My company's infra team is converting our internal MYSQL databases from 5.7.x to 8.0 since 5.7 is approaching End of Life. With that comes a somewhat major deprecation of the utf8mb3 charset. We're formulating a plan that includes moving our larger VARCHAR fields to MEDIUMTEXT (and understand the implications with sync'ed records), however I have a few questions about some of the finer details related to Appian. utf8mb4 takes up to 4 bytes for storage instead of up to 3. When reading a VARCHAR field, does Appian always see the "maximum" size for a value when handling the 1mb limit? For example, does "asdf" under utf8mb3 count as 4 bytes or 12 bytes, considering that no upper unicode characters are used? When reading a VARCHAR field as part of a!queryRecordType , are there any differences between utf8mb3 and utf8mb4 as it relates to the 4,000 character limit on what's sync'ed into Appian? Any tips on successfully converting a VARCHAR database field to MEDIUMTEXT without breaking the record fields?

MySQL 5.8 utf8mb3 Deprecation

Jesse Knight

Certified Lead Developer

over 1 year ago

My company's infra team is converting our internal MYSQL databases from 5.7.x to 8.0 since 5.7 is approaching End of Life. With that comes a somewhat major deprecation of the utf8mb3 charset. We're formulating a plan that includes moving our larger VARCHAR fields to MEDIUMTEXT (and understand the implications with sync'ed records), however I have a few questions about some of the finer details related to Appian.

utf8mb4 takes up to 4 bytes for storage instead of up to 3.
- When reading a VARCHAR field, does Appian always see the "maximum" size for a value when handling the 1mb limit? For example, does "asdf" under utf8mb3 count as 4 bytes or 12 bytes, considering that no upper unicode characters are used?
- When reading a VARCHAR field as part of a!queryRecordType, are there any differences between utf8mb3 and utf8mb4 as it relates to the 4,000 character limit on what's sync'ed into Appian?
Any tips on successfully converting a VARCHAR database field to MEDIUMTEXT without breaking the record fields?

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0 Stefan Helzle
Certified Lead Developer
over 1 year ago

When changing the data type of a record field you might have to recreate the record field which leads to some effort as you would have to update all references in you applications.

But I suggest to contact Appian and discuss that plan with their experts.
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0 Mathieu Drouin
Certified Lead Developer
over 1 year ago

Appian themselves refer to utfmb4 for both MySQL and MariaDB installations. Dating back to 21.3 (and probably earlier).

I definitely recommend consulting with Appian on this but I really doubt that they will advise to convert from VARCHAR to MEDIUMTEXT.
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