Mongodb Find All Documents

"51CTO exclusive feature" 2010 should be remembered, because the SQL will die in the year. This year's relational database is on the go, and this year developers find that they don't need long, laborious construction columns or tables to store data. 2010 will be the starting year for a document database. Although the momentum has been going on for years, now is the age when more and more extensive document databases appear. From cloud-based Amazon to Google, a number of open-source tools, along with the birth of Couchdb and MongoDB. So what ...

"51CTO classic" I like MongoDB mainly because it is so simple and natural to use it in dynamic languages. So far, I've used it in two projects (Encode and SPARRW), although I'm very happy with the choice, but there are some problems I haven't noticed, and these problems have kept me scratching my scalp for hours. If you have more than one machine, and then allocate a few more machines for the database, then some problems can be solved, but my project is running on a single (virtual) server on the low flow w ...

1.count Count returns the number of documents in the collection &http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;db.refactor.count () No matter how large the collection is, the number of documents can be returned quickly. You can pass the query, MongoDB calculates the number of query results Db.refactor.count ({...).

"51CTO classic" MongoDB and Couchdb are both document-oriented databases that use JSON document formats that are often viewed as NoSQL databases and are now fashionable and have a lot in common, but when it comes to queries, the difference is obvious, COUCHDB requires predefined views (essentially JavaScript mapreduce functions), while MONGODB supports dynamic queries (essentially similar to ad hoc queries on traditional relational databases), and more importantly, when it comes to queries, Co ...

NoSQL Recent momentum is good, http://www.aliyun.com/zixun/aggregation/13461.html ">mongodb is one of the Jiao jiao, oneself learn nosql when also reference a lot of information, The final decision to start from the MongoDB, the most important reason has two: 1 oneself is a simple amateur, all problems I think whether there is a simple way to solve, rather stop to think a lot of time, also do not want to use stupid method to do immediately, and Mong ...

&http://www.aliyun.com/zixun/aggregation/37954.html ">nbsp;1.find MongoDB uses Find to query. The query is to return a subset of the files in the set. The child collection ranges from 0 documents to the entire collection. The first parameter of find determines which documents to return. The form is also a document that describes the details to be queried. The empty query document {} matches the entire contents of the collection. If you don't specify ...

In mailbox rapid expansion process, one of the performance problems is the MongoDB database level write lock, the time spent in the lock waiting process, directly reflects the user's use of the service process delay. To address this long-standing problem, we decided to migrate a common set of MongoDB (storing mail-related data) to a separate cluster. According to our inference, this will reduce the lock latency by 50%, and we can add more fragments, and we expect to be able to optimize and manage different types of data independently. We start from Mon ...

Several years of work down, also used several kinds of database, accurate point is "database management system", relational database, there are nosql. Relational database: 1.MySQL: Open source, high performance, low cost, high reliability (these features tend to make him the preferred database for many companies and projects), for a large scale Web application, we are familiar with such as Wikipedia, Google, and Facebook are the use of MySQL. But the current Oracle takeover of MySQL may give us the prospect of using MySQL for free ...

In the past few years, relational databases have been the only choice for data persistence, and data workers are considering only filtering in these traditional databases, such as SQL Server, Oracle, or MySQL. Even make some default choices, such as using. NET will typically choose SQL Server, and Java may be biased toward Oracle,ruby, Mysql,python is PostgreSQL or MySQL, and so on. The reason is simple: In the past a long time, the relational database is robust ...

It was easy to choose a database two or three years ago. Well-funded companies will choose Oracle databases, and companies that use Microsoft products are usually SQL Server, while budget-less companies will choose MySQL. Now, however, the situation is much different. In the last two or three years, many companies have launched their own Open-source projects to store information. In many cases, these projects discard traditional relational database guidelines. Many people refer to these items as NoSQL, the abbreviation for "not only SQL." Although some NoSQL number ...