Note: My views are just that: mine.
1. Real time Query Monitoring
MySQL 5.0 GA provides only 3 ways to look at queries that are executed on a server in some way or another. Slow Query Log, General Query Log and Binary Log. All require a server reboot to activate and de-activate. In a production system, it’s sometimes critical to be able to know “what is going on”, and you simply can’t reboot the server twice (once to turn on, once to turn off). 5.1 goes some way with Log Tables to being able to turn on General and Slow Logs into tables. Question is, as Kevin Burton listed in his points, when is 5.1 going to be out.
Real time query monitoring also needs to have a granularity of operation better then “server”. There needs to be a capacity to assign this on per connection basis. A server is being hammered, certain status variables are increasing greatly, I need to know now what queries are causing this. MySQL provides no means of doing this. MySQL Proxy is a great new idea/project people will start hearing more about, and it goes a long way to helping, but it’s not dynamic in that I can simply turn on logging on a production system without impact to the MySQL server or connections.
Real time query monitoring granularity of time, also need to be in better units, it’s very difficult to find slow running queries > 100ms when the present granularity is seconds. MySQL Proxy as mentioned, and also Connector/J provide this, (BTW Connector/J has excellent features in it’s many connection options if you develop with Java but it’s yet another output to look at, and when your application server and database servers are on different machine architectures it’s a lot of work to sync).
I am also behind SHOW PROFILE. I’d like to see it being able to be attached to existing connections, and applied to queries, and then output discarded for a time base condition (say < 100ms). Granted the act of observation slows things done, it the ability to be able to observe, see and use the information that’s around in bits that would be a start.
2. Consistent Release Cycles
As Stewart pointed out, it’s ridiculous to have 2 years for release of a product. A consistent cycle is needed. 5.0 Change Notes shows first release to GA 22 months. 5.1 Change Notes still not GA is at 19 months.
We talk now about getting new features, 5.1 is frozen, 5.2 seems lost now in any discussions. 6.0 has a few key features but I’m sure significant new features will be limited to ensure the exposure of Falcon. So, a key new feature maybe in 6.1+
Scope creep, lack of clear planning, test coverage, and user community contribution I feel are all factors. I know that user community testing and contribution is continuing to increase and I applaud the valuable contribution of the community. I wish I could do more myself.
3. Information Schema Extensions
I’ve heard of a Pluggable API for I_S tables in 5.1 Could somebody really confirm? I’ve seen Google doing File System Storage Engines (e.g. for /proc info). I really, really, really wish things like 5.1 processlist and status/variables tables were backported to 5.0 to start with.
In addition, now that I have started, there is need for more detailed information on queries, extensions of status variables that are needed. SHOW PROFILE goes someway internally to indicate what’s going on, but knowing that a certain buffer is being used, and what portion of it per connection will help in sizing. It’s important for example to know the tmp_table_size actually used in a result set, VARCHAR and COLLATION have a huge effect that people simply don’t consider. As the number of Pluggable storage engines increases, the need to know what is really happening is going to be more important. Some of this may be more in relation to Real Time Query Monitoring, but I feel certain additional information is needed to be stored.
4. Online Table Maintenance
It was not until I had to time operations recently for ALTER TABLE ADD COLUMN|INDEX did I realize the extent of the time it takes for InnoDB tables (i.e. is takes your database table offline during this time for any OLTP). My tests were taking over an hour (and I was not in the 3 digit GB range for a table). A real uptime system can’t support downtime like this. Traditionally large scale out MySQL applications have been developed around this limitation, however to compete more with Enterprise experiences, and resources coming from enterprise background this is simply not an option. Add the fact you can’t add a datafile to a Innodb Tablespace online (why not!). While speaking of datafiles, I echo Frank’s comment with the limitation of when using innodb_file_per_table, you can’t copy the file between MySQL Instances (assuming for example all the same version of H/W, O/S, MySQL).
I really hope that Falcon addresses these issues to provide a transactional storage engine offering with these enterprise uptime features.
5. Published Benchmarks
MySQL does not publish any benchmarks, well at least not what I know about. The first problem is: how long is a piece of string. There are millions of variables, but it would be great if even a number of cases of straight forward cases were proven. People may then have a better indication of baseline systems.
Here is my initial wish list.
- Classification of Server Configuration. Let’s say a comparison between 1 CPU (dual Core), 2 CPU (dual Core) and 4 CPU (dual Core) commodity H/W. With the same memory (4G), disk (local disk), O/S (64 bit to support > 4GB), sample data (20-50GB) and same queries (simple OLTP only) just what are the benefits. Can we get a cost of throughput to $ Cost.
- Disk Configuration. Just how does local Raid 1/Raid 5/Raid 10, compare with SAN (Raid 5) and SAN (Raid 10). Ok there are many types of disks as well as Raid, but start with commodity SATA 72K, 8MB cache. In addition how does a machine with 6 drives (in Raid 1 with OS,Data,Logs split) compare with Raid 5 or Raid 10.
- RAM. How do our tests run when we take a 4GB system with 20-50GB of data and give it now 16GB.
- Backup/Recovery. How long does it take to backup and restore.
- Admin, how long does it take to ALTER TABLE, add data file, even something simply like how long to load data into a memory table across H/W has been interesting
As you can see it turns into a nightmare quickly, we didn’t talk about storage engines like MyISAM/InnoDB, tuning parameters, different O/S etc but surely something really is better then nothing. If only there was a baseline of data and queries to start with. Surely with the data sources available out there, some enterprising person could create a 20GB, 50GB + realistic production type data source, and 20-50 OLTP queries and we have a baseline.
There is talk of the Build Farm by Jay for compiling, let’s get that baseline so we can run some tests across thousands of configurations.
If sufficient work was done by MySQL to get some standard start, then the community might take up the challenge of taking the data/queries/benchmarking framework and test on all the configurations out there, tune to the wazoo and provide back to the MySQL Forge data for everybody to look at.
One day, knowing that this type of disk with this type of battery backup in this RAID configuration just isn’t anywhere near as good as 3 other types of options at roughly the same price.
There are more, but in keeping with the spirit of 5 knowing that at least 2 people have shown scope creep already I’ll stop. I really want to mention more.
More About Top 5
Jay Pipes started the Top 5 wishes for MySQL recently. Here are the Planet MySQL contributors to date.
Marten Mickos – MySQL CEO
It’s almost like a chain letter, so I’ll start it by passing it onto 3 more, my challenge is to: — Mike Kruckenberg, my evil(he isn’t really evil) twin – Roland Bouman & Paul McCullagh.
27 June 2007 Update
Since my posting we have also had: