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


BitKeeper/etc/ignore:
  Added configure.lineno innobase/configure.lineno innobase/stamp-h1 myisam/rt_test.MYD myisam/rt_test.MYI stamp-h1 to the ignore list
include/my_base.h:
  support for HA_READ_PREFIX_LAST_OR_PREV
myisam/mi_search.c:
  full support of HA_READ_PREFIX_LAST_OR_PREV in MyISAM
myisam/mi_static.c:
  full support of HA_READ_PREFIX_LAST_OR_PREV in MyISAM
sql/opt_range.cc:
  support for HA_READ_PREFIX_LAST_OR_PREV
  protected by #if NOT_IMPLEMENTED_YET, not all table handlers support it
sql/sql_handler.cc:
  support for HA_READ_PREFIX_LAST_OR_PREV

.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

@@ -57,6 +57,7 @@ enum ha_rkey_function {
   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,

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

@@ -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,