bk commit into 5.0 tree (kostja:1.2237) BUG#14897

[konstantin]

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ChangeSet@stripped, 2006-07-20 03:02:42+04:00, kostja@stripped +1 -0
  A fix for Bug#14897 "ResultSet.getString("table.column") sometimes 
  doesn't find the column"
  
  When a user was using 4.1 tables with VARCHAR column and 5.0 server
  and a query that used a temporary table to resolve itself, the
  table metadata for the varchar column sent to client was incorrect:
  MYSQL_FIELD::table member was empty.
  
  The bug was caused by implicit "upgrade" from old VARCHAR to new
  VARCHAR hard-coded in Field::new_field, which did not preserve
  the information about the original table. Thus, the field metadata
  of the "upgraded" field pointed to an auxiliary temporary table
  created for query execution.
  
  The fix is to copy the pointer to the original table to the new field.
  
  QQQ: Why if 'convert_blob_length' is TRUE create_tmp_field_from_field
  does not preserve the original table? Is this a similar problem?
  
  No test case as thisi s an upgrade-downgrade issue, 4.1 table is
  needed to reproduce. 

  sql/field.cc@stripped, 2006-07-20 03:02:38+04:00, kostja@stripped +13 -8
    Preserve the original table name when converting fields from
    old VARCHAR to new VARCHAR.

# 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:	kostja
# Host:	bodhi.local
# Root:	/opt/local/work/mysql-5.0-14897

--- 1.314/sql/field.cc	2006-07-20 03:02:51 +04:00
+++ 1.315/sql/field.cc	2006-07-20 03:02:51 +04:00
@@ -6234,15 +6234,20 @@ Field *Field_string::new_field(MEM_ROOT 
   Field *new_field;
 
   if (type() != MYSQL_TYPE_VAR_STRING || keep_type)
-    return Field::new_field(root, new_table, keep_type);
+    new_field= Field::new_field(root, new_table, keep_type);
+  else
+  {
 
-  /*
-    Old VARCHAR field which should be modified to a VARCHAR on copy
-    This is done to ensure that ALTER TABLE will convert old VARCHAR fields
-    to now VARCHAR fields.
-  */
-  return new Field_varstring(field_length, maybe_null(),
-                             field_name, new_table, charset());
+    /*
+      Old VARCHAR field which should be modified to a VARCHAR on copy
+      This is done to ensure that ALTER TABLE will convert old VARCHAR fields
+      to now VARCHAR fields.
+    */
+    new_field= new Field_varstring(field_length, maybe_null(),
+                                   field_name, new_table, charset());
+    new_field->orig_table= orig_table;
+  }
+  return new_field;
 }
 
 /****************************************************************************