Add parent index on filecache

[artonge]

To speed up:

server/lib/private/Files/Cache/Cache.php

Lines 878 to 880 in fd2afe6

	$query->select('size', 'unencrypted_size')
	->from('filecache')
	->whereParent($id);

The current query uses the parent_name_hash index, which is not optimal with long names.

	id	select_type	table	type	possible_keys	key	key_len	ref	rows
Without index	1	SIMPLE	oc_filecache	ref	fs_parent_name_hash	fs_parent_name_hash	8	const	5
With index	1	SIMPLE	oc_filecache	ref	fs_parent_name_hash,oc_filecache_parent	oc_filecache_parent	8	const	5

[artonge]

/backport to stable25

[artonge]

/backport to stable24

[icewind1991]

Also needs to be added to the migration that creates the filecache table

[artonge]

Waiting for more practical feedbacks before moving on.

Addressed

[juliushaertl]

Can you outline or do you have a reference why the single index would be faster? At least from the explain there seems to be no difference.

[icewind1991]

Can you outline or do you have a reference why the single index would be faster? At least from the explain there seems to be no difference.

It seems that the size of the parent_name_hash index is causing performance issues

[szaimen]

/rebase

[juliushaertl]

Failure unrelated

[szaimen]

/backport to stable26