Additional index on oc_preferences to make queries without a user filter faster

[juliushaertl]

Fixes #30421

IConfig methods may issue queries which are causing a full table scan on oc_preferences with using the existing primary key as an index as it is only partially filtered for in the where clause, as the order seems to be relevant (userid,appid,configkey)

server/lib/private/AllConfig.php

Lines 485 to 490 in c92ac34

	public function getUsersForUserValue($appName, $key, $value) {
	// TODO - FIXME
	$this->fixDIInit();
	$sql = 'SELECT `userid` FROM `*PREFIX*preferences` ' .
	'WHERE `appid` = ? AND `configkey` = ? ';

server/lib/private/AllConfig.php

Lines 387 to 392 in c92ac34

	public function deleteAppFromAllUsers($appName) {
	// TODO - FIXME
	$this->fixDIInit();
	$sql = 'DELETE FROM `*PREFIX*preferences` '.
	'WHERE `appid` = ?';

[PVince81]

👍

[PVince81]

seems the index has introduced ordering issues:

1) Test\AllConfigTest::testGetUsersForUserValue
Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
 Array (
-    0 => 'user1'
+    0 => 'user6'
     1 => 'user2'
-    2 => 'user6'
+    2 => 'user1'
 )

/drone/src/tests/lib/AllConfigTest.php:437

2) Test\AllConfigTest::testGetUsersForUserValueCaseInsensitive
Failed asserting that two arrays are identical.
--- Expected
+++ Actual
@@ @@
 Array &0 (
-    0 => 'user1'
-    1 => 'user2'
+    0 => 'user2'
+    1 => 'user1'
 )

/drone/src/tests/lib/AllConfigTest.php:458

[nickvergessen]

Postgres needs a sleep after each insert. Otherwise the input order is not the same as it's journaled at the meantime.

Also:

Conflicting files
core/Application.php
core/Command/Db/AddMissingIndices.php

[PVince81]

@juliushaertl can you finish this at some point, it looks interesting :-)

[juliushaertl]

Rebased and added an ORDER BY userid statement to the queries in question which is covered by the already used index and gives a fixed result ordering then.

[juliushaertl]

Another quick re-review on the order by statement would be appreciated before hitting merge ;) @nickvergessen @PVince81