Bug #7965 | Slave_IO_State Stuck at 'Checking Master Version' | ||
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Submitted: | 17 Jan 2005 17:52 | Modified: | 18 Jan 2005 13:13 |
Reporter: | Scott Nebor | Email Updates: | |
Status: | Closed | Impact on me: | |
Category: | MySQL Server: Replication | Severity: | S3 (Non-critical) |
Version: | 4.1.8 | OS: | Linux (Red Hat 9) |
Assigned to: | Guilhem Bichot | CPU Architecture: | Any |
[17 Jan 2005 17:52]
Scott Nebor
[17 Jan 2005 20:11]
Guilhem Bichot
Hi, This is specific of 3.23.x->4.1 replication where x is not a recent number (so, for example, 47, 49). The reason is that 4.1 issues a statement (SELECT @@GLOBAL.COLLATION_SERVER) which *hangs* on 3.23.x. It's a bug in 3.23.x. 3.23.58 does not have this bug. To work around, I will change 4.1.10 to not send this statement if it sees the master is 3.23. The reason things change after two hours is probably that some network timeout is 2 hours, causing the SELECT to finally fail, then slave I/O thread proceeds further.
[17 Jan 2005 20:20]
Guilhem Bichot
Exactly, the hang was fixed in 3.23.50; from the changelog: Fixed that @code{@@@@unknown_variable} doesn't hang server. Changing 4.1.10 to work around this problem.
[17 Jan 2005 21:21]
Scott Nebor
I noticed that the slave also issues a "SELECT @@GLOBAL.TIME_ZONE" in addition to the "SELECT @@GLOBAL.COLLATION_SERVER". I guess that this 4.1.10 should not issue this command either if the master version is below 3.23.50. FYI. I recompiled 4.1.8 so that it doesn't issue these two commands if the version is below 3.23.50 and this seemed to resolve the problem.
[17 Jan 2005 21:51]
Guilhem Bichot
Hi! Thanks for the verification, now we know it's really the cause. Yes, I also disabled the SELECT TIMEZONE the same way.
[18 Jan 2005 13:13]
Guilhem Bichot
Thank you for your bug report. This issue has been committed to our source repository of that product and will be incorporated into the next release. If necessary, you can access the source repository and build the latest available version, including the bugfix, yourself. More information about accessing the source trees is available at http://www.mysql.com/doc/en/Installing_source_tree.html Additional info: Fixed in 4.1.10 and 5.0.3 in ChangeSet@1.2130.1.2, 2005-01-17 21:26:14+01:00, guilhem@mysql.com Fix for BUG#7965 "Slave_IO_State Stuck at 'Checking Master Version'": Working around hang of master < 3.23.50 on SELECT @@unknown_var (to enable 3.23.49->4.1.10 replication)