Remove index on file_target of share table

[MorrisJobke]

• causes issues on InnoDB because it exceeds the maximal key length
  of an index which is 767 (3-byte charset * varchar(512) = 1536)
• fixes OC 8.0.5 -> 8.1.0 -> master update key too long error with Mariadb #17619

Replaces #17626

cc @karlitschek @DeepDiver1975 @PVince81

[scrutinizer-notifier]

A new inspection was created.

[DeepDiver1975]

👍

[PVince81]

👍

[karlitschek]

unfortunately 👍
At some point in time we have to think about DB specific indexes. It is sad that we can't do a lot of optimizations.

[PVince81]

The problem with files_target is that it is supposed to contain a full path.
Another approach would be to switch to using file ids for share targets, and have the mount points exist in the filecache table. See #14396

[ghost]

🚀 Test PASSed.🚀

[DeepDiver1975]

At some point in time we have to think about DB specific indexes. It is sad that we can't do a lot of optimizations.

We could have more fine granular access to the database schema using something like doctrine migrations.

On each migration step we could react individually on the database system allowing us to allow specific settings.

@karlitschek see #14851 for more details - happy to chat about the next steps

[karlitschek]

Hmm. Looks very interesting and promising. :-)