…century and instead wanted a modular system where the storage engines themselves …the FRM file. What is an FRM file? It’s the FoRM file from UNIREG….count > 255) { my_message(ER_TOO_MANY_FIELDS, ER(ER_TOO_MANY_FIELDS), MYF(0)); DBUG_RETURN…just says “Can’t create table ‘test.t’ (errno: 139)”. This is …
Post: Is your MySQL buffer pool warm? Make it sweat!
April 16, 2013 By 6 Comments
…There are numerous solutions for MySQL high availability. Many rely on MySQL’s asynchronous replication to… /dev/null, and only have a log file for debugging purposes. Streaming logs from stdin… production systems. We restored a production database backup to our test database so that our test database…
Post: MySQL File System Fragmentation Benchmarks
March 21, 2008 By 28 Comments
Few days ago I wrote about testing writing to many files and seeing how this affects sequential read performance. I was … times. This could be because ext3 does not like so many files in directory or because random updates to 10000 distinct pages… is close, the difference is perhaps explained by the fact files needed to be constantly extended (meta data updates) and reopened…
Post: How innodb_open_files affects performance
November 18, 2009 By 4 Comments
… similar variable – innodb_open_files which defines how many files Innodb will keep open while working in innodb_file_per_table mode. Unlike MyISAM… local file system – one can open/close file hundreds of thousands times per second. To verify this I tried doing “open table” test for…
Post: MySQL 5.5 and MySQL 5.6 default variable values differences
February 21, 2013 By 8 Comments
…very welcome change to help workloads with many connects/disconnects sync_relay_log_info …and closing files is expensive operation (such as using MySQL on NFS file system). innodb_data_file_… can play with: mysql [localhost] {msandbox} (test) > select * from var55 where variable_name=’OPTIMIZER_SWITCH…
Post: Working with many files and file system fragmentation
March 18, 2008 By 11 Comments
… a test – creating 100 files writing 4K in the random file for some time and when checking the read speed on the files we… read single file at 80MB/sec while fragmented files only deliver about 2MB/sec – this is a massive difference. The test was done on EXT3 and it looks like it does not do very good job preventing file fragmentation for…
Post: Evaluating IO subsystem performance for MySQL Needs
March 5, 2008 By 23 Comments
…cached mode you can get better performance by having many outstanding requests. Running with more than one threads you…system evaluation benchmark Removing test files… [root@DB10 sysbench]# ./sysbench –test=fileio –max-time=60 –max-requests=1000000 –file-num=128 –file-extra-flags=direct –file…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…,2) Foreign key constraint fails for table `test/child`: , CONSTRAINT `child_ibfk_1` FOREIGN KEY (`…shows how many inserts were done in insert buffer, how many recs were merged and how many merges … amount of bytes Innodb has written in log files since system tablespace creation. You can also see …
Post: Disaster: LVM Performance in Snapshot Mode
February 5, 2009 By 55 Comments
… there are about twice as many writes as reads. SMALL FILE RUN When I decided to…test=fileio –num-threads=1 –init-rng=on –max-time=60 –file-num=1 –file-total-size=64M –file-extra-flags=direct –file-test… some time and I would expect any system doing writes to experience the “performance shock” …
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
… case offset is correct, but file system is unaware how to align files properly. 4. Partition table and file system properly aligned; sunit/swidth set… were all scripted and oltp benchmarks would automatically start after file tests so if there was an error in the setting, it… setting might be a [mirrored] RAID0 with many more stripes as not having proper file system alignment should have really interesting effects. Large…
