C:\build\5.1\bin>mysql -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.1.16-beta-nt Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> create database db5;
Query OK, 1 row affected (0.03 sec)

mysql> use db5
Database changed
mysql> source c:/a/mysqlbug.sql
Query OK, 0 rows affected (0.23 sec)
<cut>

mysql> EXPLAIN SELECT * FROM transaction WHERE first_name='Andy' OR last_name='Jake'\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: transaction
         type: index_merge
possible_keys: first_index,last_index
          key: first_index,last_index
      key_len: 43,53
          ref: NULL
         rows: 6
        Extra: Using union(first_index,last_index); Using where
1 row in set (0.00 sec)

mysql> SELECT * FROM transaction WHERE first_name='Jake'
    -> OR last_name='Chung';
ERROR 2013 (HY000): Lost connection to MySQL server during query
mysql>

CALL STACK

>	mysqld-nt.exe!ha_partition::open(const char * name=0x01bccbd0, int mode=39, unsigned int test_if_locked=2)  Line 2232 + 0x27	C++
 	mysqld-nt.exe!handler::ha_open(st_table * table_arg=0x01bcb1f0, const char * name=0x01bccbd0, int mode=39, int test_if_locked=2)  Line 1527 + 0x1c	C++
 	mysqld-nt.exe!handler::clone(st_mem_root * mem_root=0x01bb81dc)  Line 1465 + 0x21	C++
 	mysqld-nt.exe!QUICK_RANGE_SELECT::init_ror_merged_scan(int reuse_handler=0)  Line 1167 + 0xe	C++
 	mysqld-nt.exe!QUICK_ROR_UNION_SELECT::reset()  Line 1401 + 0x7	C++
 	mysqld-nt.exe!join_init_read_record(st_join_table * tab=0x073d78b0)  Line 11210 + 0x17	C++
 	mysqld-nt.exe!sub_select(JOIN * join=0x073d1440, st_join_table * join_tab=0x073d78b0, int end_of_records=0)  Line 10567	C++
 	mysqld-nt.exe!do_select(JOIN * join=0x00000000, List<Item> * fields=0x01bb8588, st_table * table=0x01bcb71c, Procedure * procedure=0x00000000)  Line 10330 + 0x9	C++
 	mysqld-nt.exe!JOIN::exec()  Line 1931	C++
 	mysqld-nt.exe!mysql_select(THD * thd=0x01bb81c0, Item * * * rref_pointer_array=0x01bb8618, st_table_list * tables=0x073d0d90, unsigned int wild_num=1, List<Item> & fields={...}, Item * conds=0x073d1348, unsigned int og_num=0, st_order * order=0x00000000, st_order * group=0x00000000, Item * having=0x00000000, st_order * proc_param=0x00000000, unsigned __int64 select_options=2147764736, select_result * result=0x073d1430, st_select_lex_unit * unit=0x01bb8270, st_select_lex * select_lex=0x01bb84f0)  Line 2097	C++
 	mysqld-nt.exe!handle_select(THD * thd=0x01bb81c0, st_lex * lex=0x01bb8200, select_result * result=0x073d1430, unsigned long setup_tables_done_option=0)  Line 255 + 0x79	C++
 	mysqld-nt.exe!execute_sqlcom_select(THD * thd=0x00070023, st_table_list * all_tables=0x00000000)  Line 5344 + 0xa	C++
 	mysqld-nt.exe!mysql_execute_command(THD * thd=0x61736e61)  Line 3720	C++
 	mysqld-nt.exe!mysql_parse(THD * thd=0x01bb81c0, char * inBuf=0x073d0c40, unsigned int length=70)  Line 6165	C++
 	mysqld-nt.exe!dispatch_command(enum_server_command command=COM_QUERY, THD * thd=0x01bb81c0, char * packet=0x073c8c11, unsigned int packet_length=71)  Line 1861	C++
 	mysqld-nt.exe!do_command(THD * thd=0x01bb81c0)  Line 1628 + 0xd	C++
 	mysqld-nt.exe!handle_one_connection(void * arg=0x01bb81c0)  Line 1234 + 0xa	C++
 	mysqld-nt.exe!_pthread_start()  + 0x3b	C
 	mswsock.dll!71a15ccc() 	
 	mysqld-nt.exe!_threadstart(void * ptd=0x01bb1728)  Line 196 + 0x6	C
 	kernel32.dll!7c80b683() 	
 	mswsock.dll!71a15ccc()