Don't count NULL values in cardinalty for MyISAM tables.

Free row buffer cache after each query for MyISAM tables.
Added table join option FORCE INDEX
Fixed core dump bug when connecting with hostname that could not be resolved.


include/my_base.h:
  Don't count NULL values in cardinalty
myisam/mi_check.c:
  Don't count NULL values in cardinalty
myisam/mi_extra.c:
  Free row buffer cache after each query
myisam/mi_open.c:
  Avoid realloc if cache size doesn't change
myisam/mi_search.c:
  Don't count NULL values in cardinalty
myisam/myisamdef.h:
  Change buffer length from uint to uint32 to make it more portable/predictable
mysql-test/r/myisam.result:
  Test case for cardinality with NULL keys and FORCE INDEX
mysql-test/t/myisam.test:
  Test case for cardinality with NULL keys and FORCE INDEX
sql/lex.h:
  Added table join option FORCE INDEX
sql/mysql_priv.h:
  Added table join option FORCE INDEX
sql/opt_range.cc:
  Added table join option FORCE INDEX
sql/sql_base.cc:
  Added table join option FORCE INDEX
sql/sql_lex.h:
  Added table join option FORCE INDEX
sql/sql_parse.cc:
  Added table join option FORCE INDEX
  Don't use strlen() on hostname without first checking if it's not NULL
sql/sql_select.cc:
  Added table join option FORCE INDEX
sql/sql_yacc.yy:
  Added table join option FORCE INDEX
sql/table.h:
  Added table join option FORCE INDEX

include/my_base.h

@@ -263,6 +263,7 @@ enum ha_base_keytype {
 #define MBR_EQUAL       8192
 #define MBR_DATA        16384
 #define SEARCH_NULL_ARE_EQUAL 32768	/* NULL in keys are equal */
+#define SEARCH_NULL_ARE_NOT_EQUAL 65536	/* NULL in keys are not equal */
 
 	/* bits in opt_flag */
 #define QUICK_USED	1

myisam/mi_check.c

@@ -601,7 +601,8 @@ static int chk_index(MI_CHECK *param, MI_INFO *info, MI_KEYDEF *keyinfo,
       if (*keys != 1L)				/* not first_key */
       {
 	uint diff;
-	_mi_key_cmp(keyinfo->seg,info->lastkey,key,USE_WHOLE_KEY,SEARCH_FIND,
+	_mi_key_cmp(keyinfo->seg,info->lastkey,key,USE_WHOLE_KEY,
+		    SEARCH_FIND | SEARCH_NULL_ARE_NOT_EQUAL,
 		    &diff);
 	param->unique_count[diff-1]++;
       }

myisam/mi_extra.c

@@ -55,12 +55,17 @@ int mi_extra(MI_INFO *info, enum ha_extra_function function, void *extra_arg)
     /*
       Free buffers and reset the following flags:
       EXTRA_CACHE, EXTRA_WRITE_CACHE, EXTRA_KEYREAD, EXTRA_QUICK
+
+      If the row buffer cache is large (for dynamic tables), reduce it
+      to save memory.
     */
     if (info->opt_flag & (READ_CACHE_USED | WRITE_CACHE_USED))
     {
       info->opt_flag&= ~(READ_CACHE_USED | WRITE_CACHE_USED);
       error=end_io_cache(&info->rec_cache);
     }
+    if (share->base.blobs)
+      mi_alloc_rec_buff(info, -1, &info->rec_buff);
 #if defined(HAVE_MMAP) && defined(HAVE_MADVICE)
     if (info->opt_flag & MEMMAP_USED)
       madvise(share->file_map,share->state.state.data_file_length,MADV_RANDOM);

myisam/mi_open.c

@@ -559,28 +559,36 @@ err:
   DBUG_RETURN (NULL);
 } /* mi_open */
 
+
 byte *mi_alloc_rec_buff(MI_INFO *info, ulong length, byte **buf)
 {
   uint extra;
+  uint32 old_length;
+  LINT_INIT(old_length);
 
