cache penetrationCache penetration means that the data requested by the client does not exist in the cache and the database, so the cache will never take effect, and these requests will hit the databaseIf a malicious user uses countless threads to concurrently access non-existent data, these requests will all reach the database, which is likely ...
Posted by bliss322 on Sun, 25 Sep 2022 21:01:59 +0300
Redis advanced practice
Comparison between redis and mysql redis slow log queryredis high availability and cluster
redis master-slave replication
Synchronization mechanism**Master slave replication principle****Command propagation**SYNC and PSYNCConsistency of redis replication ...
Posted by ben2.0 on Sat, 27 Aug 2022 14:01:57 +0300
Intersection: an element that appears at least twice in all setsUnion: combine the elements of multiple sets and remove the duplicate elementsDifference set: an element that exists in the first set and does not exist in other sets
commandexplainsinter key [key ...]Gets the intersection of all setssinterstore desiti ...
Posted by KoopaTroopa on Sun, 22 May 2022 02:45:39 +0300
1. MyBatis first level cache
The first-level cache is at the SqlSession level. The data queried through the same SqlSession will be cached. The next time the same data is queried, it will be obtained directly from the cache and will not be re-accessed from the database.Four situations that invalidate the L1 cache:
Different SqlSession s ...
1, Preparatory work
The redis compressed package of 5.0.4 can be downloaded from the official website. linux environment
2, Unzip and install
1. Create 6 new folders to install redis directory The directory path is / root/tools/7001
[root@my 7001]# pwd
[root@my 7001]# ls
2. Unzip and install redis
Posted by sarijit on Thu, 19 May 2022 00:34:17 +0300
On DE2 development board, use serial port to receive 640 * 480 color pictures sent by Qt program on PC, store them in SDRAM in RGB565 format, and display them on the screen through VGA. Development board: DE2 Development tool: Quartus II 13.0 + Modelsim 10.5 SE Global clock: 50M VGA clock: 25M SDRAM clock: 100M
overall stru ...
Posted by chopper_pc on Fri, 13 May 2022 04:35:13 +0300
Chapter V complete collection of cache é variables $HALT variables
Contains the pause trap routine call.
$HALT contains the name of the current pause trap routine. When the HALT command is encountered, the application will call the pause trap routine. The pause trap routine can perform cleanup or ...
Posted by El Ornitorrico on Thu, 28 Apr 2022 08:23:26 +0300
1. Red envelope ranking query
In the above case, we realized the information query of a user grabbing the red envelope. Next, we realized the publicity of grabbing the red envelope and sorted it according to the amount of the red envelope For the information of 100 users, the concurrency of this data will be greater, and we need to cache ...
Posted by lovasco on Fri, 22 Apr 2022 15:20:21 +0300
Catalog Spring Cloud Alibaba microservice series articles
0. Spring Cloud Alibaba micro service series - preparations1. Spring Cloud Alibaba micro service series - service registry Nacos2. Spring Cloud Alibaba micro service series - configuration center Nacos3. Spring Cloud Alibaba micro service series ...
Posted by Integra_grrl on Sun, 17 Apr 2022 06:10:23 +0300
Chapter 43 cache é variable Daquan $ZTIMEZONE variable
Contains the time zone offset of the Greenwich meridian.
$ZTIMEZONE can be used in two ways:
Returns the local time zone offset of the computer.Sets the local time zone offset for the current process.
$ZTIMEZONE contains the time z ...
Posted by umbra on Sun, 17 Apr 2022 01:52:15 +0300