query:      `SELECT date_diff(month, '2010-01-01T', '2010-05T') FROM S3Object LIMIT 1`,
			wantResult: `{"_1":4}`,
		},
		{
			name:       "date_diff_month_oney",
			query:      `SELECT date_diff(month, '2010T', '2011T') FROM S3Object LIMIT 1`,
			wantResult: `{"_1":12}`,
		},
		{
			name:       "date_diff_month_neg",
			query:      `SELECT date_diff(month, '2011T', '2010T') FROM S3Object LIMIT 1`,

				// errors upwards.
				return nil, dmTime, errFileNotFound
			}
			return nil, dmTime, errUnsupportedDisk
		}
		return nil, dmTime, err
	}

	if discard {
		// This discard is mostly true for DELETEEs
		// so we need to make sure we do not keep
		// page-cache references after.
		defer disk.Fdatasync(f)
	}

	defer f.Close()

	// Get size for precise allocation.