private long getAttributeCreateTimeThresholdEpochMs() {
        final Duration deleteAge = metaValueConfigProvider.get()
                .getDeleteAge()
                .getDuration();
        return System.currentTimeMillis() - deleteAge.toMillis();
    }
@return The oldest data attribute that we should keep
stroom-meta/stroom-meta-impl-db/src/main/java/stroom/meta/impl/db/MetaValueDaoImpl.java