Thanks for reply!
Yes, it is very slow too if I just execute the "select ..." part.
When I run
mysql> explain extended select a.*, b.assname, b.cname, b.cusip, b.own,
b.pname, b.sname from nber1999.pat1 as a inner join nber1999.compusta1
asb on a.assignee=b.assignee;
I got
+----+-------------+-------+------+---------------+------+---------+------+---------+-------------+
| id | select_type | table | type | possible_keys | key | key_len |
ref | rows | Extra |
+----+-------------+-------+------+---------------+------+---------+------+---------+-------------+
| 1 | SIMPLE | b | ALL | NULL | NULL | NULL |
NULL | 4906 | |
| 1 | SIMPLE | a | ALL | NULL | NULL | NULL |
NULL | 2089903 | Using where |
+----+-------------+-------+------+---------------+------+---------+------+---------+-------------+
2 rows in set, 1 warning (0.00 sec)
Best,
Jia
Dan Nelson wrote:
In the last episode (Aug 28), Jia Chen said:
One seemingly simple query that joins two tables takes a long time for me.
This is my library.
mysql> show table status from nber1999;
+-----------+--------+---------+------------+----------+----------------+-------------+------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-------------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length |
Data_length | Max_data_length | Index_length | Data_free | Auto_increment |
Create_time | Update_time | Check_time | Collation |
Checksum | Create_options | Comment |
+-----------+--------+---------+------------+----------+----------------+-------------+------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-------------------+----------+----------------+---------+
| compusta1 | MyISAM | 10 | Dynamic | 4906 | 77 |
379464 | 281474976710655 | 1024 | 0 | NULL |
2009-08-27 23:56:47 | 2009-08-27 23:56:47 | NULL | latin1_swedish_ci |
NULL | | |
| pat1 | MyISAM | 10 | Dynamic | 2089903 | 96 |
201936072 | 281474976710655 | 1024 | 0 | NULL |
2009-08-27 23:55:48 | 2009-08-27 23:55:56 | NULL | latin1_swedish_ci |
NULL | | |
+-----------+--------+---------+------------+----------+----------------+-------------+------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-------------------+----------+----------------+---------+
5 rows in set (0.00 sec)
And the relevant rows in my slow query log file is:
# Time: 090828 10:36:17
# u...@host: root[root] @ localhost []
# Query_time: 478 Lock_time: 0 Rows_sent: 0 Rows_examined: 1251
use nber1999;
create table nber1999.pat select a.*, b.assname, b.cname, b.cusip,
b.own, b.pname, b.sname
from nber1999.pat1 as a inner join nber1999.compusta1 as b
on a.assignee=b.assignee;
If you run just the "select ..." part, is it slow also? Do you have an
index on pat1.assignee? What does an EXPLAIN on the select print?
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