| Title | MySQL bug stops replicator from seeing some Bugzilla changes |
| Status | closed |
| Priority | critical |
| Assigned user | Nick Barnes |
| Organization | Ravenbrook |
| Description | The replicator may fail to notice some changes to Bugzilla bugs. In particular, the addition of a comment to a Bugzilla bug. This occurs with some versions of MySQL (e.g. 3.23.37) but not others (e.g. 3.22.32). |
| Analysis | This has the same underlying cause as job000345: some versions of MySQL fail to return some rows for some LEFT JOIN selects. To be specific, a LEFT JOIN with a table including a DATETIME column which is NOT NULL, WHERE not_null_datetime IS NULL, returns no rows. Here's a little example: Make a small database with these tables and this row: create table a (id int); create table b (id int, dt datetime not null, f int not null); insert into a values (1); Then each of these two queries correctly returns a single row. select a.id from a left join b using (id) where b.f is null; select a.id from a left join b using (id) where b.id is null; But this query returns the empty set: select a.id from a left join b using (id) where b.dt is null; We have such a query in the Bugzilla integration. We can work around this bug in MySQL by using WHERE some_other_field IS NULL. In particular, say "where bugs_activity.fieldid is null" instead of "where bugs_activity.bug_when is null". |
| How found | customer |
| Evidence | This is a detailed bug report from a user seeing this problem: <http://info.ravenbrook.com/mail/2001/07/12/14-05-53/0.txt>.This is mail from a user who found a different workaround: < http://info.ravenbrook.com/mail/2001/07/17/10-51-30/0.txt>. |
| Observed in | 1.1.1 |
| Introduced in | 0.5.0 |
| Test procedure | <http://www.ravenbrook.com/project/p4dti/master/test/test_p4dti.py> |
| Created by | Nick Barnes |
| Created on | 2001-07-16 12:49:01 |
| Last modified by | Gareth Rees |
| Last modified on | 2001-12-10 19:50:05 |
| History | 2001-07-16 NB Created. |
| Change | Effect | Date | User | Description |
|---|---|---|---|---|
| 14183 | closed | 2001-07-16 18:12:12 | Gareth Rees | Replicate new bugs in Bugzilla even in buggy MySQL versions like 3.23.37. |