What is the maximum length of MySQL VARCHAR column?
The maximum row size for the used table type, not counting BLOBs, is For example, if you create a summary table that counts groups of rows, and you add a row to the source table, Flexviews simply increments the corresponding group by one.
MySQL currently does not have an appropriate data type for this, but you can use your own storage format: Stored Programs and Views.
Another surprise is that an ENUM field sorts by the internal integer values, not by the strings themselves:. Floating-point math is significantly faster, because the CPU performs the computations natively.
But in some high-volume cases it actually makes sense to use a BIGINT instead, and store the data as some multiple of the smallest fraction of currency you need to handle. Each Windows API function that takes a string actually comes in two versions.
An application that keeps counts in a table can run into concurrency problems when updating the counters. Specifying Character Sets and Collations. I work for GitHub. The following sizes assume the database is using the UTF-8 encoding.
MariaDB has microsecond-granularity temporal types. This is meaningless for most applications: The following will not find anything:. It takes advantage of the fact that row-based binary logging includes images of the rows before and after they are updated, so Flexviews can see not only the new value of each row, but the delta from the previous version, without even looking at the source table.
But you have to realize that this advantage is for disk storage only. Smaller data types are usually faster, because they use less space on the disk, in memory, and in the CPU cache. Again, this is an undocumented, unsupported technique. See my earlier post: User comments in this section are, as the name implies, provided by MySQL users. They also generally require fewer CPU cycles to process. This blogpost has been posted over two years ago.
Keep this in mind if you need to compare the result to another value. Sometimes you can use an ENUM column instead of conventional string types. Pros and Cons of a Normalized Schema. But it cannot describe Russian or Hebrew names. The only way we got any international communication done at all was to build standards on top of the common 7-bit ASCII subset. So we refine our table: For example: This also applies to local parameters within the stored routines.
Enabling strict SQL will enforce the maximum character lengths and truncate any entered data that exceeds those limits. As of mySQL 5.
About using UTF-8 fields in MySQL
Collations which end with "cs" or "bin" are case sensitive. Notify me of new comments via email. Sign Up Login You must be logged in to post a comment. All fixed-length data types uses all the bytes they were declared. None of the above character sets support all languages. So we refine our table:. Static tables use a bit in the row record for a flag that indicates whether the row has been deleted.