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A common question I get about Percona XtraDB Cluster is if you can mix it with asynchronous replication, and the answer is yes! You can pick any node in your cluster and it can either be either a slave or a master just like any other regular MySQL standalone server (Just be sure to use log-slave-updates in both cases on the node in question!). Consider this architecture:
However, there are some caveats to be aware of. If you slave from a cluster node, there is no built in mechanism to fail that slave over automatically to another master node in your cluster. You cannot assume that the binary log positions are the same on all nodes in[Read more...]
The main benefit of using GTIDs is to have much easier failover than with file-based replication. We will see how to change the replication topology when using GTID-based replication. That will show where GTIDs shine and where improvements are expected.
This is the second post of a series of articles focused on MySQL 5.6 GTIDs. You can find part one here.
Our goal will be to go from setup #1 to setup #2 on the picture below, following various scenarios:
For these tests, all servers are running[Read more...]
Global Transactions Identifiers are one of the new features regarding replication in MySQL 5.6. They open up a lot of opportunities to make the life of DBAs much easier when having to maintain servers under a specific replication topology. However you should keep in mind some limitations of the current implementation. This post is the first one of a series of articles focused on the implications of enabling GTIDs on a production setup.
The manual describes very nicely how to switch to GTID-based replication, I won’t repeat[Read more...]
Global Transaction Identifiers (GTIDs) are one of the key replication enhancements in MySQL 5.6. GTIDs make it simple to track and compare replication across a master - slave topology. This enables:
- Much simpler recovery from failures of the master,
- Introduces great flexibility in the provisioning and on-going management of multi-tier or ring (circular) replication topologies.
A new on-demand MySQL 5.6 GTID webinar (http://www.mysql.com/news-and-events/web-seminars/mysql-replication-simplifying-scaling-and-ha-with-gtids/) delivered by the replication engineering team is now available, providing deep insight into the design and implementation of GTIDs, and how they enable users to simplify MySQL scaling and HA. The webinar covers:
- Concepts: What is[Read more...]
MySQL 5.6 seems to be ready for GA. I have no inside information about it, but from some clues collected in various places I feel that the release should not be far away. Thus, it's time for some serious testing, and for that purpose I have worked at updating MySQL Sandbox with some urgent features.
I have just released MySQL Sandbox 3.0.28, with more support for MySQL 5.6. Notably in this release, there is suppression of MySQL 5.6 annoying verbosity, additional suppression of more annoying warnings ( actually a bug) when using empty passwords[Read more...]
CREATE TABLE my_masters ( idx INT AUTO_INCREMENT, host CHAR(50) NOT NULL,[Read more...]
Not much to add really to the bug I’ve filed here: bug#67159.
Again this GTID stuff looks good, but seems to prevent changes in the configuration of performance_schema, which I think is not appropriate, especially as P_S now has lots of extra goodies and after 5.6 will surely have even more.
Not much to add really to the bug I’ve filed here: bug#67099.
I personally can think of some very nasty consequences of applying this on the slaves I manage, and the reason I’m posting the bug is that while I guess this is too late to fix in 5.6 as it’s effectively a new feature, I’m sure many sites may bump into this and be somewhat disappointed if they want to use the new GTID feature and have several slaves. Hence, if the fix/feature has to go into MySQL 5.7 then I hope it goes in sooner rather than later. We will see.
A colleague, Kris, commented recently on a recent find I made on 5.6.7-rc1 which while not the end of the world does seem to severely limit the use of the new GTID features, or if nothing else make it a pain to use.
Today I found another related issue, when trying to check the syntax of one of the MySQL commands. That’s now reported as bug#67073.
All of these are sort of edge cases but do make 5.6 look a little rough round the edges, when the rest of the product is actually really good and a great improvement from The MySQL 5.5 GA version that everyone uses. That’s really a shame.
I did report the Original problem as SR 3-6270525721 : MySQL 5.6.7-rc1, grants, replication and[Read more...]
On Wednesday May 16th, we ran a webinar to provide an overview of all of the new replication features and enhancements that are previewed in the MySQL 5.6 Development Release – including Global Transaction IDs, auto-failover[Read more...]
New versions of MySQL are always interesting to try out. Often they have features which I may have asked for myself so it’s satisfying to see them eventually appear on a system I use. Often other new features make life easier for the DBA. Finally we hope overall performance will improve and managing the server(s) will be come easier.
So I had a system which needs to make heavy writes, and performance was a problem, even when writing to SSDs. Checkpointing seemed to be the big issue and the ib_logfile size in MySQL 5.5 is limited to 4 GB. That seems a lot, but once MySQL starts to fill these files (and this happens at ~70% of the total I believe), checkpointing kicks in heavily, and slows things down. So the main reason for trying out MySQL 5.6 was to see how things performed with larger ib_logfiles. (Yes, MariaDB 5.5 can do this too.)
Things improved a lot for my[Read more...]
With all of the new news coming out right now, it can be easy to miss or overlook some of the new features.
While there’s been a lot of talk about MySQL 5.6 Replication, I specifically wanted to mention the new ‘mysqlfailover’ and ‘mysqlrpladmin’ utilities.
These are two new MySQL replication utilities (results of the new Global Transaction Identifiers (GTIDs) in MySQL 5.6).
Let me quote the MySQL 5.6 Replication article for both of these utilities:
“Provides continuous monitoring of the replication topology, enabling failover to a slave in the event of an outage on the master.
The default behavior is to[Read more...]
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