Redis cache

The front page is usually a page with a domain name ( Servers or clusters ), In particular, the pressure of visiting the home page is relatively large , Therefore, the front-end advertisements need to use caching to relieve the pressure of database access , Speed up access

Sometimes an error is reported when uploading pictures , Unable to resolve the address of the image server , The reason is that the configuration file is not compiled to target, Therefore, it cannot be resolved in the method Should first clean To compile

And that is $scope.entity.picMeetingnewspaperwrongsaypicnotsetThe\; righteousprimarybecauseJustyeschengorderNoknowAvenueentityyesNoyesOneindividualYeslikeIPeoplecanWithFirstsetThe\; righteous$scope.entity ={} ( It is best to bind stand-alone events to the new buttons in the page ng-click=‘entity={}’)

Use redis The situation of : Frequent visits , Large amount of visits , Less content change , The content is relatively unimportant

How to reduce the pressure of database access :1. Data caching 2. Page static

When caching, you should connect redis,redis There is a configuration file to load , The address of the server , Port number , Timeout time , Maximum number of connections, etc

in addition redis There is one spring The configuration file , It's equipped with a redis object , One redisConnection object One redisTemplate object

redisTemplate operation
Delete a key value pair delete(“ Key name ”)

add to String Type value boundValueOps(“ Key name ”).set(“ Content ”)
obtain String Type value boundValueOps(“ Key name ”).get()

add to set Type value boundSetOps(“ Key name ”).add( Value content )
obtain set Type value boundSetOps(“ Key name ”).members()
Delete one of the values boundSetOps(“ Key name ”).remove(“ value ”)

add to list Type value boundListOps(“ Key name ”).rightPush/leftPush( Value content )
obtain list All values of type boundListOps(“ Key name ”).range( Starting index , The number of data )
Delete one of the values boundListOps(“ Key name ”).remove( Number of deletions ,“ value ”) If the number written is less than 1 Delete at least one , If you write more than one, you can delete several within the deleted quantity
obtain list A value of type boundListOps(“ Key name ”).index( Indexes )

add to hash Type value boundHashOps(“ Key name ”).put(“key1”, value 1)
obtain hash Type value boundHashOps(“ Key name ”).get(“key1”)
Delete one of the values boundHashOps(“ Key name ”).delete(“key1”)
Get all key boundHashOps(“ Key name ”).keys()
Get all values boundHashOps(“ Key name ”).values()

redis Cache emptying problem
The data query should first query the cache , The cache no longer queries the database , But the cached data must be consistent with the database data , Therefore, the corresponding cache should be emptied when adding, deleting or modifying , However, the cache data of all advertisements cannot be cleared when clearing the cache , The type of advertisement that should be emptied should be changed , So there is a big key, Then there are many small key

When adding, deleting, or modifying, the cache is emptied differently

When adding, empty the cache of the added type
When deleting, you can delete this type , However, deleting involves deleting multiple , To avoid duplicate deletion of the same type of cache , You can put the type of deleted advertisement into a set aggregate , Delete after de duplication , Avoid repeated operations

The modification involves the modification of the advertisement type , In this case, you should clear the cache of the type before and after the change , To avoid duplicate deletion, you can judge whether the types are the same

JPA Java Persistence API java Persistence layer API ORM Object Relational Mapping Object relation mapping