-  if (! *buf || length > mi_get_rec_buff_len(info, *buf))
+  if (! *buf || length > (old_length=mi_get_rec_buff_len(info, *buf)))
   {
     byte *newptr = *buf;
 
     /* to simplify initial init of info->rec_buf in mi_open and mi_extra */
     if (length == (ulong) -1)
+    {
       length= max(info->s->base.pack_reclength+info->s->base.pack_bits,
                   info->s->base.max_key_length);
+      /* Avoid unnecessary realloc */
+      if (newptr && length == old_length)
+	return newptr;
+    }
 
     extra= ((info->s->options & HA_OPTION_PACK_RECORD) ?
 	    ALIGN_SIZE(MI_MAX_DYN_BLOCK_HEADER)+MI_SPLIT_LENGTH+
 	    MI_REC_BUFF_OFFSET : 0);
     if (extra && newptr)
-      newptr-=MI_REC_BUFF_OFFSET;
+      newptr-= MI_REC_BUFF_OFFSET;
     if (!(newptr=(byte*) my_realloc((gptr)newptr, length+extra+8,
                                      MYF(MY_ALLOW_ZERO_PTR))))
       return newptr;
-    *((uint *)newptr)=length;
+    *((uint32 *) newptr)= (uint32) length;
     *buf= newptr+(extra ?  MI_REC_BUFF_OFFSET : 0);
   }
   return *buf;

myisam/mi_search.c

@@ -260,9 +260,11 @@ int _mi_prefix_search(MI_INFO *info, register MI_KEYDEF *keyinfo, uchar *page,
                       uchar *key, uint key_len, uint nextflag, uchar **ret_pos,
                       uchar *buff, my_bool *last_key)
 {
-  /* my_flag is raw comparison result to be changed according to
-     SEARCH_NO_FIND,SEARCH_LAST and HA_REVERSE_SORT flags.
-     flag is the value returned by _mi_key_cmp and as treated as final */
+  /*
+    my_flag is raw comparison result to be changed according to
+    SEARCH_NO_FIND,SEARCH_LAST and HA_REVERSE_SORT flags.
+    flag is the value returned by _mi_key_cmp and as treated as final
+  */
   int flag=0, my_flag=-1;
   uint nod_flag, length, len, matched, cmplen, kseg_len;
   uint prefix_len,suffix_len;
@@ -695,13 +697,29 @@ static int compare_bin(uchar *a, uint a_length, uchar *b, uint b_length,
 }
 
 
-        /*
-        ** Compare two keys
-        ** Returns <0, 0, >0 acording to which is bigger
-        ** Key_length specifies length of key to use.  Number-keys can't
-        ** be splited
-        ** If flag <> SEARCH_FIND compare also position
-        */
+/*
+  Compare two keys
+
+  SYNOPSIS
+    _mi_key_cmp()
+    keyseg	Key segments of key to compare
+    a		First key to compare, in format from _mi_pack_key()
+		This is normally key specified by user
+    b		Second key to compare.  This is always from a row
+    key_length	Length of key to compare.  This can be shorter than
+		a to just compare sub keys
+    next_flag	How keys should be compared
+		If bit SEARCH_FIND is not set the keys includes the row
+		position and this should also be compared
+
+  NOTES
+    Number-keys can't be splited
+  
+  RETURN VALUES
+    <0	If a < b
+    0	If a == b
+    >0	If a > b
+*/
 
 #define FCMP(A,B) ((int) (A) - (int) (B))
 
