support for HA_READ_PREFIX_LAST_OR_PREV in headres

full support for HA_READ_PREFIX_LAST_OR_PREV in MyISAM
protected by #if NOT_IMPLEMENTED_YET in opt_range.cc as not all table handlers support it

.bzrignore

@@ -505,3 +505,11 @@ vio/test-sslserver
 vio/viotest-ssl
 sql_error.cc
 sql_prepare.cc
+autom4te.cache/*
+innobase/autom4te.cache/*
+configure.lineno
+innobase/configure.lineno
+innobase/stamp-h1
+myisam/rt_test.MYD
+myisam/rt_test.MYI
+stamp-h1

include/my_base.h

@@ -50,13 +50,14 @@
 	/* The following is parameter to ha_rkey() how to use key */
 
 enum ha_rkey_function {
-  HA_READ_KEY_EXACT,			/* Find first record else error */
-  HA_READ_KEY_OR_NEXT,			/* Record or next record */
-  HA_READ_KEY_OR_PREV,			/* Record or previous */
-  HA_READ_AFTER_KEY,			/* Find next rec. after key-record */
-  HA_READ_BEFORE_KEY,			/* Find next rec. before key-record */
-  HA_READ_PREFIX,			/* Key which as same prefix */
-  HA_READ_PREFIX_LAST,			/* Last key with the same prefix */
+  HA_READ_KEY_EXACT,              /* Find first record else error */
+  HA_READ_KEY_OR_NEXT,            /* Record or next record */
+  HA_READ_KEY_OR_PREV,            /* Record or previous */
+  HA_READ_AFTER_KEY,              /* Find next rec. after key-record */
+  HA_READ_BEFORE_KEY,             /* Find next rec. before key-record */
+  HA_READ_PREFIX,                 /* Key which as same prefix */
+  HA_READ_PREFIX_LAST,            /* Last key with the same prefix */
+  HA_READ_PREFIX_LAST_OR_PREV,    /* Last or prev key with the same prefix */
   HA_READ_MBR_CONTAIN,
   HA_READ_MBR_INTERSECT,
   HA_READ_MBR_WITHIN,
@@ -66,7 +67,7 @@ enum ha_rkey_function {
 
 	/* Key algorithm types */
 
-enum ha_key_alg {			
+enum ha_key_alg {
   HA_KEY_ALG_UNDEF=	0,		/* Not specified (old file) */
   HA_KEY_ALG_BTREE=	1,		/* B-tree, default one          */
   HA_KEY_ALG_RTREE=	2,		/* R-tree, for spatial searches */
@@ -202,7 +203,7 @@ enum ha_base_keytype {
 	/* Bits in flag to _status */
 
 #define HA_STATUS_POS		1		/* Return position */
-#define HA_STATUS_NO_LOCK 	2		/* Don't use external lock */
+#define HA_STATUS_NO_LOCK	2		/* Don't use external lock */
 #define HA_STATUS_TIME		4		/* Return update time */
 #define HA_STATUS_CONST		8		/* Return constants values */
 #define HA_STATUS_VARIABLE	16
@@ -233,7 +234,7 @@ enum ha_base_keytype {
 #define HA_ERR_WRONG_TABLE_DEF	 143
 #define HA_ERR_CRASHED_ON_REPAIR 144	/* Last (automatic?) repair failed */
 #define HA_ERR_CRASHED_ON_USAGE  145	/* Table must be repaired */
-#define HA_ERR_LOCK_WAIT_TIMEOUT 146    
+#define HA_ERR_LOCK_WAIT_TIMEOUT 146
 #define HA_ERR_LOCK_TABLE_FULL   147
 #define HA_ERR_READ_ONLY_TRANSACTION 148 /* Updates not allowed */
 #define HA_ERR_LOCK_DEADLOCK	 149
@@ -272,7 +273,7 @@ enum ha_base_keytype {
 #define READ_CHECK_USED 4
 #define KEY_READ_USED	8
 #define WRITE_CACHE_USED 16
-#define OPT_NO_ROWS 	32
+#define OPT_NO_ROWS	32
 
 	/* bits in update */
 #define HA_STATE_CHANGED	1	/* Database has changed */
@@ -302,7 +303,7 @@ enum data_file_type {
 #ifdef BIG_TABLES
 typedef my_off_t	ha_rows;
 #else
-typedef ulong		ha_rows;	
+typedef ulong		ha_rows;
 #endif
 
