bk commit into 5.0 tree (evgen:1.1989)

[eugene]

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5.0 repository of evgen. When evgen does a push these changes will
be propagated to the main repository and, within 24 hours after the
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ChangeSet
  1.1989 05/11/22 17:46:01 evgen@stripped +1 -0
  Merge epotemkin@stripped:/home/bk/mysql-5.0
  into moonbone.local:/work/13293-bug-5.0-mysql

  sql/opt_range.cc
    1.199 05/11/22 17:46:00 evgen@stripped +0 -0
    Auto merged

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	evgen
# Host:	moonbone.local
# Root:	/work/13293-bug-5.0-mysql/RESYNC

--- 1.198/sql/opt_range.cc	2005-11-20 21:47:00 +03:00
+++ 1.199/sql/opt_range.cc	2005-11-22 17:46:00 +03:00
@@ -6923,9 +6923,9 @@
     SA5. The select list in DISTINCT queries should not contain expressions.
     GA1. If Q has a GROUP BY clause, then GA is a prefix of I. That is, if
          G_i = A_j => i = j.
-    GA2. If Q has a DISTINCT clause, then there is a permutation of SA that
-         forms a prefix of I. This permutation is used as the GROUP clause
-         when the DISTINCT query is converted to a GROUP query.
+    GA2. If Q has a DISTINCT clause, then there is a permutation of SA.
+         This permutation is used as the GROUP clause when the DISTINCT
+         query is converted to a GROUP query.
     GA3. The attributes in GA may participate in arbitrary predicates, divided
          into two groups:
          - RNG(G_1,...,G_q ; where q <= k) is a range condition over the
@@ -7215,6 +7215,13 @@
         cur_used_key_parts.set_bit(key_part_nr);
         ++cur_group_key_parts;
       }
+      /*
+        For loose index scan being applicable for distinct all fields
+        should be covered by index and all parts of index should be used.
+      */
+      if (cur_group_key_parts != join->fields_list.elements ||
+          cur_group_key_parts != cur_index_info->key_parts)
+        goto next_index;
     }
     else
       DBUG_ASSERT(FALSE);