@@ -738,6 +756,15 @@ int _mi_key_cmp(register MI_KEYSEG *keyseg, register uchar *a,
       {
         if (nextflag == (SEARCH_FIND | SEARCH_UPDATE))
           nextflag=SEARCH_SAME;                 /* Allow duplicate keys */
+	else if (nextflag & SEARCH_NULL_ARE_NOT_EQUAL)
+	{
+	  /*
+	    This is only used from mi_check() to calculate cardinality.
+	    It can't be used when searching for a key as this would cause
+	    compare of (a,b) and (b,a) to return the same value.
+	  */
+	  return -1;
+	}
         next_key_length=key_length;
         continue;                               /* To next key part */
       }

myisam/myisamdef.h

@@ -358,7 +358,7 @@ struct st_myisam_info {
 #define MI_DYN_ALIGN_SIZE	4	/* Align blocks on this */
 #define MI_MAX_DYN_HEADER_BYTE	13	/* max header byte for dynamic rows */
 #define MI_MAX_BLOCK_LENGTH	((((ulong) 1 << 24)-1) & (~ (ulong) (MI_DYN_ALIGN_SIZE-1)))
-#define MI_REC_BUFF_OFFSET      ALIGN_SIZE(MI_DYN_DELETE_BLOCK_HEADER+sizeof(uint))
+#define MI_REC_BUFF_OFFSET      ALIGN_SIZE(MI_DYN_DELETE_BLOCK_HEADER+sizeof(uint32))
 
 #define MEMMAP_EXTRA_MARGIN	7	/* Write this as a suffix for file */
 
@@ -529,7 +529,7 @@ extern byte *mi_alloc_rec_buff(MI_INFO *,ulong, byte**);
         ((((info)->s->options & HA_OPTION_PACK_RECORD) && (buf)) ? \
         (buf) - MI_REC_BUFF_OFFSET : (buf))
 #define mi_get_rec_buff_len(info,buf)                              \
-        (*((uint *)(mi_get_rec_buff_ptr(info,buf))))
+        (*((uint32 *)(mi_get_rec_buff_ptr(info,buf))))
 
 extern ulong _mi_rec_unpack(MI_INFO *info,byte *to,byte *from,
 			    ulong reclength);

mysql-test/r/myisam.result

-drop table if exists t1;
+drop table if exists t1,t2;
 CREATE TABLE t1 (
 STRING_DATA char(255) default NULL,
 KEY STRING_DATA (STRING_DATA)
@@ -318,3 +318,45 @@ CREATE TABLE t1 (a varchar(255), b varchar(255), c varchar(255));
 ALTER TABLE t1 ADD INDEX t1 (a, b, c);
 Specified key was too long. Max key length is 500
 DROP TABLE t1;
+CREATE TABLE t1 (a int not null, b int, c int, key(b), key(c), key(a,b), key(c,a));
+INSERT into t1 values (0, null, 0), (0, null, 1), (0, null, 2), (0, null,3), (1,1,4);
+create table t2 (a int not null, b int, c int, key(b), key(c), key(a));
+INSERT into t2 values (1,1,1), (2,2,2);
+optimize table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	optimize	status	OK
+show index from t1;
+Table	Non_unique	Key_name	Seq_in_index	Column_name	Collation	Cardinality	Sub_part	Packed	Null	Index_type	Comment
+t1	1	b	1	b	A	5	NULL	NULL	YES	BTREE	
+t1	1	c	1	c	A	5	NULL	NULL	YES	BTREE	
+t1	1	a	1	a	A	1	NULL	NULL		BTREE	
+t1	1	a	2	b	A	5	NULL	NULL	YES	BTREE	
+t1	1	c_2	1	c	A	5	NULL	NULL	YES	BTREE	
+t1	1	c_2	2	a	A	5	NULL	NULL		BTREE	
+explain select * from t1,t2 where t1.a=t2.a;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ALL	a	NULL	NULL	NULL	5	
+t2	ALL	a	NULL	NULL	NULL	2	Using where
+explain select * from t1,t2 force index(a) where t1.a=t2.a;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t2	ALL	a	NULL	NULL	NULL	2	
+t1	ALL	a	NULL	NULL	NULL	5	Using where
+explain select * from t1 force index(a),t2 force index(a) where t1.a=t2.a;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t2	ALL	a	NULL	NULL	NULL	2	
+t1	ref	a	a	4	t2.a	3	
+explain select * from t1,t2 where t1.b=t2.b;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t2	ALL	b	NULL	NULL	NULL	2	
+t1	ref	b	b	5	t2.b	1	Using where
+explain select * from t1,t2 force index(c) where t1.a=t2.a;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ALL	a	NULL	NULL	NULL	5	
+t2	ALL	NULL	NULL	NULL	NULL	2	Using where
+explain select * from t1 where a=0 or a=2;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	ALL	a	NULL	NULL	NULL	5	Using where
+explain select * from t1 force index (a) where a=0 or a=2;
+table	type	possible_keys	key	key_len	ref	rows	Extra
+t1	range	a	a	4	NULL	4	Using where
+drop table t1,t2;

