DB: some missing indices

[ArnyminerZ]

Purpose

Add missing indices to database

Short description

• Indexed Collection#ownerId.
• Indexed WebDavDocument#parentId
• Increased database version number

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.

[rfc2822]

The Collection pushTopic should also be an index, because we will search for a collection with a specific topic when we receive a push message. The index should probably be non-unique, although it's intended to be unique – but if it's not for some reason, it shouldn't interfere with other functionality (and prevent having multiple collections with different URLs and same push topic, for instance).

[sunkup]

What @rfc2822 said :)

[rfc2822]

Hm, compilation of the tests still shows this message (in the assembleDebug step):

w: [ksp] /home/runner/work/davx5-ose/davx5-ose/app/src/main/kotlin/at/bitfire/davdroid/db/WebDavDocument.kt:33: parentId column references a foreign key but it is not part of an index. This may trigger full table scans whenever parent table is modified so you are highly advised to create an index that covers this column.

@ArnyminerZ Do you have an idea where this could come from?

[rfc2822]

After a rebase, the message is still there:

w: [ksp] /home/runner/work/davx5-ose/davx5-ose/app/src/main/kotlin/at/bitfire/davdroid/db/WebDavDocument.kt:33: parentId column references a foreign key but it is not part of an index. This may trigger full table scans whenever parent table is modified so you are highly advised to create an index that covers this column.

[ArnyminerZ]

I've tried everything that came up to my mind, and this is the only thing that works. I don't know if it's a bug, or if it's supposed to be this way, but the warning should be gone.

[ArnyminerZ]

Working on the failing tests

[rfc2822]

I think this would forbid the same file name ("README") to be present in different directories/mounts. We should keep the original index, if possible.

Above two foreign keys with childColumn=mountId and childColumn=parentId are defined. ForeignKey docs say:

It is also recommended to create an index on the child table to avoid full table scans when the parent table is modified. If a suitable index on the child table is missing, Room will print RoomWarnings. MISSING_INDEX_ON_FOREIGN_KEY_CHILD warning.

So we need two indices:

• mountId (will be used to find the children when a WebDavMount is deleted) – this is already covered by the Index("mountId", "parentId", "name", unique = true) index because it's the leftmost column, and
• parentId (will be used to find the children when a WebDavDocument is deleted).

It should be enough to just add a normal index about parentId.

[rfc2822]

Looks good, works and all warnings gone :)