Comment 5 for bug 314621

The above query should be using CodeImportResult rather than CodeImport of course...

You can similarly prune all-but-the-last-N CodeImportResult rows entirely in a similar fashion:

store.execute("""DELETE FROM CodeImportResult
WHERE
code_import = %s
AND date_created < CURRENT_TIMESTAMP AT TIME ZONE 'UTC' - interval '60 days'
AND id NOT IN (
    SELECT id FROM CodeImportResult
    WHERE code_import = %s
    ORDER BY id DESC
    LIMIT %s)""" % (codeimportresult.code_import, codeimportresult.code_import, N))