MySQL 5.1 Replication Delays


I noticed replication delays in MySQL 5.1. Data synchronizing is takes long on MySQL 5.1 slaves while MySQL 4.1 and MySQL 5.0 slaves working quite brilliant.

We have MySQL 4.1 acting as Master database while MySQL 4.1, MySQL 5.0 and MySQL 5.1 acting as slaves.

Can someone please let me know what are the SQL changes between MySQL 5.0 and MySQL 5.1. Because i noticed SQL queries are working as fast in MySQL 5.1 compare to MySQL 5.0. I analyzed this from slow queries log.

We have lot of queries with GROUP BY, ORDER BY and LIMIT clauses together. and LIMIT clauses with 4000,10 or 2000,10 etc. Also we have lot of SELECTs with JOINs on multiple tables.

Please let me know major SQL changes between MySQL 5.0 and MySQL 5.1.


You should have used mk-upgrade first ) The major changes are listed in the change logs in the manual – start there.

Sounds like you need to fix a lot of bad queries.


I am in the process of upgrading MySQL 4.1 slaves to MySQL 5.1. Some of the mysql queries are not performing well on MySQL 5.1. I need to get differences on both of the versions. I did following:

/usr/bin/mk-upgrade h= h= u=username p=passowrd –
'SELECT count(*) from table1;

In order to get the difference of query. u=username having SELECT
rights on both of database servers i.e. MySQL 4.1 and MySQL 5.1. But i got the following error.

DBI connect(’;host=;mysql_read_default_group=client’,’’, …)
failed: Access denied for user ‘root’@‘’ (using password: YES)
/usr/bin/mk-upgrade line 261

where is the ip address from where i running mk-upgrade

DBD::mysql::VERSION: 4.010
CentOS 4.7

Please let me know how to use mk-upgrade script i have quite few
queries and slow.log which i need to analyze on MySQL 4.1 and MySQL 5.1 servers on different physical machines. I am trying to connect both of MySQL remotely from where i installed mk-upgrade script.

Let me know what command should i use ? and what’s wrong with my
command i provided in this post.

Thank you.

I see that this topic is active in the Maatkit mailing list, so we should continue discussing it there.