Workflow for generating deduplication indexes in Netarchivesuite

log.info("Snapshot harvest #{} activated. Requesting preparation of deduplicationIndex before jobgeneration can commence", harvestId);
Set<Long> jobSet = hdDaoProvider.get().getJobIdsForSnapshotDeduplicationIndex(harvestId);
jobIndexCache.requestIndex(jobSet, harvestId);

    /**
     * Get list of harvests previous to this one.
     *
     * @param thisHarvest The id of this harvestdefinition
     * @return a list of IDs belonging to harvests previous to this one.
     */
    private List<Long> getPreviousFullHarvests(Long thisHarvest) {
        List<Long> results = new ArrayList<Long>();
        try (Connection c = HarvestDBConnection.get();) {
            // Follow the chain of originating IDs back
            for (Long originatingHarvest = thisHarvest; originatingHarvest != null;
                // Compute next originatingHarvest
                 originatingHarvest = DBUtils.selectFirstLongValueIfAny(c, "SELECT previoushd FROM fullharvests"
                         + " WHERE fullharvests.harvest_id=?", originatingHarvest)) {
                if (!originatingHarvest.equals(thisHarvest)) {
                    results.add(originatingHarvest);
                }
            }

            // Find the first harvest in the chain (but last in the list).
            Long firstHarvest = thisHarvest;
            if (!results.isEmpty()) {
                firstHarvest = results.get(results.size() - 1);
            }

            // Find the last harvest in the chain before
            Long olderHarvest = DBUtils.selectFirstLongValueIfAny(c, "SELECT fullharvests.harvest_id"
                            + " FROM fullharvests, harvestdefinitions," + "  harvestdefinitions AS currenthd"
                            + " WHERE currenthd.harvest_id=?" + " AND fullharvests.harvest_id "
                            + "= harvestdefinitions.harvest_id"
                            + " AND harvestdefinitions.submitted " + "< currenthd.submitted"
                            + " ORDER BY harvestdefinitions.submitted " + HarvestStatusQuery.SORT_ORDER.DESC.name(),
                    firstHarvest);
            // Follow the chain of originating IDs back
            for (Long originatingHarvest = olderHarvest; originatingHarvest != null; originatingHarvest = DBUtils
                    .selectFirstLongValueIfAny(c, "SELECT previoushd FROM fullharvests"
                            + " WHERE fullharvests.harvest_id=?", originatingHarvest)) {
                results.add(originatingHarvest);
            }
        } catch (SQLException e) {
            log.warn("Exception thrown while updating fullharvests.isindexready field: {}",
                    ExceptionUtils.getSQLExceptionCause(e), e);
        }
        return results;
    }