• C ා complete record of steps for simple operation of mongodb


    preface Mongodb is a high-performance, open-source, modeless non relational database product written by C + +, which is the database with the most abundant functions and the most like relational database. It extends many functions of relational database, such as auxiliary index, range query, sorting, etc. Mongodb mainly solves the problem of access efficiency of […]

  • Aggregation of mongodb tutorials (count, distinct, and group)


    1. count: Copy codeThe code is as follows: — in an empty collection, count returns 0.     > db.test.count()     0— test the return value of count after inserting a document.     > db.test.insert({“test”:1})     > db.test.count()     1     > db.test.insert({“test”:2})     > db.test.count()     2— count, like find, accepts conditions. From the results, […]

  • An example tutorial of aggregate query by day in mongodb


    Preface Recently, when writing a project, we encountered a problem. Mongodb was used to record the execution results of use cases, but the date format was used to record the time. Now there is a requirement to count the successful use cases and the failed use cases every day in days. When it comes to […]

  • Using HyperLogLog Function to Realize Advanced Analysis in Apache Spark


    Pre-aggregation is a common technology in high performance analysis. For example, 10 billion accessed data per hour can be aggregated through common query latitudes and reduced to 10 million accessed statistics, which can reduce the data processing by 1000 times, thus greatly reducing the amount of computation and improving the response speed in query. Higher-level […]

  • Mongodb Aggregation Power Node Java Institute Arrangement


    Today, I would like to share with you some interesting knowledge in mongodb, including aggregation and cursors. One: Polymerization Common aggregation operations are like SQL server: count, distinct, group, mapReduce. <1> count Count is the simplest, easiest, and most commonly used aggregation tool, and it’s almost exactly the same as count in our C#. <2> […]

  • A very useful Aggregate introductory tutorial in mongodb


    Preface Aggregate translates to aggregate, but the experience of using it in practice is very much like the pipeline in linux. After each pipeline is processed, the result is handed over to the next pipeline. Your data is like water flow. Finally, you can get the data you want through each pipeline. What do we […]