"history store table on-disk size": 0, "history store table out-of-order resolved updates that lose their durable timestamp": 0, "history store table out-of-order updates that were fixed up by moving existing records": 0, "history store table out-of-order updates that were fixed up du...
对于索引集合,索引字段的值具有最大索引键长度限制。 有关详细信息, SeeMaximum Index Key Length。 点符号 MongoDB使用点符号来访问数组的元素并访问嵌入文档的字段。 Arrays 要通过基于零的索引位置指定或访问数组的元素,请将数组名称与点(.)和从零开始的索引位置连接起来,并用引号引起来: "<array>.<index>" ...
Index keys that are of theBinDatatype are more efficiently stored in the index if: the binary subtype value is in the range of 0-7 or 128-135, and the length of the byte array is: 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, or 32. Use your driver’s BS...
数组操作符(Array Operators) 变量操作符(Variable Operators) 字面量操作符(Literal Operators) 日期操作符(Date Operators) 条件操作符(Conditional Operators) 数据类型操作符(Data Type Operators) 常用表达式操作符 布尔值操作符(Boolean Operators) 操作符 简述 $and 逻辑与操作符,当他的表达式中所有值都是true...
MongoDB数据库是一种 NOSQL 数据库,NOSQL 数据库不是这几年才有的,从数据库的初期发展就以及存在了 NOSQL 数据库。数据库之中支持的 SQL 语句是由 IBM 开发出来的,并且最早就应用在了Oracle数据库,但是 SQL 语句的使用并不麻烦,就是几个简单的单词:SELECT、FROM、WHERE、GROUP BY、HAVING、ORDER BY,...
"hazard pointer maximum array length" : 1, "history store score" : 0, "history store table insert calls" : 8602760, "history store table insert calls that returned restart" : 0, "history store table max on-disk size" : 0, "history store table on-disk size" : 36864, "history store...
var tags = ["nosql","mongodb","document","developer","popular"];var types = ["technology","sociality","travel","novel","literature"];var books=[];for(var i=0;i<50;i++){var typeIdx = Math.floor(Math.random()*types.length);var tagIdx = Math.floor(Math.random()*tags.length...
schema.maxVarcharLength 整型 --maxVarcharLength 数据采样选项 schema: sample: size: <integer> prejoin: <boolean> namespaces: <array of strings> uuidSubtype3Encoding: <[old|csharp|java]> stored: mode: <[custom|auto]> source: <string> name: <db-name> refreshIntervalSecs: <integer> 名称 类...
ObjectIds are small, likely unique, fast to generate, and ordered. ObjectId values are 12 bytes in length, consisting of: A 4-byte timestamp, representing the ObjectId's creation, measured in seconds since the Unix epoch. A 5-byte random value generated once per process. This random value...
既然可以当做数组处理,那么就可以获得它的长度:cursor.length();或者cursor.count(); 那样我们也可以用循环显示数据 for (var i = 0, len = c.length(); i < len; i++) printjson(c[i]); 7、将find游标转换成数组 > var arr = db.users.find().toArray(); ...