The preFetchBlob method in Piwik_Archive_Single uses LIKE '$name%' to select subtable blobs w/ the main blob. Sometimes this can result in selecting the wrong blobs. For example, selecting blobs for 'Actions_actions' will select blobs for 'Actions_actions_url*' as well. This shouldn't happen.
(In ) Fixes #3311, use more granular SELECT in Piwik_Archive_Single::preFetchBlob & add test to make sure extra blobs are not selected.