Bug #42321 --change_user with default args works different in embedded and standalone mode
Submitted: 24 Jan 2009 14:05 Modified: 9 Jan 2015 16:01
Reporter: Gleb Shchepa Email Updates:
Status: Can't repeat Impact on me:
None 
Category:Tools: MTR / mysql-test-run Severity:S3 (Non-critical)
Version:5.0, 5.1, 6.0 bzr OS:Any
Assigned to: Bjørn Munch CPU Architecture:Any
Tags: change_user, embedded, mysqltest, regression
Triage: Needs Triage: D3 (Medium)

[24 Jan 2009 14:05] Gleb Shchepa
Description:
The mysqltest client executes the "change_user" command without database name parameter differently under standalone and embedded server mode:

a) for standalone server mode it uses _current_ database as default database,
b) for embedded server it uses _no_ database as default database.

How to repeat:
Standard test file:

--disable_warnings
DROP TABLE IF EXISTS t1;
--enable_warnings
CREATE TABLE t1 (i INT);
--change_user
SELECT * FROM t1;
DROP TABLE t1;

Standalone server mode: no errors.
Embedded server mode:

mysqltest: At line 6: query 'SELECT * FROM t1' failed: 1046: No database selected

Suggested fix:
For a standalone mode a client program calls CLI_MYSQL_REAL_CONNECT() that set MYSQL::db field to opening database name. Then mysqltest uses that field value as default database name for --change_user command etc. However, a client doesn't call that function in embedded mode, and its MYSQL::db field is always set to NULL.

Probably it may be a robust solution to move an assignment of the current database name to MYSQL::db field from the CLI_MYSQL_REAL_CONNECT function to all kinds of mysql_real_connect function.
[25 Jan 2009 17:14] Sveta Smirnova
Thank you for the report.

Verified as described. With version 4.1 bug is not repeatable.