mysql-test/t/myisam.test

@@ -2,7 +2,13 @@
 # Test bugs in the MyISAM code
 #
 
-drop table if exists t1;
+# Initialise
+drop table if exists t1,t2;
+
+#
+# Test problem with CHECK TABLE;
+#
+
 CREATE TABLE t1 (
   STRING_DATA char(255) default NULL,
   KEY STRING_DATA (STRING_DATA)
@@ -326,3 +332,21 @@ CREATE TABLE t1 (a varchar(255), b varchar(255), c varchar(255));
 ALTER TABLE t1 ADD INDEX t1 (a, b, c);   
 DROP TABLE t1;
 
+#
+# Test of cardinality of keys with NULL
+#
+
+CREATE TABLE t1 (a int not null, b int, c int, key(b), key(c), key(a,b), key(c,a));
+INSERT into t1 values (0, null, 0), (0, null, 1), (0, null, 2), (0, null,3), (1,1,4);
+create table t2 (a int not null, b int, c int, key(b), key(c), key(a));
+INSERT into t2 values (1,1,1), (2,2,2);
+optimize table t1;
+show index from t1;
+explain select * from t1,t2 where t1.a=t2.a;
+explain select * from t1,t2 force index(a) where t1.a=t2.a;
+explain select * from t1 force index(a),t2 force index(a) where t1.a=t2.a;
+explain select * from t1,t2 where t1.b=t2.b;
+explain select * from t1,t2 force index(c) where t1.a=t2.a;
+explain select * from t1 where a=0 or a=2;
+explain select * from t1 force index (a) where a=0 or a=2;
+drop table t1,t2;

sql/lex.h

@@ -151,6 +151,7 @@ static SYMBOL symbols[] = {
   { "FLOAT8",		SYM(DOUBLE_SYM),0,0},
   { "FLUSH",		SYM(FLUSH_SYM),0,0},
   { "FOREIGN",		SYM(FOREIGN),0,0},
+  { "FORCE",		SYM(FORCE_SYM),0,0},
   { "RAID_TYPE",	SYM(RAID_TYPE),0,0},
   { "RAID_CHUNKS",	SYM(RAID_CHUNKS),0,0},
   { "RAID_CHUNKSIZE",	SYM(RAID_CHUNKSIZE),0,0},

sql/mysql_priv.h

@@ -226,6 +226,10 @@ void debug_sync_point(const char* lock_name, uint lock_timeout);
 #define SHOW_LOG_STATUS_FREE "FREE"
 #define SHOW_LOG_STATUS_INUSE "IN USE"
 
+/* Options to add_table_to_list() */
+#define TL_OPTION_UPDATING	1
+#define TL_OPTION_FORCE_INDEX	2
+
 /* Some portable defines */
 
