Fixes #19462 - changed includes to preload

[ShimShtein]

No description provided.

[shlomizadok]

LGTM, pending Jenkins

[ares]

Thanks @ShimShtein, do you have some testing data or something where I could reproduce the issue? My understanding is that preload enforces always uses 2 SQL queries, while includes can fallback to LEFT OUTER JOIN in case there's some condition on the joined table. This change would make the base_scope limited in term of adding where with conditions on policies table. Also I was under impression, that include does the same things as preload (2 queries) as long as there's no such condition , so I wonder how this helps with memory consumption.

[iNecas]

FYI https://bugzilla.redhat.com/show_bug.cgi?id=1447958#c13 confirms this change really has impact on the memory. The issue seems to be that the include generates too big queries to the rdbms to handle

[ShimShtein]

@iNecas already stated the reason. If you want a bit more info, I have explained this issue in Katello's part of this chage here.

Basically, I didn't see a problem with policies, but I am not sure it couldn't create problems in some esoteric use case somewhere down the road. IMHO using preload (two queries) is justified, if there is a big degree of connectivity (many hosts are connected to the same small set of policies).

[ares]

Thanks @ShimShtein, works fine with hosts that have policies. I'm merging since it's unlikely that this would break testing. I'll fix them if that is the case :-)