| Bug #1389 | ALTER TABLE allows changing TYPE of MERGE table | ||
|---|---|---|---|
| Submitted: | 24 Sep 2003 6:52 | Modified: | 12 Dec 2003 14:04 |
| Reporter: | Jeremy Cole (Basic Quality Contributor) (OCA) | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Documentation | Severity: | S3 (Non-critical) |
| Version: | All | OS: | Any (All) |
| Assigned to: | Paul DuBois | CPU Architecture: | Any |
[16 Oct 2003 8:53]
Victor Vagin
Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.mysql.com/documentation/ and the instructions on how to report a bug at http://bugs.mysql.com/how-to-report.php it may be useful to change type. warning will not help you, because you will see it after converting.
[16 Oct 2003 9:13]
Jeremy Cole
If this is an expected behaviour and there is no intention to change it, then at very least it should be documented properly. I will however disagree that it is a useful feature, as there are many other, more proper ways to achieve the same goal. I would still prefer that it returned an error (which could suggest a proper way).
[12 Dec 2003 8:57]
Victor Vagin
[20:44] <vva> monty: btw, could you settle a dispute between
me and Jeremy Cole about Bug #1389 "ALTER TABLE allows changing
TYPE of MERGE table " (http://bugs.mysql.com/bug.php?id=1389)
[20:44] <vva> shall I fix it?
[20:55] <monty> checking
[20:57] <monty> I agree with you that it works like intended
[20:58] <monty> I don't see anything wrong with the current one;
The only differnce compared to a normal ALTER TABLE is that
you still have the original data left in the mapped tables
[20:59] <monty> send an email to docs-request to document this
properly and change bug report to docs-request
[12 Dec 2003 14:04]
Paul DuBois
Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly, and will be included in the next release of the relevant product(s).
Description: ALTER TABLE allows you to change the TYPE of a MERGE table to another type without any error or warning. It actually copies the rows from the underlying MyISAM tables to the new table. How to repeat: mysql> create table t1 (i int); Query OK, 0 rows affected (0.00 sec) mysql> create table t2 (i int); Query OK, 0 rows affected (0.00 sec) mysql> create table total (i int) type=merge union=(t1, t2); Query OK, 0 rows affected (0.00 sec) mysql> insert into t1 (i) values (1); Query OK, 1 row affected (0.00 sec) mysql> insert into t2 (i) values (2); Query OK, 1 row affected (0.00 sec) mysql> show table status like 'total' \G *************************** 1. row *************************** Name: total Type: MRG_MyISAM Row_format: Fixed Rows: 2 Avg_row_length: 5 Data_length: 10 Max_data_length: NULL Index_length: 0 Data_free: 0 Auto_increment: NULL Create_time: NULL Update_time: NULL Check_time: NULL Charset: latin1_swedish_ci Checksum: NULL Create_options: Comment: 1 row in set (0.01 sec) mysql> alter table total type=myisam; Query OK, 2 rows affected (0.01 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> show table status like 'total' \G *************************** 1. row *************************** Name: total Type: MyISAM Row_format: Fixed Rows: 2 Avg_row_length: 5 Data_length: 10 Max_data_length: 21474836479 Index_length: 1024 Data_free: 0 Auto_increment: NULL Create_time: 2003-09-24 09:48:49 Update_time: 2003-09-24 09:48:49 Check_time: NULL Charset: latin1_swedish_ci Checksum: NULL Create_options: Comment: 1 row in set (0.00 sec) Suggested fix: I would recommend it to be an error to change the TYPE of a MERGE table. Doing so could cause a lot of trouble if it was a merge of many large tables. At very least it should generate a warning on 4.1.