 #define portable_sizeof_char_ptr 8
@@ -509,7 +513,7 @@ bool add_field_to_list(char *field_name, enum enum_field_types type,
 void store_position_for_column(const char *name);
 bool add_to_list(SQL_LIST &list,Item *group,bool asc=0);
 TABLE_LIST *add_table_to_list(Table_ident *table,LEX_STRING *alias,
-			      bool updating,
+			      ulong table_option,
 			      thr_lock_type flags=TL_UNLOCK,
 			      List<String> *use_index=0,
 			      List<String> *ignore_index=0);

sql/opt_range.cc

@@ -605,12 +605,14 @@ int SQL_SELECT::test_quick_select(key_map keys_to_use, table_map prev_tables,
     records++;					/* purecov: inspected */
   scan_time=(double) records / TIME_FOR_COMPARE+1;
   read_time=(double) head->file->scan_time()+ scan_time + 1.0;
+  if (head->force_index)
+    scan_time= read_time= DBL_MAX;
   if (limit < records)
     read_time=(double) records+scan_time+1;	// Force to use index
   else if (read_time <= 2.0 && !force_quick_range)
     DBUG_RETURN(0);				/* No need for quick select */
 
-  DBUG_PRINT("info",("Time to scan table: %ld",(long) read_time));
+  DBUG_PRINT("info",("Time to scan table: %g", read_time));
 
   keys_to_use&=head->keys_in_use_for_query;
   if (keys_to_use)

sql/sql_base.cc

@@ -752,7 +752,7 @@ TABLE *reopen_name_locked_table(THD* thd, TABLE_LIST* table_list)
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;
   table->const_table=0;
-  table->outer_join=table->null_row=table->maybe_null=0;
+  table->outer_join= table->null_row= table->maybe_null= table->force_index= 0;
   table->status=STATUS_NO_RECORD;
   table->keys_in_use_for_query= table->keys_in_use;
   table->used_keys= table->keys_for_keyread;
@@ -910,7 +910,7 @@ TABLE *open_table(THD *thd,const char *db,const char *table_name,
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;
   table->const_table=0;
-  table->outer_join=table->null_row=table->maybe_null=0;
+  table->outer_join= table->null_row= table->maybe_null= table->force_index= 0;
   table->status=STATUS_NO_RECORD;
   table->keys_in_use_for_query= table->keys_in_use;
   table->used_keys= table->keys_for_keyread;
@@ -981,6 +981,7 @@ bool reopen_table(TABLE *table,bool locked)
   tmp.status=		table->status;
   tmp.keys_in_use_for_query= tmp.keys_in_use;
   tmp.used_keys= 	tmp.keys_for_keyread;
+  tmp.force_index=	tmp.force_index;
 
   /* Get state */
   tmp.key_length=	table->key_length;
@@ -1888,6 +1889,7 @@ bool setup_tables(TABLE_LIST *tables)
     table->maybe_null=test(table->outer_join=table_list->outer_join);
     table->tablenr=tablenr;
     table->map= (table_map) 1 << tablenr;
+    table->force_index= table_list->force_index;
     if (table_list->use_index)
     {
       key_map map= get_key_map_from_key_list(table,

sql/sql_lex.h

@@ -110,7 +110,7 @@ typedef struct st_select_lex
   char *db,*db1,*table1,*db2,*table2;		/* For outer join using .. */
   Item *where,*having;
   ha_rows select_limit,offset_limit;
-  ulong options;
+  ulong options, table_join_options;
   List<List_item>     expr_list;
   List<List_item>     when_list;
   SQL_LIST	      order_list,table_list,group_list;

sql/sql_parse.cc

@@ -498,7 +498,8 @@ check_connections(THD *thd)
       vio_in_addr(net->vio,&thd->remote.sin_addr);
       thd->host=ip_to_hostname(&thd->remote.sin_addr,&connect_errors);
       /* Cut very long hostnames to avoid possible overflows */
-      thd->host[min(strlen(thd->host), HOSTNAME_LENGTH)]= 0;
+      if (thd->host)
+	thd->host[min(strlen(thd->host), HOSTNAME_LENGTH)]= 0;
       if (connect_errors > max_connect_errors)
 	return(ER_HOST_IS_BLOCKED);
     }
@@ -3158,12 +3159,30 @@ bool add_to_list(SQL_LIST &list,Item *item,bool asc)
 }
 
