pros and cons of mongodb

Types and pros and cons of MySQL indexesAn index is a special kind of file (an index on a InnoDB data table is an integral part of a table space), and they contain reference pointers to all records in the datasheet.Note: [1] The index is not omnipotent! Indexing can speed up data retrieval operations, but it slows down data modification operations. Each time a data record is modified, the index must be refr

other. This allows multiple processes to access the same physical memory page directly. Like accessing your own private space (but in essence not private but shared). Therefore, this inter-process communication method is the quickest way to realize communication among the processes in the same computer system. And its limitations lie in this. Processes that share memory must coexist with the same computer system. There is physical memory that can be shared before the line.Three ways to characte

the user can already see the interface. Can be very good to prevent the interface is too complex to cause the black screen time is too long, but this is only a way to improve the user experience, to root or optimize the interface. The data is then asynchronously loaded. Finally, there is a handler used by the small strategy, when the data is more than the time can be appropriate to delay the handler send, for example, can call handler.sendemptymessagedelayed, set a delay time.Six, the network a

and Localstoragesessionstorage is used to store data locally in a session, which can only be accessed by a page in the same session and destroyed when the session ends. So sessionstorage is not a persistent local store, only session-level storage.While Localstorage is used for persistent local storage, data is never available until the data is actively deleted. The concept of Web storage is similar to a cookie, except that it is designed for larger capacity storage. Cookie size is limited

different locations. Amerivault is also an online backup service provider that helps users save backup data for users in three locations, each with two different disk systems, and a third backup in a business continuity site that is 1000 kilometres away. The online backup provider DS3 uses emcclariion as the primary storage device, and in order to make the backup easy, they keep the backed up data in other high-end disk systems, and in DS3 's three datacenters, there is a data center dedicated

framework does just fine. For a front-end project, the button section can define a BTN class as a button initialization (A or button, input initialization, fillet, border, cursor, and so on), and then define classes such as Btn-blue, btn-red to refine the style of the button. Then for all the buttons for the whole project, you can implement the style with just two additional classes.============= below is an informal usage of my own ================Another application scenario is to replace the

Factory mode is a design pattern of creation, it accepts the instruction, creates the instance which conforms to the requirement, it mainly solves the unified distribution of the resources, the creation of the object is completely independent, so that the object creation and the specific use of the customer is irrelevant. Main application in multi-database selection, class library file loading and so on.　　　The strategy mode is to solve the policy switching and extension, more concise is to defi

Microsoft TFS:Advantages:The Mission edition is a great place to take your needs and project progress, and it's more useful for small teams than Gantt charts.can be seamlessly engaged with VSDisadvantages: tfs the cost of personal consumption is relatively larger. tfs through complex seemingly powerful configuration management, the online as the entire project cycle of the normal, which in actual use caused great inconvenience. The whole system is implemented with ASP, and the browser accesses

server, maintain a set of basic data, the client does not need to install, through the browser can be used;L Okit allows leaders to get the information they want when they need to focus on a project, and no longer requires project managers to spend a lot of time organizing reports and sending emails.L Okit can be deployed to the Internet so that project teams can be distributed anywhere and can work together as long as they can connect to the network.1 servers, 5 minutes, set up a management en

, Git is suitable for simple software projects, typically some open source projects, such as the Linux kernel, busybox, etc.Instead, SVN excels at multi-project management.For example, you can store a bsp/design document/File system/application/Automation compilation script for a mobile project in an SVN repository, or a file system that stores 5 mobile projects in one SVN.The n (number of items) * m (Number of components) warehouse must be established in Git. Only a maximum of n or M will be re

of network services, then the single-point nginx can not be satisfied, when the use of LVS or commercial array is the first choice, nginx at this time as a LVS or array of nodes to use, The specific LVS or array is selected according to the size of the company and the budget to choose, the application delivery function of the array is very powerful, I used in a project, cost-effective is much higher than F5, commercial first choice! But in general this phase of the relevant talent to keep up wi

1. The advantages and disadvantages of Visual Source safe:Advantages: If the development tool is vs.net, with VSS more suitable, convenient, installation configuration and use are simple, version control is simple, after playing the label, to restore to this version is simplerDisadvantage: The base LAN, low efficiency, VSS itself is poor security, only support widows platform2. Concurrent Version System Advantages and disadvantages:Advantages: Once become the mainstream, do not worry about data

core function is very few, does not install the plug-in basically cannot use.BUGZILLA :Advantages:1, Bugzilla no charge,2, Bugzilla now has Chinese version supportDisadvantages:1, Bugzilla can only manage defectsApple XCode :Advantages:1, you can automatically create a classification chart.2. Automatically provides undo, redo, and save functions without writing any coding.Disadvantages:1, after the update version, a plugin may become invalid.What are the current popular source program version m

expansion of network services, then the single-point nginx can not be satisfied, when the use of LVS or commercial array is the first choice, nginx at this time as a LVS or array of nodes to use, The specific LVS or array is selected according to the size of the company and the budget to choose,the application delivery function of the array is very powerful, I used in a project, cost-effective is much higher than F5, commercial first choice! but in general this phase of the relevant talent to k

choice, at this time these things get started fast, easy to configure, on the seven layer above the use of HTTP protocol can. This is the first choice.The second stage: with the further expansion of network services, then the single-point nginx can not be satisfied, when the use of LVS or commercial array is the first choice, nginx at this time as a LVS or array of nodes to use, The specific LVS or array is selected according to the size of the company and the budget to choose,the application d

file access A) consumes Namenode of memory b) Seek time exceeds read time 3. Concurrent write, File random modification A) A file can only have one writer b) only support append HDFs processing of a large number of small files: compression of small files, that is, 10,000 small files in HDFs only as a file for storage, compression processing.

Singlemode Fiber: Single mode optical fiber can only transmit in a given working wavelength.Advantages: The transmission bandwidth of single mode fiber is wide and the transmission capacity is large. Optical signal can be transmitted along the axial direction of light, so the loss of light signal is very small, discrete is also very small, single-mode fiber backbone cabling The maximum distance of 3000m.Cons: High prices.Multimode fiber: multimode fiber optical signal more than one wavelength (m

It is not the IT entrepreneurial advantage of it people:1) More respect for market-oriented rather than technical2) More attention to product details rather than technology3) more focused on enterprise balance rather than technologyIt is not the IT entrepreneurial disadvantage of it people:1) Abandonment of technical planning due to marketing2) Loss of technical agility due to demand3) The technology gene is erased because of balance It is not the IT business of it entrepreneurial

Comparative analysis of the pros and cons of mainstream PHP frameworks, comparative analysis of framework advantages and disadvantages PHP is a popular open source server-side scripting development language both at home and abroad. Able to adapt to the development needs of large and medium-sized projects. In this article we will introduce several mainstream PHP framework and its related advantages and disa

width and spacing.. ALLEGRO has a stroke function, with skill added functionality.. Allegro is more convenient for multi-person collaboration.What are the hazards of the main components of the substrate (FR4) and PP plates and the Chinglei rays?Commonly used FR-4 and P.P. Board, the main ingredient is epoxy resin and glass fiber . The harm you refer to, should only be the Chinglei after the shooting process will produce harmful substances. In the laser processing after the main material is carb