 #define HA_POS_ERROR	(~ (ha_rows) 0)

myisam/mi_search.c

@@ -132,7 +132,7 @@ int _mi_search(register MI_INFO *info, register MI_KEYDEF *keyinfo,
     if (_mi_get_prev_key(info,keyinfo, buff, info->lastkey, keypos,
                          &info->lastkey_length))
       goto err;
-    if ((nextflag & SEARCH_LAST) &&
+    if (!(nextflag & SEARCH_SMALLER) &&
         ha_key_cmp(keyinfo->seg, info->lastkey, key, key_len, SEARCH_FIND,
                     &not_used))
     {

myisam/mi_static.c

@@ -51,12 +51,12 @@ uint NEAR myisam_read_vec[]=
 {
   SEARCH_FIND, SEARCH_FIND | SEARCH_BIGGER, SEARCH_FIND | SEARCH_SMALLER,
   SEARCH_NO_FIND | SEARCH_BIGGER, SEARCH_NO_FIND | SEARCH_SMALLER,
-  SEARCH_FIND | SEARCH_PREFIX, SEARCH_LAST, 
+  SEARCH_FIND | SEARCH_PREFIX, SEARCH_LAST, SEARCH_LAST | SEARCH_SMALLER,
   MBR_CONTAIN, MBR_INTERSECT, MBR_WITHIN, MBR_DISJOINT, MBR_EQUAL
 };
 
 uint NEAR myisam_readnext_vec[]=
 {
   SEARCH_BIGGER, SEARCH_BIGGER, SEARCH_SMALLER, SEARCH_BIGGER, SEARCH_SMALLER,
-  SEARCH_BIGGER, SEARCH_SMALLER
+  SEARCH_BIGGER, SEARCH_SMALLER, SEARCH_SMALLER
 };

sql/opt_range.cc

@@ -2238,7 +2238,7 @@ check_quick_keys(PARAM *param,uint idx,SEL_ARG *key_tree,
     {
       tmp=param->table->file->
 	records_in_range((int) keynr,(byte*)(param->min_key + 1),
-	  min_key_length, (ha_rkey_function)(tmp_min_flag ^ GEOM_FLAG), 
+	  min_key_length, (ha_rkey_function)(tmp_min_flag ^ GEOM_FLAG),
           (byte *)NullS,0,HA_READ_KEY_EXACT);
     }
     else
@@ -2705,20 +2705,28 @@ int QUICK_SELECT_DESC::get_next()
     }
     else
     {
+      DBUG_ASSERT(range->flag & NEAR_MAX || range_reads_after_key(range));
+#if NOT_IMPLEMENTED_YET
+      result=file->index_read(record, (byte*) range->max_key,
+			      range->max_length,
+			      ((range->flag & NEAR_MAX) ?
+			       HA_READ_BEFORE_KEY : HA_READ_PREFIX_LAST_OR_PREV));
+#else
       /* Heikki changed Sept 11, 2002: since InnoDB does not store the cursor
 	 position if READ_KEY_EXACT is used to a primary key with all
 	 key columns specified, we must use below HA_READ_KEY_OR_NEXT,
 	 so that InnoDB stores the cursor position and is able to move
 	 the cursor one step backward after the search. */
 
-      DBUG_ASSERT(range->flag & NEAR_MAX || range_reads_after_key(range));
       /* Note: even if max_key is only a prefix, HA_READ_AFTER_KEY will
        * do the right thing - go past all keys which match the prefix */
+
       result=file->index_read(record, (byte*) range->max_key,
 			      range->max_length,
 			      ((range->flag & NEAR_MAX) ?
 			       HA_READ_KEY_OR_NEXT : HA_READ_AFTER_KEY));
       result = file->index_prev(record);
+#endif
     }
     if (result)
     {

sql/sql_handler.cc

@@ -88,7 +88,7 @@ int mysql_ha_close(THD *thd, TABLE_LIST *tables, bool dont_send_ok)
 }
 
 static enum enum_ha_read_modes rkey_to_rnext[]=
-    { RNEXT, RNEXT, RPREV, RNEXT, RPREV, RNEXT, RPREV };
+    { RNEXT, RNEXT, RPREV, RNEXT, RPREV, RNEXT, RPREV, RPREV };
 
 
 int mysql_ha_read(THD *thd, TABLE_LIST *tables,