 
+/*
+  Add a table to list of used tables
+
+  SYNOPSIS
+    add_table_to_list()
+    table		Table to add
+    alias		alias for table (or null if no alias)
+    table_options	A set of the following bits:
+			TL_OPTION_UPDATING	Table will be updated
+			TL_OPTION_FORCE_INDEX	Force usage of index
+    lock_type		How table should be locked
+    use_index		List of indexed used in USE INDEX
+    ignore_index	List of indexed used in IGNORE INDEX
+
+    RETURN
+      0		Error
+      #		Pointer to TABLE_LIST element added to the total table list
+*/
+
 TABLE_LIST *add_table_to_list(Table_ident *table, LEX_STRING *alias,
-			      bool updating,
-			      thr_lock_type flags,
+			      ulong table_options,
+			      thr_lock_type lock_type,
 			      List<String> *use_index,
-			      List<String> *ignore_index
-			      )
+			      List<String> *ignore_index)
 {
   register TABLE_LIST *ptr;
   THD	*thd=current_thd;
@@ -3211,8 +3230,9 @@ TABLE_LIST *add_table_to_list(Table_ident *table, LEX_STRING *alias,
   }
   ptr->real_name=table->table.str;
   ptr->real_name_length=table->table.length;
-  ptr->lock_type=flags;
-  ptr->updating=updating;
+  ptr->lock_type= lock_type;
+  ptr->updating=    test(table_options & TL_OPTION_UPDATING);
+  ptr->force_index= test(table_options & TL_OPTION_FORCE_INDEX);
   if (use_index)
     ptr->use_index=(List<String> *) thd->memdup((gptr) use_index,
 					       sizeof(*use_index));
@@ -3221,7 +3241,7 @@ TABLE_LIST *add_table_to_list(Table_ident *table, LEX_STRING *alias,
 						   sizeof(*ignore_index));
 
   /* check that used name is unique */
-  if (flags != TL_IGNORE)
+  if (lock_type != TL_IGNORE)
   {
     for (TABLE_LIST *tables=(TABLE_LIST*) thd->lex.select->table_list.first ;
 	 tables ;

sql/sql_select.cc

@@ -2057,7 +2057,8 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
 	  !(s->quick && best_key && s->quick->index == best_key->key &&
 	    best_max_key_part >= s->table->quick_key_parts[best_key->key]) &&
 	  !((s->table->file->table_flags() & HA_TABLE_SCAN_ON_INDEX) &&
-	    s->table->used_keys && best_key))
+	    s->table->used_keys && best_key) &&
+	  !(s->table->force_index && best_key))
       {						// Check full join
 	if (s->on_expr)
 	{

sql/sql_yacc.yy

-/* Copyright (C) 2000-2001 MySQL AB
+/* Copyright (C) 2000-2003 MySQL AB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -198,6 +198,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b,int *yystacksize);
 %token	FIRST_SYM
 %token	FIXED_SYM
 %token	FLOAT_NUM
+%token	FORCE_SYM
 %token	FOREIGN
 %token	FROM
 %token	FULL
@@ -735,7 +736,8 @@ create:
 	  lex->sql_command= SQLCOM_CREATE_TABLE;
 	  if (!add_table_to_list($5,
 				 ($2 & HA_LEX_CREATE_TMP_TABLE ?
-				   &tmp_table_alias : (LEX_STRING*) 0),1))
+				   &tmp_table_alias : (LEX_STRING*) 0),
+				 TL_OPTION_UPDATING))
 	    YYABORT;
 	  lex->create_list.empty();
 	  lex->key_list.empty();
@@ -751,7 +753,7 @@ create:
 	  {
 	    LEX *lex=Lex;
 	    lex->sql_command= SQLCOM_CREATE_INDEX;
-	    if (!add_table_to_list($6,NULL,1))
+	    if (!add_table_to_list($6, NULL, TL_OPTION_UPDATING))
 	      YYABORT;
 	    lex->create_list.empty();
 	    lex->key_list.empty();
@@ -1171,7 +1173,7 @@ alter:
 	  LEX *lex=Lex;
 	  lex->sql_command = SQLCOM_ALTER_TABLE;
 	  lex->name=0;
-	  if (!add_table_to_list($4, NULL,1))
+	  if (!add_table_to_list($4, NULL, TL_OPTION_UPDATING))
 	    YYABORT;
 	  lex->drop_primary=0;
 	  lex->create_list.empty();
@@ -1442,8 +1444,9 @@ table_to_table_list:
 
