"tags": ['Mongodb', 'Index', 'Query'], "pages": 3, "time" : ISODate("2017-04-09T11:43:39.236Z") }, { "_id": ObjectId("58e1d2f0bb1bbc3245fa7572") "title": "MongoDB Query", "author": "eryueyang", "tags": ['Mongodb', 'Query'], "pages": 8, "time" : ISODate(...
For more query examples, seeQuery Documentsin the MongoDB manual. Match by Substring The following query filter uses the$regexoperator to find all documents where the value ofemailincludes the term "andrea_le": { email: { $regex: "andrea_le" } } ...
) { // return null; throw new IllegalArgumentException("not a query sql statement"); } MongoData mongo = new MongoData(); DBCursor c = null; SQLSelectStatement selectStmt = (SQLSelectStatement) statement; SQLSelectQuery sqlSelectQuery = selectStmt.getSelect().getQuery(); int icount = 0...
If a set contains a nested array element, the set expression does not descend into the nested array but evaluates the array at top-level. Name Description $allElementsTrue Returns true if no element of a set evaluates to false, otherwise, returns false. Accepts a single argument expression. ...
实例中,$match 用于获取 status = "A" 的记录,然后将符合条件的记录送到下一阶段 $group 中进行分组求和计算,最后返回 Results。其中,$match、$group 都是阶段操作符,而阶段 $group 中用到的 $sum 是表达式操作符。 在下面,我们通过范例分别对阶段操作符和表达式操作符进行详解。
测试程序点击这里下载。测试基于单个master的mongodb,后续测试发现,如果开启master/slave的话,写入速度非常不稳定,在向slave传送数据的时候写入速度下降50%到80%。还有就是mongodb随着并发的上升并没有带来写入速度上的提高,反而下降了一点,可能是因为读写锁的关系。
In regular expressions, the^character is an anchor that asserts the start of a line or string. When used in a regular expression pattern, it ensures that the matched substring begins at the beginning of the target string. To perform a “starts with” query in MongoDB using regular expression...
String format = reader.getFormatName().toLowerCase(); if(ArrayUtils.contains(IMAGE_FORMAT, format)) { formats.add(format); } } }catch (Exception ex) { // } //如果格式不合法,则直接返回 if(formats.isEmpty()) { try { imageInputStream.close(); ...
substring(property.indexOf(".") + 1); isCompositeColumn = true; } /* * if a composite key. "." assuming "." is part of * property in case of embeddable only */ else if (StringUtils.contains(property, '.')) { EntityType entity = metaModel.entity(m.getEntityClazz()); String...
throw new MongoException("Can't find a chunk! file id: " + id + " chunk: " + chunkNumber); } return (byte[]) chunk.get("data"); } 代码示例来源:origin: org.mongodb/mongo-java-driver portToUse = Integer.parseInt(hostToUse.substring(idx + 1)); } catch (NumberFormatException e)...