MySQL Bugs: #20382: mysqldump --result-file should not create half-empty file on errors

Bug #20382	mysqldump --result-file should not create half-empty file on errors
Submitted:	11 Jun 2006 19:35	Modified:	24 Jul 2006 18:38
Reporter:	Christian Hammers (Silver Quality Contributor) (OCA)	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Documentation	Severity:	S3 (Non-critical)
Version:	all	OS:	Any (all)
Assigned to:	Paul DuBois	CPU Architecture:	Any

Description:
As reported as Debian bug #372313 by Robert Sander:

If "mysqldump --result-file" is asked to dump a non-existant table, the output file consists only 
of the typical mysqldump header with no data. It would be nicer if the result file (which possibly contains the last valid dump of the table) would not be touched at all before the existence of the table has been checked.

How to repeat:
mysqldump --result-file=x sometablename

Suggested fix:
First the check then the action :)

Thank you for a problem report. Verified just as described with 5.0.23-BK on Linux:

openxs@suse:~/dbs/5.0> bin/mysqldump -uroot test sometablename
-- MySQL dump 10.10
--
-- Host: localhost    Database: test
-- ------------------------------------------------------
-- Server version       5.0.23

/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0
*/;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
mysqldump: Couldn't find table: "sometablename"

I think, it is a bug/documentation request. This results is not clearly documented at http://dev.mysql.com/doc/refman/5.0/en/mysqldump.html.

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 products.

I am not really clear why this has been closed. The behaviour is exactly the same. The notes say that the documentation has been updated. However I have looked and I can find no such warning.

"The result file is created and its previous contents overwritten, even if an error occurs while generating the dump."

Note "even if..."