 table_to_table:
 	table_ident TO_SYM table_ident
-	{ if (!add_table_to_list($1,NULL,1,TL_IGNORE) ||
-	      !add_table_to_list($3,NULL,1,TL_IGNORE))
+	{
+	   if (!add_table_to_list($1, NULL, TL_OPTION_UPDATING, TL_IGNORE) ||
+	       !add_table_to_list($3, NULL, TL_OPTION_UPDATING, TL_IGNORE))
 	     YYABORT;
  	};
 
@@ -2127,11 +2130,13 @@ join_table:
 	{
 	  SELECT_LEX *sel=Select;
 	  sel->use_index_ptr=sel->ignore_index_ptr=0;
+	  sel->table_join_options= 0;
 	}
         table_ident opt_table_alias opt_key_definition
 	{
 	  SELECT_LEX *sel=Select;
-	  if (!($$=add_table_to_list($2,$3,0,TL_UNLOCK, sel->use_index_ptr,
+	  if (!($$=add_table_to_list($2, $3, sel->table_join_options,
+				     TL_UNLOCK, sel->use_index_ptr,
 	                             sel->ignore_index_ptr)))
 	    YYABORT;
 	}
@@ -2150,12 +2155,20 @@ opt_key_definition:
 	    sel->use_index= *$2;
 	    sel->use_index_ptr= &sel->use_index;
 	  }
+	| FORCE_SYM key_usage_list
+          {
+	    SELECT_LEX *sel=Select;
+	    sel->use_index= *$2;
+	    sel->use_index_ptr= &sel->use_index;
+	    sel->table_join_options|= TL_OPTION_FORCE_INDEX;
+	  }
 	| IGNORE_SYM key_usage_list
 	  {
 	    SELECT_LEX *sel=Select;
 	    sel->ignore_index= *$2;
 	    sel->ignore_index_ptr= &sel->ignore_index;
-	  };
+	  }
+	;
 
 key_usage_list:
 	key_or_index { Select->interval_list.empty(); } '(' key_usage_list2 ')'
@@ -2443,7 +2456,7 @@ drop:
 	     lex->drop_list.empty();
 	     lex->drop_list.push_back(new Alter_drop(Alter_drop::KEY,
 						     $3.str));
-	     if (!add_table_to_list($5,NULL, 1))
+	     if (!add_table_to_list($5, NULL, TL_OPTION_UPDATING))
 	      YYABORT;
 	  }
 	| DROP DATABASE if_exists ident
@@ -2467,7 +2480,7 @@ table_list:
 
 table_name:
 	table_ident
-	{ if (!add_table_to_list($1,NULL,1)) YYABORT; };
+	{ if (!add_table_to_list($1,NULL,TL_OPTION_UPDATING)) YYABORT; };
 
