report::expire is causing me issues, one of which is its very slow to run (~20 minutes, and thats before it ultimately errors).

Ohad believes this is due to table scans:

Ok, one simple thing that I found out, was that we were using the
following query:

Report Load (16588.0ms) SELECT id FROM `reports` WHERE (reports.id

= 0) AND (created_at < '2011-06-16 14:13:02') ORDER BY reports.id ASC

LIMIT 1000

if you run the following query in mysql console using explain:

explain SELECT id FROM `reports` WHERE (reports.id >= 0) AND
(created_at < '2012-06-16 14:13:02') ORDER BY reports.id ASC LIMIT
1000;

You would see that the query was forced to scan the entire reports
table and was not using the indexes.

it should be a "bit" faster to change from created_at to reported_at
(as created_at has no index at all).
I assume that the reason why using the older code was better for you
(as it was using reported_at which has an index) and using the in
batches was just a side effect.

we need to figure out the correct index for making this process a bit
faster, in my limited tests, creating index on multiple columns (id
and reported_at) were not very helpful.

in your case, creating an index is not trivial (as you have a large
set of data) as the indexes usually locks the db.

https://groups.google.com/d/msg/foreman-users/_Mn4oxXmP7E/T3ByUZ9YTcIJ