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problem analysis StarRocks BE 5 nodes suddenly dropped within a few minutes. Find BE Out log, the output is as follows:tcmalloc: large alloc 1811947520 bytes == 0x77f9f0000 @ 0x384f94f 0x39ce2dc 0x399646a terminate called after throwing an instance of 'std::bad_alloc' what(): std::bad_alloc *** Aborted at 1641348199 (unix time) try "date -d ...

1. Sort by single field Ascending order: order by ASC (default) Descending order: ORDER BY DESC Query results are returned in the specified order. When actually extracting data or generating reports, they are generally viewed in a certain order. For example, you want to view the information of employees employed by the company. SELECT emp ...

brief introduction Mybatis mate is an mp enterprise level module. It supports sub database and sub table, data audit, data sensitive word filtering (AC algorithm), field encryption, dictionary writeback (data binding), data permissions, automatic generation of table structure, SQL maintenance, etc. It aims to process data more quickly and grac ...

mybatis-config.xml system core configuration file The MyBatis configuration file contains settings and attribute information that deeply affect MyBatis behavior. The top-level structure of the configuration document is as follows: configurationpropertiessettingstypeAliasestypeHandlersobjectFactory (object factory)pluginsenvironments En ...

The original content of GreatSQL community cannot be used without authorization. Please contact Xiaobian and indicate the source for reprint.1. Experimental environment2. Software download3. Start test4. Attached parameter descriptionIn case of accidental deletion or update of data in production, the traditional recovery method is to use backup ...

1, Database cognition (1) What is a database Database: 1) A warehouse that organizes, stores, and manages data according to data structures 2) A container that holds organized data 3) A special file used to store data (2) Type of database Commercial databases: Oracle, SQL Server, DB2, etcOpen source databases: MySQL, PostgreSQL, etcDesktop ...

1, Example 1. Alias For a parameter, it is not necessary to declare an alias, but if the parameter involves null judgment such as if test, it is necessary to declare an alias, otherwise an error will occur dao Map<String,Object> getBidResult(String projectId); String getDicName(@Param("dicCode") String dicCode1); mapper.xml <sele ...

Problem solving ideas I'm used to adding admin after the url to see if it manages the background. Once you see it, you don't need the directory scanning tool Fill in the correct verification code, capture and input ', and check whether there is any error It is found that an error is reported and there is an error injection. Read the error des ...

MergeTree¶ Family (LSM tree data structure) Replicated + MergeTree = replicated MergeTree MergeTree : Replaceingmergetree: de duplication of data with the same sort key during background data consolidation. SummingMergeTree: when merging data, records with the same primary key will be merged into one record. According to the aggregation fi ...

Introduction to SQL SQL(Structured Query Language) is a set of relational database management system (RDBMS) for management, which is based on ANSI (American National Standards) Institute (American National Organization for Standardization) standard computer language, the more important version is SQL92In addition to supporting standard SQL, a ...