… parallel processes heavily writing to database. Introduce Throttling Sometimes even single process overloads system too much in this case throttling by… a good idea. It also often helps with monopolizing replication thread. For example if I need to delete old data instead…
Post: Announcing Percona XtraBackup 2.0.0 GA
April 4, 2012 By 11 Comments
… with streaming backups + external (usually single-threaded) compression utilities, which also had a number of other limitations (e.g. could not be used… was required to uncompress the entire backup to restore a single table). Percona XtraBackup now supports streaming incremental backups. In previous…
Post: MySQL Limitations Part 1: Single-Threaded Replication
October 20, 2010 By 16 Comments
… series of blog posts on MySQL’s unsolved severe limitations. I mean limitations that really hobble it for major, important needs — not… wastefully compared to its potential. The first glaring problem is single-threaded replication. It is severe and getting much worse as servers… going to have to default to single-threaded as replication currently does, and only enable the multi-threaded behavior if the user configures…
Post: MySQL Limitations Part 4: One thread per connection
October 27, 2010 By 14 Comments
… MySQL handles connections, allocating one thread per connection to the server. MySQL is a single process with multiple threads. Not all databases are…, fundamental features — and it’s single-threaded and relies on the binary log, which are two major limitations. And it has subqueries, which…
Post: MySQL Limitations Part 2: The Binary Log
October 23, 2010 By 11 Comments
… what’s seriously limiting MySQL in certain circumstances (links: part 1). In the first part, I wrote about single-threaded replication. Upstream from… data in the server. The binary log is a real limitation in MySQL. The binary log is necessary not only for… or schema, but that’s a description of a pretty limited, clunky replication system from the user’s point of view…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
… pessimistic delete, if the page data size drops below this limit, merging it to a neighbor is tried */ #define BTR_CUR… read-aheads are performed in the Unix version with a single thread. Only one read-ahead can be happening on Unix at…_innodb.cc in 5.1: static MYSQL_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency, PLUGIN_VAR_RQCMDARG, “Helps in performance tuning in…
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
…. Using synchronous I/O mode Doing random read test Threads started! Time limit exceeded, exiting… Done. Operations performed: 773835 Read, 0 Write… –num-threads=1 –file-test-mode=rndrd run For single thread we get 259.28 Requests/sec which approximately matches what single drive can… for 1 thread and 605.88 Requests/sec for 64 threads. As you can see we got more writes for single thread than we…
Post: Thoughts on MySQL Replication
July 7, 2006 By 18 Comments
…. So what would be my list of limits and watch outs in this case ? – Limited write scaling. As Brian writes this works… their resources for replication (forget for the second replication being single thread, which just makes things worse), which means only 10% will… write load This is needed to avoid scalability problems of single thread and resource waste. I would call load light if it…
Post: Tokyo Tyrant -The Extras Part III : Write Bottleneck
November 12, 2009 By 3 Comments
… applications but it still single threads them when writing out to disk.  If you run several threads all just inserting into… second is the most this particular server is capable of ( single threaded ). Hopefully this is something that maybe able to be… into multiple tables each with there own cache. This limit is per TC DB so this should work. I…
Post: Managing Slave Lag with MySQL Replication
October 12, 2007 By 11 Comments
… those lag spikes: Slave Server Load – MySQL Replication goes in single thread so it is really vulnerable to the server load. If… is not the case – because MySQL Replication runs in single thread (two threads, but only one of them executes the query) it is… a lot to see when you’re close to the limit. To manage replication lag and to understand what is loading…
