使用 Java 客户端 API 在 MarkLogic 中获取所有文档 URI

Question

i am trying to fetch all the documents from a database without knowing the exact url's . I got one query

DocumentPage documents =docMgr.read();
while (documents.hasNext()) {
    DocumentRecord document = documents.next();
    System.out.println(document.getUri());
}

But i do not have specific urls , i want all the documents

Answer 1

The first step is to enable your uris lexicon on the database.

You could eval some XQuery and run cts:uris() (or server-side JS and run cts.uris()):

    ServerEvaluationCall call = client.newServerEval()
        .xquery("cts:uris()");
    for ( EvalResult result : call.eval() ) {
        String uri = result.getString();
        System.out.println(uri);
    }

Two drawbacks are: (1) you'd need a user withprivileges and (2) there is no pagination.

If you have a small number of documents, you don't need pagination. But for a large number of documents pagination is recommended. Here's some code using the search API and pagination:

    // do the next eight lines just once
    String options =
        "<options xmlns='http://marklogic.com/appservices/search'>" +
        "  <values name='uris'>" +
        "    <uri/>" +
        "  </values>" +
        "</options>";
    QueryOptionsManager optionsMgr = client.newServerConfigManager().newQueryOptionsManager();
    optionsMgr.writeOptions("uriOptions", new StringHandle(options));

    // run the following each time you need to list all uris
    QueryManager queryMgr = client.newQueryManager();
    long pageLength = 10000;
    queryMgr.setPageLength(pageLength);
    ValuesDefinition query = queryMgr.newValuesDefinition("uris", "uriOptions");
    // the following "and" query just matches all documents
    query.setQueryDefinition(new StructuredQueryBuilder().and());
    int start = 1;
    boolean hasMore = true;
    Transaction transaction = client.openTransaction();
    try {
        while ( hasMore ) {
            CountedDistinctValue[] uriValues =
                queryMgr.values(query, new ValuesHandle(), start, transaction).getValues();
            for (CountedDistinctValue uriValue : uriValues) {
                String uri = uriValue.get("string", String.class);
                //System.out.println(uri);
            }
            start += uriValues.length;
            // this is the last page if uriValues is smaller than pageLength
            hasMore = uriValues.length == pageLength;
        }
    } finally {
        transaction.commit();
    }

The transaction is only necessary if you need a guaranteed "snapshot" list isolated from adds/deletes happening concurrently with this process. Since it adds some overhead, feel free to remove it if you don't need such exactness.

Answer 2

find out the page length and in the queryMgr you can specify the starting point to access. Keep on increasing the starting point and loop through all the URL. I was able to fetch all URI. This could be not so good approach but works.

List<String> uriList = new ArrayList<>();       
        QueryManager queryMgr = client.newQueryManager();
        StructuredQueryBuilder qb = new StructuredQueryBuilder();
        StructuredQueryDefinition querydef = qb.and(qb.collection("xxxx"), qb.collection("whatever"), qb.collection("whatever"));//outputs 241152
        SearchHandle results = queryMgr.search(querydef, new SearchHandle(), 10);
        long pageLength = results.getPageLength();
        long totalResults = results.getTotalResults();
        System.out.println("Total Reuslts: " + totalResults);
        long timesToLoop = totalResults / pageLength;
        for (int i = 0; i < timesToLoop; i = (int) (i + pageLength)) {
            System.out.println("Printing Results from: " + (i) + " to: " + (i + pageLength));
            results = queryMgr.search(querydef, new SearchHandle(), i);
            MatchDocumentSummary[] summaries = results.getMatchResults();//10 results because page length is 10
            for (MatchDocumentSummary summary : summaries) {
//                System.out.println("Extracted friom URI-> " + summary.getUri());
                uriList.add(summary.getUri());
            }
            if (i >= 1000) {//number of URI to store/retreive. plus 10
                break;
            }
        }
         uriList= uriList.stream().distinct().collect(Collectors.toList());
        return uriList;