… non-NULL fields) has 1 or 2 bytes of length, etc, even for fixed-length fields. * Each row has (used to have) 29…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
…select sum(data_length+index_length) from information_schema.tables where engine=’memory’; +——————————-+ | sum(data_length+index_length) | +——————————-+ | 126984 | …and when it can be found and fixed. This is where your MySQL Support …
Comment: Introducing new type of benchmark
February 25, 2012 By 16 Comments
… high and queue will get full and benchmark essentially fail. Fixing number of variables is another interesting question. It is one… of threads or fixed number of threads would make sense. I would see benchmark to set maximum queue length and maximum amount… injection rate and run time. When we have maximum queue length reached the transactions are “failed”. Our guidance for “pass” for…
Post: Dynamic row format for MEMORY tables
September 6, 2011 By 3 Comments
… before any non-key variable-length columns. For performance reasons, the key columns are stored in a fixed-length block at the beginning…. If there were any variable-length column in between them, it had to be stored in the fixed-length format, either wasting space… with this patch–for the fixed-length records too. Default sysbench 0.4.12 schema, one client thread: Fixed-row format (FRF, Percona…
Post: Innodb row size limitation
April 7, 2011 By 11 Comments
… length columns, and each exceeds 768 bytes, then you’ll have at least 8448 bytes for local storage, not counting other fixed length… may just have a table with 50 variable length columns, but if their max length is, say 50 bytes, you still have… level. This will always work (unless you have so many fixed length columns that you still exceed 8000 bytes, but in that…
Post: How number of columns affects performance ?
September 28, 2009 By 10 Comments
… tinyint columns. The former two tables have the same row length but have number of column different 50 times. Finally I… NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 This table has row length of 20 (which was a bit of surprise to me… TEXTs/BLOBs is fixed length when it is being processed). This conversion process depends on number of columns while for fixed rows the…
Post: Trailing spaces in MySQL
November 27, 2006 By 6 Comments
… the same, only being difference in the sense of fixed or dynamic row length used. Trailing spaces were removed in both cases… more. Well in reality CHAR columns are padded to full length with spaces but it is invisible as those trailing spaces… trailing spaces stored choosing VARCHAR vs CHAR in addition to fixed length vs dynamic level rows and space spent for column size…
Comment: Countless storage engines
May 4, 2007 By 6 Comments
… far as I understand really applies to “Variable length” row portion – the fixed length portion still needs to be updated to link to… version. I think the assumption in PBXT is to have fixed row portion small and so this file fits in memory…
Post: Getting MySQL to use full key length
January 31, 2007 By 5 Comments
… matches significant amount of rows). I think optimizer should be fixed to always expand and use “range” lookup at least for…. So how do you force MySQL optimizer to use full length in this case ? ANALYZE TABLE does not help, at least… (A,D) using only first keypart of that index. To fix this problem I guess another statistics alignment should take place…
Comment: Enum Fields VS Varchar VS Int + Joined table: What is Faster?
April 20, 2008 By 27 Comments
16 bit fixed length integers vs random length strings (32 to 400 bits) Shouldn’t the enum be several orders of magnitude faster, especially on sorts? I don’t understand. Please explain to me why the benchmark shows only negligible differences.
