Make reserve faster on DbQueue

[mikk150]

Q	A
Is bugfix?	yes
New feature?	no
Breaks BC?	no
Tests pass?	yes
Fixed issues	#280

[mikk150]

Mkay, this does not fix it... it makes it better, but ultimately it is still slow

Because of ORDER BY clause, it does not use index for some reason even if I add all fields that are used in ORDER BY or WHERE clause.. but I found out that when I change LIMIT 1 to LIMIT 100 it is fast for some bizarre reason(I literally have no idea why it does that)...

so, should I remove this LIMIT 1 and replace it with LIMIT 100 and rely on the fact that one()

[samdark]

That's super-weird. How could it be that selecting 1 record is slower than selecting 100 records?

[mikk150]

@samdark my findings there even were wrong. I am still trying to figure out how to make it so that it starts using indexes

[samdark]

It won't use index since it doesn't make sense to use index on two rows. Even full table scan will be faster.

[samdark]

Make it 5000 rows and check again.

[mikk150]

That is not the case..
If I remove order by clause then it is fast

[rob006]

I played with this some time ago and I've got much better performance with separate query for each priority (I have 3 priorities, so it was not a big deal) than one query with ORDER BY priority.

[mikk150]

@rob006 unfortunately yii2-queue supports more than 3 priorities... I would like to fix it once and for all, just as it should be fixed

[rob006]

unfortunately yii2-queue supports more than 3 priorities...

That depends on driver. Some of them support more priorities, some of them does not support priorities at all. There is no standard here.