Understand the role of the database
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The origin of database management software
Based on what we've learned before , If you want to keep the data forever , It's all in a file , without doubt , A file can only exist on one machine .
If we ignore the efficiency of accessing data directly based on files for the time being , And suppose all the components of the program run on one machine , Then use the file to access the data , No problem .
Unfortunately , All of these assumptions are made by yourself , The above hypothesis has the following problems ......
1、 It's impossible for all the components of a program to run on one machine
Because once this machine fails, it means that the whole software will crash , And the efficiency of the program depends on the hardware that carries it , And the performance of a machine is always limited ,
Limited by the current level of hardware , There are limits to vertical expansion of a machine's performance .
So we can only enhance the overall performance of our system through horizontal expansion , This requires us to distribute the various components of the program to multiple machines to execute .
2、 Data security issues
according to 1 Description of , We distribute the components of the program to each machine , But we need to know that each component is still a whole , Between the lines , The data of all components should be shared .
But the components on each machine can only operate the local files , This leads to data inconsistency .
So we thought of separating data from applications ： Put the files in a machine , Then multiple machines will access the files on this machine through the network （ use socket Realization ）,
That is to share the files on this machine , Sharing means competition , There will be data insecurity , Need to be locked ....
3、 Concurrent
according to 2 Description of , We have to write a socket The server manages this machine （ database server ） File on , And then write a socket client , Complete the following functions ：
1. Remote connection （ Support concurrency ）
2. Open file
3. Reading and writing （ Lock ）
4. Close file
summary ：
Before we write any program , Need to write a good network-based operation on a host file program （socket Server and client programs ）, So someone wrote this kind of program as a
Specialized processing software , This is it. mysql The origin of database management software , but mysql It's not just about data sharing , And query efficiency , Security and so on ,
All in all , Freeing programmers from data management , Focus on writing your own program logic .
