想要遍历 mongoDB 的一半并使用另一个查询遍历其余的一半

Question

我收到此错误：

Exception in thread "main" com.mongodb.MongoCursorNotFoundException: Query failed with error code -5 and error message 'Cursor 304054517192 not found on server mongodb2:27017' on server mongodb2:27017 at com.mongodb.operation.QueryHelper.translateCommandException(QueryHelper.java:27) at com.mongodb.operation.QueryBatchCursor.getMore(QueryBatchCursor.java:215) at com.mongodb.operation.QueryBatchCursor.hasNext(QueryBatchCursor.java:103) at com.mongodb.MongoBatchCursorAdapter.hasNext(MongoBatchCursorAdapter.java:46) at com.mongodb.DBCursor.hasNext(DBCursor.java:155) at org.jongo.MongoCursor.hasNext(MongoCursor.java:38) at com.abc.Generator.Generate(Generator.java:162) at com.abc.main.main(main.java:72)

我认为是因为查询运行太久了。
所以我打算使用 find() 查询 mongo 并遍历一半的集合。
然后我想使用另一个 find() 查询并遍历剩下的一半集合。

请问如何直接把光标放在集合的一半位置？ The documentation does not seem to provide 它的任何功能。

我基本上只是使用 find() 并遍历包含 100000 条记录的集合，同时通过 ssh 连接到服务器。

MongoCollection history = jongo.getCollection("historyCollection");
MongoCursor<MyClass> allHistories = history.find().as(MyClass.class);

  //---Iterate thru all histories
  while (allHistories.hasNext()) {
  MyClass oneHistory = allHistories.next();
}

Answer 1

通过让 Mongo 集合按 ObjectId 的时间戳排序解决了这个问题。这样，我就能够使用大于运算符来查找 objectID 并拆分迭代。

private MongoCursor<PersonDBO> ReadFewProfilesFromDB(final String objectIdAfterWhichToSearchFrom, final Integer FIND_LIMIT) {

    MongoCursor<PersonDBO> aBatchOfProfiles = null;

    try {
        if (objectIdAfterWhichToSearchFrom.equals(START_OBJECTID_OF_MONGO_BATCHES)) {
            aBatchOfProfiles = personProfile.find().limit(FIND_LIMIT).as(PersonDBO.class);
        } else {
            aBatchOfProfiles = personProfile.find("{_id: {$gt: #}}", new ObjectId(objectIdAfterWhichToSearchFrom)).limit(FIND_LIMIT).as(PersonDBO.class);
        }
    } catch(Exception e) {logger.error("Problem while trying to find {} personProfiles, starting from objectID {}. {}, {}", FIND_LIMIT, objectIdAfterWhichToSearchFrom, e.getMessage(), e.getCause());}

    if (aBatchOfProfiles == null) {
        logger.error("profiles collection is null. Nothing more to iterate OR there was an exception when finding profiles. If exception, there would be an error printed above.");
        return null;
    }         

    return aBatchOfProfiles;
}

想要遍历 mongoDB 的一半并使用另一个查询遍历其余的一半

Want to iterate through half of mongoDB and iterate through the rest of the half with another query

java

mongodb

jongo