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Peter ZaitsevAssume you’re running MySQL with Innodb tables and you’ve got crappy hardware, driver bug, kernel bug, unlucky power failure or some rare MySQL bug and some pages in Innodb tablespace got corrupted. In such cases Innodb will typically print something like this: InnoDB: Database page corruption on disk or a failed InnoDB: file read of […]
We were chatting with Jeremy Cole today and he brought to my attention last version of MySQL Community Eddition (5.0.51) was released in November 2007 – over 7 months ago. MySQL 5.0.51a and MySQL 5.0.51b security fixes were released but these can’t be considered proper releases. If we look at the old Kaj’s Announcement we […]
I have been helping customer today to resolve his lockups in production by downgrading from MySQL 5.1.25 to 5.0 We have other customers (and our own projects as well) which run on MySQL 5.1 successfully but I can’t it is on par with MySQL 5.0 stability yet. This given customer was running MyISAM on FreeBSD […]
Sometimes MySQL Replication may run out of sync – because of its own buts or operational limitations or because of application mistake, such as writing to the slave when you should be only writing to the master. In any case you need slave to be synced with Master. To discover the difference between Master and […]
I spent Monday and Tuesday this week on Velocity Conference It was quite interesting event worth attending and it was very good to see the problems in this are going beyond Apache, PHP, Memcache and MySQL. A lot of talks on this conference was focusing on what is called “FrontEnd”. The meaning of Frontend is […]
I should have written about it a while ago but I never had a change. I’m speaking at Velocity conference taking place in the Bay Area 23-24 of June. At the same conference we will have a book signing event for our book High Performance MySQL 2nd Edition which is finally in printing and should […]
We know MySQL Backups using LVM are pretty cool (check out mylvmbackup) or MMM though it is quite typical LVM is not configurable properly to be usable for MySQL Backups. Quite frequently I find LVM installed on the system but no free space left to be used as snapshot undo space, which means LVM is […]
Backing up MySQL Database most people compress them – which can make a good sense in terms of backup and recovery speed as well as space needed or be a serious bottleneck depending on circumstances and approach used. First I should mention this question mainly arises for medium and large size databases – for databases […]
I already wrote about some MySQL Error Messages which are confusing, here is one more:
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080603 20:53:10 [Note] Slave: connected to master '[email protected]:3306',replication resumed in log 'master-bin.003676' at position 444286437 080603 20:53:10 [Note] Slave: received end packet from server, apparent master shutdown: 080603 20:53:10 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'master-bin.003676' position 444292333 080603 20:53:10 [Note] Slave: connected to master '[email protected]:3306',replication resumed in log 'master-bin.003676' at position 444292333 080603 20:53:10 [Note] Slave: received end packet from server, apparent master shutdown: 080603 20:53:10 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'master-bin.003676' position 444294573 080603 20:53:10 [Note] Slave: connected to master '[email protected]:3306',replication resumed in log 'master-bin.003676' at position 444294573 080603 20:53:10 [Note] Slave: received end packet from server, apparent master shutdown: 080603 20:53:10 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'master-bin.003676' position 444298239 080603 20:53:10 [Note] Slave: connected to master '[email protected]:3306',replication resumed in log 'master-bin.003676' at position 444298239 |
After setting up new slave Server I’m getting error log file flooded with messages like this and there is no hint in the message what would explain what is wrong. In fact the issue in this case is (because […]
I was working with the customer today investigating MySQL over DRBD performance issues. His basic question was why there is so much overhead with DRBD in my case, while it is said there should be no more than 30% overhead when DRBD is used. The truth is – because how DRBD works it does not […]
There are some tools we commonly use doing performance review and optimization and we often ask each other where that particular stuff is located on the web or what is exactly name of the command what does that. Initially I thought creating internal Percona Wiki page, but thought there is no reason this information should […]
MySQL Server does not require you to specify name of the index if you’re running ALTER TABLE statement – it is optional. Though what might be good practical reasons to specify the key name or omit ? Things what you should be looking at is how MySQL names indexes automatically as well as what maintaining […]
I’m not big fan on flow control functions like IF or CASE used in MySQL Queries as they are often abused used to create queries which are poorly readable as well as can hardly be optimized well by MySQL Optimizer. One way I find IF statement very useful is computing multiple aggregates over different set […]
Sometimes due to programming error or due to very complex query you can get your PHP script running too long, well after user stopped waiting for the page to render and went browsing other sites. Looking at Server-Status I’ve seen scripts executing for hours sometimes which is obviously the problem – they take Apache Slot, […]
Quite frequently I would log in to customers system and find MySQL using too much memory. I would look at memory consumed by Innodb (it is often higher than innodb_buffer_pool_size) substract memory used by other global buffers such as query_cache_size and key_buffer and will in many cases see some mysterous memory which I can’t really […]
Looking at Kaj’s Blog Annoucement MySQL has pulled back on the plans to release portions of the servers as close Source only. I am extremely happy to hear these news ! This is good for MySQL as a company, MySQL customers and MySQL users. I’m hoping Community feedback was serious contributer to this decision, though […]
As you know we love to analyze performance of various MySQL features, benchmark, compare, analyze things and post our findings on MySQL Performance Blog. However recently we got too busy with serving out customers and the backlog of things to take a look and write about is just growing larger and larger. So we decided […]
In the previous post I mentioned a way I use to preload Clustered Index (data) for Innodb tables. Though I thought this topic would benefit from a bit more information. But lest first start with feature request for Innodb Team: All ways I mention here are hacks and they can’t be as efficient as native […]
Recently I was working with the customer who need quick warmup – to get Innodb table fetched in memory as fast as possible to get good in memory access performance. To do it I run the query: “SELECT count(*) FROM tbl WHERE non_idx_col=0” I use this particular form of query because it will do full […]
Sun is aggressively pushing T2000 as Scalable MySQL Platforms, and indeed it is Scalable in terms of high concurrency workloads – it is able to execute a lot of concurrent threads and so speed gain from 1 thread to say 32 thread will be significant. But thing a lot of people miss is – Being […]