(THD *thd, TABLE *tab, Field *col)
    definition of a column used in the definition of the index. 
 */
 
-int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info)
+int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info,
+                                bool ext_prefixes_only)
 {
   int err;
   bool save_binlog_row_based;
@@ -2702,14 +2706,29 @@ int delete_statistics_for_index(THD *thd, TABLE *tab, KEY *key_info)
 
   stat_table= tables.table;
   Index_stat index_stat(stat_table, tab);
-  index_stat.set_index_prefix_key_fields(key_info);
-  while (index_stat.find_next_stat_for_prefix(3))
+  if (!ext_prefixes_only)
   {
-    err= index_stat.delete_stat();
-    if (err && !rc)
-      rc= 1;
+    index_stat.set_index_prefix_key_fields(key_info);
+    while (index_stat.find_next_stat_for_prefix(3))
+    {
+      err= index_stat.delete_stat();
+      if (err && !rc)
+        rc= 1;
+    }
+  }
+  else
+  {
+    for (uint i= key_info->key_parts; i < key_info->ext_key_parts; i++)
+    {
+      index_stat.set_key_fields(key_info, i+1);
+      if (index_stat.find_next_stat_for_prefix(4))
+      {
+        err= index_stat.delete_stat();
+        if (err && !rc)
+          rc= 1;
+      }
+    }
   }
-
   if (save_binlog_row_based)
     thd->set_current_stmt_binlog_format_row();
 
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index eb2a52e426c..b63c1859582 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -5243,6 +5243,26 @@ mysql_compare_tables(TABLE *table,
     /* Evaluate changes bitmap and send to check_if_incompatible_data() */
     if (!(tmp= field->is_equal(tmp_new_field)))
     {
+      if (table->s->tmp_table == NO_TMP_TABLE)
+      {
+        KEY *key_info= table->key_info; 
+	for (uint i=0; i < table->s->keys; i++, key_info++)
+	{
+          if (field->part_of_key.is_set(i))
+	  {
+            uint key_parts= table->actual_n_key_parts(key_info);
+            for (uint j= 0; j < key_parts; j++)
+	    {
+              if (key_info->key_part[j].fieldnr-1 == field->field_index)
+	      {
+                (void) delete_statistics_for_index(thd, table, key_info,
+                                                   j >= key_info->key_parts);
+                break;
+	      }
+            }           
+          }
+        }      
+      }
       DBUG_PRINT("info", ("!field_is_equal('%s') -> ALTER_TABLE_DATA_CHANGED",
                           new_field->field_name));
       DBUG_RETURN(0);
@@ -5342,7 +5362,20 @@ mysql_compare_tables(TABLE *table,
       field->flags|= FIELD_IN_ADD_INDEX;
     }
     if (table->s->tmp_table == NO_TMP_TABLE)
-      (void) delete_statistics_for_index(thd, table, table_key);
+    {
+      (void) delete_statistics_for_index(thd, table, table_key, FALSE);
+      if (table_key - table->key_info == table->s->primary_key)
+      {
+        KEY *tab_key_info= table->key_info;
+	for (uint j=0; j < table->s->keys; j++, tab_key_info++)
+	{
+          if (tab_key_info->key_parts != tab_key_info->ext_key_parts)
+	    (void) delete_statistics_for_index(thd, table, tab_key_info,
+                                               TRUE);
+	}
+      }
+    }
+
     DBUG_PRINT("info", ("index changed: '%s'", table_key->name));
   }
   /*end of for (; table_key < table_key_end;) */
@@ -5544,6 +5577,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
   uint used_fields= create_info->used_fields;
   KEY *key_info=table->key_info;
   bool rc= TRUE;
+  bool modified_primary_key= FALSE;
   Create_field *def;
   Field **f_ptr,*field;
   DBUG_ENTER("mysql_prepare_alter_table");
@@ -5740,7 +5774,7 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
     Collect all keys which isn't in drop list. Add only those
     for which some fields exists.
   */
-
+ 
   for (uint i=0 ; i < table->s->keys ; i++,key_info++)
   {
     char *key_name= key_info->name;
@@ -5755,7 +5789,19 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
     if (drop)
     {
       if (table->s->tmp_table == NO_TMP_TABLE)
-        (void) delete_statistics_for_index(thd, table, key_info);
+      {
+        (void) delete_statistics_for_index(thd, table, key_info, FALSE);
+        if (i == table->s->primary_key)
+	{
+          KEY *tab_key_info= table->key_info;
+	  for (uint j=0; j < table->s->keys; j++, tab_key_info++)
+	  {
+            if (tab_key_info->key_parts != tab_key_info->ext_key_parts)
+	      (void) delete_statistics_for_index(thd, table, tab_key_info,
+                                                 TRUE);
+	  }
+	}
+      }  
       drop_it.remove();
       continue;
     }
@@ -5786,6 +5832,8 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
       }
       if (!cfield)
       {
+        if (table->s->primary_key == i)
+          modified_primary_key= TRUE;
         delete_index_stat= TRUE;
 	continue;				// Field is removed
       }
@@ -5830,8 +5878,15 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
                                             strlen(cfield->field_name),
 					    key_part_length));
     }
-    if (delete_index_stat && table->s->tmp_table == NO_TMP_TABLE)
-      (void) delete_statistics_for_index(thd, table, key_info);
+    if (table->s->tmp_table == NO_TMP_TABLE)
+    {
+      if (delete_index_stat) 
+        (void) delete_statistics_for_index(thd, table, key_info, FALSE);
+      else if (modified_primary_key &&
+               key_info->key_parts != key_info->ext_key_parts)
+        (void) delete_statistics_for_index(thd, table, key_info, TRUE);
+    }
+
     if (key_parts.elements)
     {
       KEY_CREATE_INFO key_create_info;