centos7 quick guide for building MySQL NDB Cluster 7.5/7.6 cluster
NDB Cluster is a technology that enables in memory database clustering in a shareless system. Shareless architecture enables the system to use very cheap hardware with minimal specific requirements for hardware or software.
NDB Cluster is designed without any single point of failure. In a non shared system, each component should have its own m ...
Posted by DrTom on Sun, 22 May 2022 08:32:09 +0300
Java topic Database connection pool, manually create connection pool+dbcp+C3P0+Druid+dbUtil
connection pool
(database connection pool)
Closing the link every time you link to the database is rather cumbersome and wastes time and resources. Now we can get the database link through the connection pool, and put it back after use up, which can save the time and operation of constantly creating and closing the connection, which is more eff ...
Posted by beckjo1 on Sun, 22 May 2022 06:26:33 +0300
Redis intersection union difference set
introduce
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
Related commands
commandexplainsinter key [key ...]Gets the intersection of all setssinterstore desiti ...
Posted by KoopaTroopa on Sun, 22 May 2022 02:45:39 +0300
Redis data type (hash type)
hash type and operation
① Overview
The hash type in Redis can be understood as a map container with String Key and String Value, so the hash type is suitable for storing value object information. Such as Username, Password or Age. Even if there are only a few fields in the hash, its data only takes up a small amount of disk space. Each ha ...
Posted by daniel_grant on Sat, 21 May 2022 04:01:06 +0300
Detailed process of Dameng mpp + active and standby
1. Refer to DM for software installation steps_ dw. txt
First node Second node
EP01 (main) EP02 ((main)
EP12 (prepare) EP11 ((standby)
2. Install mpp active / standby
--------------------First node 0.101
(1) Initialize instance EP01 main library:
./dminit PATH=/dm8/dmdata DB_NAME=EP01 INSTANCE_NAME="EP01" PORT_NU ...
Posted by shane07 on Sat, 21 May 2022 02:25:45 +0300
Mysql database 2: DML operation, multi table relationship and query operation
catalogue
1. DML - modify operation
2. DML delete
3. Mysql simple query operation
4. Multi table relationship and table building principle
4. Mysql multi table Association query
4.1 mysql Association query classification
4.2 write sql statement to realize mysql multi table Association query
5. Mysql query operation
1. DM ...
Posted by drag0n on Fri, 20 May 2022 23:14:59 +0300
How does FlinkX read and write to the Clickhouse?
Introduction: This paper will mainly introduce the process and related parameters of reading and writing Clickhouse by FlinkX. The core content will focus on the following three questions: 1 Which version does FlinkX Clickhouse support 2. What are the parameters for Clickhouse to read and write Clickhouse 3. What are the instructions for Clickh ...
Posted by pedroz on Fri, 20 May 2022 16:16:32 +0300
When deleting records logically - ensure the uniqueness of the business
catalogue
Business background
Business background
Generally, some record tables of the business system have some uniqueness constraints. For example, duplicate names are not allowed under the same user; You can usually create a unique index on the specified column, for example:
CREATE TABLE `novel`
(
`id` bigint(20 ...
Posted by JayBachatero on Fri, 20 May 2022 14:36:13 +0300
Pyhton3, database table design and data storage for website construction~
Building your own website is one of the signs of success as a coder,
Then there are other signs of success, holding Bai Fumei in your left hand, rolling a small barbecue in your right hand, and stepping on Santana under your feet
Um
Crawling data
Some children will say, uncle fish, aren't you designing a database table? How do you return the p ...
Posted by kingcobra96 on Fri, 20 May 2022 09:38:56 +0300
Shell script integer value comparison, logic test, if statement
1. Conditional test operation
[conditional expression]
(1) document test[file or directory]-d: Whether the directory is directory (test) -e: Test whether the directory or file exists (Exist) -f: Test whether it is a file -r: Test whether the current user has permission to read, -w: Test whether the current user has permission to write -x: T ...
Posted by Sneo on Fri, 20 May 2022 07:41:43 +0300