manual reference

Environment Introduction192.168.1.151 Fedoraserver as the primary library for the replica set, there are already data192.168.1.152 Fedoraserver from library, empty instance192.168.1.153 Fedoraserver from library, empty instanceMongoDB replica set

1.profile profiling levels: 0, close profile,1, crawl only slow query,2, fetch all data. start profile and set the profile level:       can be mongo shell can also be started by the profile command in the driver, and the record will be saved

Some records recorded by date in development require statistics in various dimensions, such as day, month, year, and hour ,.. For Grouping statistics, some fields need to be de-duplicated. In the previous [Mongo] grouping statistics by time (group

One, garbage collection mechanism (GC garbage collection):1. The memory used by a system-level thread is automatically checked for the release of useless objects.2, garbage collection mechanism has multiple different algorithms to implement garbage

First, the block's retain cycle compilation warning only appears in the ARC project. A solution here: http://blog.csdn.net/itianyi/article/details/8715857 I personally don't feel very good, so I checked the apple documentation and described it as

After os5.0, you can use arc (automatic reference counting: automatic reference count) to replace the previous MRC (manual reference counting: manual reference count ). Using Arc reduces the trouble of code and forgetting to release objects. But

Jesting:iOS development has come to an arc era, generally do not need us to pay too much attention to how the memory is allocated, how to manage. For a long time, I do not know what memory management is a ghost, but if you encounter this problem,

Because MongoDB is non-relational (join), references between documents ("Foreign keys") are usually solved by the client through additional queries to the server (linking ). These connections are always resolved on the client. It is very easy to do

NotesHide details in this Guide This style guide contains a lot of initial invisible details. They are marked as triangle icons, which you can see on the left. Click it now and you will see "Long live" below. BackgroundObjective-C is a dynamic and

iOS5.0 can start with arc (Automatic Reference counting: Auto reference count) instead of the previous MRC (Manual Reference Counting: Manual reference count). Using arc will reduce the amount of code and the frustration of forgetting to release

Introduction Memory Management: Clean up (recycle) unused memory so that memory can be reused.This is a concern-how to determine that an object is no longer needed and that the memory it occupies can be recalled.Prior to the release of Xcode4.2,

In the 2011 WWDC, Apple mentioned that 90% of the crash were caused by memory management, and ARC ( Automatic Reference Counting ) was the solution given by Apple. With ARC enabled, developers do not need to worry about memory management, and the

Management scope: Any object that inherits NSObject, basic data types are not managedEssential reason: Because the object and the basic data type in the system storage space is not the same, the local variable is mainly stored in the stack, and the

iOS5.0 can start with arc (Automatic Reference counting: Auto reference count) instead of the previous MRC (Manual Reference Counting: Manual reference count). Using arc will reduce the amount of code and the frustration of forgetting to release

Analysis of global and $globals[in the PHP language PHP in the global and $globals not only the wording is not the same, 2 of the difference is still very large, in practical applications need to pay attention to! Let's look at the following

Environment: Viretualbox Redhat7.0 mongoDb3.6 Steps: 1. Install Virtual machine: Please check the Linux installation Reahat Basic is the next step 2. Install MongoDB Need tool Xshell If you don't please contact me to send you MongoDB's tar package

Automatic Reference Counting (ARC), an automatic reference count, is a compile-level feature of the development of a cocoa program for automatic memory management. 1: In Xcode 4.2, use a template to create a new project that will use the "Default"

Enumerate common commands for MongoDB monitoring1. Monitoring statisticsMongostat can be used to view the current qps/memory usage/connection number, as well as the pressure distribution of multiple ShardCommand Reference./mongostat --port 27071 -u

BackgroundMONGODB provides SQL-like data query and operation methods, but also includes aggregation operations, indexes and other mechanisms;In previous experience, improper library table operations or indexing patterns often cause problems such as

A talk about MongoDB (i.)When you start to learn MongoDB, look for some Chinese blogs. Later found that a lot of knowledge can not be searched, the last is to see the official website and the authoritative guide, or the two reliable, free time to