bzr commit into mysql-5.1 branch (v.narayanan:2680) Bug#38338

[Narayanan V]

#At
file:///home/vn/work/mysql/workspaces-bazaar/shared_repository_directory/mysql-5.1-bug38338/

 2680 Narayanan V	2008-08-17
      Bug#38338
      
      Fix the write_record function to record auto increment
      values in a consistent way.
modified:
  sql/sql_insert.cc

per-file messages:
  sql/sql_insert.cc
    The algorithm for the write_record function
    in sql_insert.cc is (more emphasis given to
    the parts that deal with the autogenerated values)
    
    1) If a write fails
    
       1.1) save the autogenerated value to avoid 
            thd->insert_id_for_cur_row to become 0.
    
       1.2) <logic to handle INSERT ON DUPLICATE KEY
             UPDATE and REPLACE>
    
    2) record the first successful insert id.
    
    explanation of the failure
    --------------------------
    
    As long as 1.1) was executed 2) worked fine.
    
    1.1) was always executed when REPLACE worked 
         with the last row update optimization, but
         in cases where 1.1) was not executed 2)
         would fail and would result in the autogenerated
         value not being saved.
    
    solution
    --------
    
    repeat a check for thd->insert_id_for_cur_row 
    being zero similar to 1.1) before 2) and ensure
    that the correct value is saved.
=== modified file 'sql/sql_insert.cc'
--- a/sql/sql_insert.cc	2008-07-11 18:51:10 +0000
+++ b/sql/sql_insert.cc	2008-08-17 17:12:39 +0000
@@ -1545,6 +1545,17 @@ int write_record(THD *thd, TABLE *table,
         }
       }
     }
+    
+    /*
+        If more than one iteration of the above while loop is done, from the second 
+        one the row being inserted will have an explicit value in the autoinc field, 
+        which was set at the first call of handler::update_auto_increment(). This 
+        value is saved to avoid thd->insert_id_for_cur_row becoming 0. Use this saved
+        autoinc value.
+     */
+    if (table->file->insert_id_for_cur_row <= 0)
+      table->file->insert_id_for_cur_row= insert_id_for_cur_row;
+      
    
thd->record_first_successful_insert_id_in_cur_stmt(table->file->insert_id_for_cur_row);
     /*
       Restore column maps if they where replaced during an duplicate key