Indexes too large for some tables with utf8mb4
after performing an update from an clean TYPO3 7.6.21 to 8.7.4 (maybe also when installing a clean 8.7.4) the Database Analyzer shows the following error:
Specified key was too long; max key length is 3072 bytes.
The query "CREATE INDEX `getDomainStartPage` ON `sys_domain` (pid, hidden, domainName)" fails, because domainName has varchar(80).
utf8 works, utf8mb4 not. I think varchar(80) should be raised or the index limited - https://github.com/TYPO3/TYPO3.CMS/blob/b66275c83818ddc02bda04ab67c53bf901cad54d/typo3/sysext/frontend/ext_tables.sql#L163.
What do you think? :)
Updated by Tymoteusz Motylewski over 4 years ago
Raising the domainName length will not make the issue disappear but will make it worse.
utf8mb4 uses 4 bytes per char, while "standard" utf8 collation uses 3 bytes per char.
This is why it fails on utf8mb4 and doesn't exceed the limit with plain utf8
Updated by Sybille Peters almost 4 years ago
What is the status on this?
Currently, if you want to use the (generally recommended) charset utf8mb4 for all tables, you can't because the indexes become too large (exceeds 1000 bytes).This is currently the case in TYPO3 8 for: