For the stolen-relations project, we're doing some programmatic data-cleaning. I recently uploaded test sql to an empty database and examined the load in phpMyAdmin.
I noticed that the collation for the few updated tables had changed from the utf8mb4_unicode_520_ci encoding I've ensured all my sql tables use for the last few years. The updated tables are using the collation utf8mb4_0900_ai_ci.
So I asked chatGPT about the differences, and then did a few google searches to verify the info. Over time, I'll move collations to this utf8mb4_0900_ai_ci collation.
what are the pros and cons of mysql collation "utf8mb4_0900_ai_ci" vs "utf8mb4_unicode_520_ci"?
MySQL collations define the rules for comparing and sorting character strings in the database. Both "utf8mb4_0900_ai_ci" and "utf8mb4_unicode_520_ci" are collations for the utf8mb4 character set, which supports the full range of Unicode characters. However, they have different comparison rules based on different Unicode standards.
- Based on the Unicode 9.0 standard.
- AI (Accent Insensitive): It treats accented characters as equivalent to their unaccented counterparts, which can be useful when comparing text in languages with many accented characters.
- CI (Case Insensitive): It treats upper and lowercase versions of the same letter as equal, which simplifies text comparisons and searches.
Pros:
- More up-to-date and generally recommended for new applications.
- Provides better performance for sorting and searching, as it's optimized for the latest Unicode standards.
- Offers better support for supplementary characters outside the Basic Multilingual Plane (BMP).
Cons:
- Might not be fully compatible with older systems or applications that rely on specific behavior from older collations.
- Based on the Unicode 5.2 standard.
- CI (Case Insensitive): It treats upper and lowercase versions of the same letter as equal, which simplifies text comparisons and searches.
Pros:
- Can be more compatible with older systems or applications that rely on specific behavior from older collations.
Cons:
- Less up-to-date compared to the utf8mb4_0900_ai_ci collation, which means it may not support the latest Unicode features or optimizations.
- Does not offer accent insensitivity, which may lead to incorrect results in some text comparisons or searches involving accented characters.
In summary, utf8mb4_0900_ai_ci is generally the better choice for new applications due to its up-to-date support for Unicode standards, better performance, and accent insensitivity. However, utf8mb4_unicode_520_ci might be more suitable for older applications or systems that require specific behavior from an older collation.
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