BytesRef pendingOutput = fst.outputs.getNoOutput();
        fst.getFirstArc(scratchArc);
        BytesRef matchOutput = null;

        int index = 0;
        while (start + index < src.length) {
            final int codePoint = Character.codePointAt(src, start + index, src.length);
            if (fst.findTargetArc(ignoreCase ? Character.toLowerCase(codePoint) : codePoint, scratchArc, scratchArc, fstReader) == null) {

        }

        public E get(final int index) {
            return parent.get(index);
        }

        public E set(final int index, final E element) {
            return parent.set(index, element);
        }

        public void add(final int index, final E element) {
            parent.add(index, element);
        }

        public E remove(final int index) {
            return parent.remove(index);

 * This class manages the process of updating the search index with documents from
 * data stores, including bulk operations, document transformation, and error handling.
 */
public class IndexUpdateCallbackImpl implements IndexUpdateCallback {
    private static final Logger logger = LogManager.getLogger(IndexUpdateCallbackImpl.class);

    /**
     * Default constructor for index update callback implementation.

        }

        public E get(final int index) {
            return parent.get(index);
        }

        public E set(final int index, final E element) {
            return parent.set(index, element);
        }

        public void add(final int index, final E element) {
            parent.add(index, element);
        }

        public E remove(final int index) {
            return parent.remove(index);

## Pre-Migration Planning

### 1. Assessment Phase

Before starting migration, assess your current system:

- **Document Count**: Total number of indexed documents
- **Index Size**: Storage requirements for search indices
- **Crawl Sources**: URLs, file shares, databases being indexed
- **Custom Configurations**: URL patterns, security rules, metadata fields
- **Search Features**: Facets, suggestions, security filtering, ranking rules

						<c:forEach var="item" varStatus="s" items="${popularWords}">
							<c:if test="${s.index < 3}">
								<la:link
									href="/search?q=${f:u(item)}${fe:facetQuery()}${fe:geoQuery()}">${f:h(item)}</la:link>
							</c:if>
							<c:if test="${3 <= s.index}">
								<la:link styleClass="d-none d-sm-inline-block"

						<c:forEach var="item" varStatus="s" items="${popularWords}">
							<c:if test="${s.index < 3}">
								<la:link
									href="/search?q=${f:u(item)}${fe:facetQuery()}${fe:geoQuery()}">${f:h(item)}</la:link>
							</c:if>
							<c:if test="${3 <= s.index}">
								<la:link styleClass="d-none d-sm-inline-block"

import org.codelibs.fess.opensearch.config.exentity.DataConfig;
import org.codelibs.fess.util.ComponentUtil;
import org.opensearch.index.query.BoolQueryBuilder;
import org.opensearch.index.query.QueryBuilder;
import org.opensearch.index.query.QueryBuilders;

/**
 * Helper class for managing data crawling operations in Fess.
 * This class coordinates the execution of data store crawling processes,

        final String index = fessConfig.getIndexDocumentUpdateIndex();
        return deleteBySessionId(searchEngineClient, index, sessionId);
    }

    /**
     * Deletes all documents associated with the specified session ID from the given index.
     *
     * @param searchEngineClient the search engine client to use for deletion
     * @param index the index name to delete documents from

        final String index = "fess_basic_config";
        final ZipEntry entry = new ZipEntry(id + "/fess_basic_config.bulk");
        try {
            zos.putNextEntry(entry);
            SearchEngineUtil.scroll(index, hit -> {
                final String data = "{\"index\":{\"_index\":\"" + index + "\",\"_id\":\"" + StringEscapeUtils.escapeJson(hit.getId())