Programmer Think

Refer to official documents: http://www.mongoing.com/docs/tutorial/remove-shards-from-cluster.html'>http://www.mongoing.com/docs/tutorial/remove-shards-from-cluster.html 1. Check whether balancer is on mongos> sh.getBalancerState() true 2. Find fragment id to delete mongos> sh.status() --- Sharding Status --- s ...

New tablespaces and corresponding users in Oracle Database Create tablespace and temporary tablespace data files Create a tablespace data file SQL> CREATE TABLESPACE rec_news LOGGING DATAFILE '/home/oracle/OracleDB/user/rec_news/rec_news.dbf' SIZE 100M AUTOEXTEND ON NEXT 100M MAXSIZE 5120M EXTENT MANAGEMENT LOCAL; Ta ...

Author: Lei Xia The test team leader of akerson focuses on MySQL related test work. ​ Source: original contribution *Aikesheng is produced by the open source community. The original content cannot be used without authorization. Please contact the editor for reprint and indicate the source. What is Mysql Test? Mysql Test is an integrated al ...

Problem phenomenon Business level The power of the computer room is cut off abnormally, and the access of the business system is slow after the database is restored. Database level Check the instance and find that only one instance is open and the other instance is not started. RAC cluster level View CR ...

Parallel replication records updated from the library do not exist, but exist background The semi synchronous slave database SQL thread with parallel replication enabled reports 1032 errors, while the asynchronous slave database does not report any errors. This happens occasionally Analysis Version mysql 5.7.16 mysql> show variables like '%s ...

Consistent read Consistent read refers to that InnoDB uses multiple versions to query the snapshot of the database at a certain point in time. This query can see the changes made by the transactions submitted before this time point and will not be affected by the later changes or uncommitted transactions. However, this rule do ...

Reprinted from: https://www.jianshu.com/p/124a2e4e8c42 Preface Upgrading the database is a very tedious and seemingly troublesome thing. In an interview, the interviewer asked about adding fields to update the database and upgrading it. I replied that I could make a database migration copyEvery time I judge the updat ...

Summary Current IoT The studio service development module provides the calling module of face recognition API in the cloud market, but there is no direct way to call the Alibaba cloud face recognition API. In this paper, the image is uploaded to the oss service from the device side, and then the image URL is passed through the uplink message, a ...

Sending e-mail should be one of the essential extensions to the website, such as registering for verification, forgetting your password, or sending marketing information to users. 1. Mail Agreement In the process of sending and receiving mail, related agreements need to be complied with, including: Protocol for sending e-mail: SMTP; Protocol f ...

Configured with springboot @EnableTransactionManagement @Transactional But things don't work at all. First, the first point: Spring's AOP transaction management is rollback for runtimeException by default, which is unchecked exceptions. unchecked exception exceptions are subclasses of runtimeException. Do not roll back if you encounter check ...