In the past life was easy in MySQL. Both CHAR and VARCHAR types meant the same, only being difference in the sense of fixed or dynamic row length used. Trailing spaces were removed in both cases.
With MySQL 5.0 however things changed so now VARCHAR keeps trailing spaces while CHAR columns do not any more. Well in reality CHAR columns are padded to full length with spaces but it is invisible as those trailing spaces are removed upon retrieval. This is something you need to watch both upgrading to MySQL 5.0 as well as designing your applications – you should keep into account if you mind trailing spaces stored choosing VARCHAR vs CHAR in addition to fixed length vs dynamic level rows and space spent for column size counter.
There is more fun stuff with trailing spaces. When comparison is done trailing spaces are always removed, even if VARCHAR column is used which is pretty counterintuitive. So “a “=”a”=”a ” for all textual column types – CHAR, VARCHAR, TEXT. BLOB is exception it will preserve trailing spaces and use them in comparison.
Percona’s widely read Percona Data Performance blog highlights our expertise in enterprise-class software, support, consulting and managed services solutions for both MySQL® and MongoDB® across traditional and cloud-based platforms. The decades of experience represented by our consultants is found daily in numerous and relevant blog posts.
Besides specific database help, the blog also provides notices on upcoming events and webinars.
Want to get weekly updates listing the latest blog posts? Subscribe to our blog now! Submit your email address below.