![]() ![]() MySIAM, InnoDb or InnoDb with innodb_large_prefix enabled have differents key length limitation. ![]() It can be any of previous errors depending on what is the storage engine of the table. #1071 - Specified key was too long max key length is 3072 bytes #1071 - Specified key was too long max key length is 1000 bytes Below can be see examples of the errors: #1071 - Specified key was too long max key length is 767 bytes One my wondering how changing the charset affect the key length. Based on questions you've asked you need to look more into basic architecture and how the query engine(s) work.Welling Guzman's homepage Home Notes Photos About ContactĪfter switching the default charset from utf8 to utf8mb4 to support emojis on Directus, we started to receive errors that the key was too long. If you are having performance problems and are wondering if a datatype change will help, you're barking up the wrong tree. If you're worried about the performance impact of a single column's design, you're chasing a red herring here. There's no benefit to not matching your front-end.īut, umm. Match it to whatever your frontend allows (so it can error out at the application layer instead of the database). The only difference is how long a manuscript can be written in the comment field before it gets rejected by the database. The number in brackets is just defining the max length (5k vs 1b).Ī two letter "NC" comment is going to take 3 bytes either way, and most databases bottleneck on IO (which will typically be in 8k blocks anyway). Unless you have users that like to write novellas in comment fields. Like accepting non-terminated statements. Good habits and all that.ĮTA: I'm fully aware that this warning being MS specific means it could literally be decades for it's depreciated. I also think it might not be an ANSI data type, which means some DBs might not support it, making portability harder. (I wouldn't be surprised if text is more prone to slowdowns, because it could go super-wide long before varchar could.) Both text and varchar are dynamic length data types, so performance wise I wouldn't expect to see much difference at all, so I'd be inclined to err on the side of forward compatibility. The "text" datatype is on the chopping block for depreciation. Use nvarchar(max), varchar(max), and varbinary(max) instead. Avoid using these data types in new development work, and plan to modify applications that currently use them. The ntext, text, and image data types will be removed in a future version of SQL Server. Thanks to -sniff- for the awesome header image! You should post these to /r/learnsql instead. Note /r/SQL does not allow links to basic tutorials to be posted here. Please view the Wiki for online resources. Learning SQLĪ common question is how to learn SQL. SELECT count(a.field1), a.field2, SUM(b.field4) FROM a INNER JOIN b ON a.key1 = b.key1 WHERE a.field8 = 'test' GROUP by a.field1, a.field2 HAVING SUM(b.field4) > 5 ORDER by a.field.3įor those with SQL questions we recommend using SQLFiddle to provide a useful development and testing environment for those who wish to fully understand your problem and help devise a solution. Something as simple as line breaks and using reddit's built in code formatting (4 spaces at the start of each line) can turn this: This will greatly increase your chances of receiving the help you desire. If you are including actual code in a post or comment, please attempt to format it in a way that is readable for other users. We will gladly help where we can as long as you post the work you have already done or show that you have attempted to figure it out on your own. If you are a student or just looking for help on your code please do not just post your questions and expect the community to do all the work for you. While naturally we should endeavor to work as platform neutrally as possible many questions and answers require tailoring to the feature set of a specific platform. When requesting help or asking questions please prefix your title with the SQL variant/platform you are using within square brackets like so: The goal of /r/SQL is to provide a place for interesting and informative SQL content and discussions. ![]()
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