Fixed #27321 -- Added detection for table case name sensitivity on MySQL

[adamchainz]

It depends on the value of the lower_case_table_names setting, plus the case sensitivity of the filesystem that the table is on.

[adamchainz]

Ticket

[adamchainz]

This works but it's not strictly true. The description for the feature is:

Does the backend consider quoted identifiers with different casing to be equal?

MySQL is not case sensitive for many kinds of quotable identifiers, as per the docs:

Column, index, stored routine, and event names are not case sensitive on any platform, nor are column aliases.

It's just table names that are case sensitive, depending on the filesystem.

In practice Django is only using ignores_quoted_identifier_case for table name case sensitivity. I suggest renaming it to ignores_table_name_case - is this acceptable since it's not part of the public API?

[timgraham]

Omit 5.7 in the URL, although this URL is the first result for searching "LOWER_CASE_TABLE_NAMES MySQL" so maybe there's not much value?

[adamchainz]

I didn't know you could skip the version number from the url's, nice.

Maybe there isn't much value, but I hope it's useful for review at least

[timgraham]

Not sure about renaming the feature (added in c2e62fd). Any opinion @charettes?

[charettes]

Since the flag is only part of 1.10 and describes more accurately the checks we perform against it I wouldn't be opposed to rename it.

[adamchainz]

Should I add a deprecation shim or are database backends too internal to be subject to the deprecation policy?

[charettes]

@adamchainz I don't think a shim is required. If a third party database backend was relying on this flag the tests for this feature will fail and they'll be pointed in the right direction. What do you think @manfre?

[timgraham]

We could add the change in the "Database backend API" section of the backwards-incompatibel changes in the release notes. That said, a Google search for ignores_quoted_identifier_case doesn't give any results showing that this feature is used in backends outside of Django.

[timgraham]

This goes in "Backwards-incompatible changes" not "MInor features".

[adamchainz]

Woops thx.

[manfre]

A bit late, but the release notes are plenty for the rename, especially since it doesn't appear that it is in use (at least for the open sourced backends).

[adamchainz]

Thx @manfre