 if_exists:
 	/* empty */ { $$= 0; }
@@ -2678,7 +2691,8 @@ delete:
 single_multi:
  	FROM table_ident
 	{
-	  if (!add_table_to_list($2, NULL, 1, Lex->lock_option))
+	  if (!add_table_to_list($2, NULL, TL_OPTION_UPDATING,
+				 Lex->lock_option))
 	    YYABORT;
 	}
 	where_clause opt_order_clause
@@ -2699,13 +2713,14 @@ table_wild_list:
 table_wild_one:
 	 ident opt_wild
 	 {
-	   if (!add_table_to_list(new Table_ident($1), NULL, 1,
-				  Lex->lock_option))
+	   if (!add_table_to_list(new Table_ident($1), NULL,
+				  TL_OPTION_UPDATING, Lex->lock_option))
 	     YYABORT;
          }
 	 | ident '.' ident opt_wild
 	   {
-	     if (!add_table_to_list(new Table_ident($1,$3,0), NULL, 1,
+	     if (!add_table_to_list(new Table_ident($1,$3,0), NULL,
+				    TL_OPTION_UPDATING,
 				    Lex->lock_option))
 	      YYABORT;
 	   }
@@ -2774,7 +2789,7 @@ show_param:
 	    Lex->sql_command= SQLCOM_SHOW_FIELDS;
 	    if ($5)
 	      $4->change_db($5);
-	    if (!add_table_to_list($4,NULL,0))
+	    if (!add_table_to_list($4, NULL, 0))
 	      YYABORT;
 	  }
         | NEW_SYM MASTER_SYM FOR_SYM SLAVE WITH MASTER_LOG_FILE_SYM EQ 
@@ -2807,7 +2822,7 @@ show_param:
 	    Lex->sql_command= SQLCOM_SHOW_KEYS;
 	    if ($4)
 	      $3->change_db($4);
-	    if (!add_table_to_list($3,NULL,0))
+	    if (!add_table_to_list($3, NULL, 0))
 	      YYABORT;
 	  }
 	| STATUS_SYM wild
@@ -2834,7 +2849,7 @@ show_param:
         | CREATE TABLE_SYM table_ident
           {
 	    Lex->sql_command = SQLCOM_SHOW_CREATE;
-	    if(!add_table_to_list($3, NULL,0))
+	    if(!add_table_to_list($3, NULL, 0))
 	      YYABORT;
 	  }
         | MASTER_SYM STATUS_SYM
@@ -2879,7 +2894,7 @@ describe:
 	  lex->wild=0;
 	  lex->verbose=0;
 	  lex->sql_command=SQLCOM_SHOW_FIELDS;
-	  if (!add_table_to_list($2, NULL,0))
+	  if (!add_table_to_list($2, NULL, 0))
 	    YYABORT;
 	}
 	opt_describe_column {}
@@ -2999,14 +3014,14 @@ load:	LOAD DATA_SYM load_data_lock opt_local INFILE TEXT_STRING
 	opt_duplicate INTO TABLE_SYM table_ident opt_field_term opt_line_term
 	opt_ignore_lines opt_field_spec
 	{
-	  if (!add_table_to_list($11,NULL,1))
+	  if (!add_table_to_list($11, NULL, TL_OPTION_UPDATING))
 	    YYABORT;
 	}
         |
 	LOAD TABLE_SYM table_ident FROM MASTER_SYM
         {
 	  Lex->sql_command = SQLCOM_LOAD_MASTER_TABLE;
-	  if (!add_table_to_list($3,NULL,1))
+	  if (!add_table_to_list($3, NULL, TL_OPTION_UPDATING))
 	    YYABORT;
 
         }

sql/table.h

@@ -91,6 +91,7 @@ struct st_table {
   my_bool copy_blobs;			/* copy_blobs when storing */
   my_bool null_row;			/* All columns are null */
   my_bool maybe_null,outer_join;	/* Used with OUTER JOIN */
+  my_bool force_index;
   my_bool distinct,const_table,no_rows;
   my_bool key_read, bulk_insert;
   my_bool crypted;
@@ -157,6 +158,7 @@ typedef struct st_table_list
   bool		straight;		/* optimize with prev table */
   bool          updating;               /* for replicate-do/ignore table */
   bool		do_redirect;		/* To get the struct in UNION's */
+  bool		force_index;		/* Prefer index over table scan */
 } TABLE_LIST;