Fix for MDEV-3948, and backport of the following collection of fixes and backports

from MariaDB 10.0.
  
The bug in mdev-3948 was an instance of the problem fixed by Sergey's patch
in 10.0 - namely that the range optimizer could change table->[read | write]_set,
and not restore it.
  
revno: 3471
committer: Sergey Petrunya <psergey@askmonty.org>
branch nick: 10.0-serg-fix-imerge
timestamp: Sat 2012-11-03 12:24:36 +0400
message:
  # MDEV-3817: Wrong result with index_merge+index_merge_intersection, InnoDB table, join, AND and OR conditions
  Reconcile the fixes from:
  #
  # guilhem.bichot@oracle.com-20110805143029-ywrzuz15uzgontr0
  # Fix for BUG#12698916 - "JOIN QUERY GIVES WRONG RESULT AT 2ND EXEC. OR
  # AFTER FLUSH TABLES [-INT VS NULL]"
  #
  # guilhem.bichot@oracle.com-20111209150650-tzx3ldzxe1yfwji6
  # Fix for BUG#12912171 - ASSERTION FAILED: QUICK->HEAD->READ_SET == SAVE_READ_SET
  # and
  #
  and related fixes from: BUG#1006164, MDEV-376:
  
  Now, ROR-merged QUICK_RANGE_SELECT objects make no assumptions about the values
  of table->read_set and table->write_set.
  Each QUICK_ROR_SELECT has (and had before) its own column bitmap, but now, all 
  QUICK_ROR_SELECT's functions that care: reset(), init_ror_merged_scan(), and 
  get_next()  will set table->read_set when invoked and restore it back to what 
  it was before the call before they return.

  This allows to avoid the mess when somebody else modifies table->read_set for 
  some reason.

1 files changed, 10 insertions, 4 deletions

diff --git a/sql/sql_update.cc b/sql/sql_update.cc
index 5836f7bf5dc..f59dfb3bc93 100644
--- a/sql/sql_update.cc
+++ b/sql/sql_update.cc
@@ -480,12 +480,15 @@ int mysql_update(THD *thd,
       We can't update table directly;  We must first search after all
       matching rows before updating the table!
     */
+
+    // Verify that table->restore_column_maps_after_mark_index() will work
+    DBUG_ASSERT(table->read_set == &table->def_read_set);
+    DBUG_ASSERT(table->write_set == &table->def_write_set);
+
     if (used_index < MAX_KEY && old_covering_keys.is_set(used_index))
       table->add_read_columns_used_by_index(used_index);
     else
-    {
       table->use_all_columns();
-    }
 
     /* note: We avoid sorting if we sort on the used index */
     if (order && (need_sort || used_key_is_modified))
@@ -619,8 +622,11 @@ int mysql_update(THD *thd,
       if (error >= 0)
 	goto err;
     }
-    if (table->key_read)
-      table->restore_column_maps_after_mark_index();
+    /*
+      This restore bitmaps, works for add_read_columns_used_by_index() and
+      use_all_columns():
+    */
+    table->restore_column_maps_after_mark_index();
   }
 
   if (ignore)