Bug #1546
Updated by Ori Rabin over 10 years ago
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