Add extra DB constraints

[mizdebsk]

For better DB consistency we should add additional constraints.

KojiTask

state BETWEEN 0 AND 5
started IS NOT NULL
-- Not running tasks must have finished timestamp set
state = 0 OR state = 1 OR state = 4 OR finished IS NOT NULL
arch IS NOT NULL

Build

state BETWEEN 2 AND 5
task_id IS NOT NULL
started IS NOT NULL
-- Not running builds must have finished timestamp set
state <> 2 OR finished IS NOT NULL
-- Complete builds must have version set
state <> 3 OR version IS NOT NULL
-- Complete builds must have release set
state <> 3 OR release IS NOT NULL
-- Complete builds must have repo_id set
state <> 3 OR repo_id IS NOT NULL
-- Only running builds can have cancelation request
state = 2 OR NOT cancel_requested
-- Only builds with deps processed can have deps resolved
NOT deps_resolved OR deps_processed
-- Real builds must be complete
NOT real OR state = 3

[mizdebsk]

I ran these constrains against production database. Three of them are violated (all for Build table):

• started IS NOT NULL (2 builds violate this; both are real, complete builds)
• state <> 2 OR finished IS NOT NULL (not running builds must have finished timestamp set; 37 builds violate this)
• state <> 3 OR repo_id IS NOT NULL (complete builds must have repo_id set; violated by 907 builds)

[msimacek]

There's one more constraint I'd like to have - groups are currently joined with package on name, but it's missing foreign key constraint. It should be added.

[msimacek]

Almost everything has been added already, except:

• KojiTask timestamps - we weren't sure whether we can rely on them and they aren't used by anything, not even displayed
• cancel_request - cancelling koji builds is indempotent operation, I really think it's not worth compilcating both frontend and backend with locking for this

[mizdebsk]

I believe that there is nothing more left to do here. Closing.