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1, Global command 1. Query key Keys * query all keys and traverse all key values, complexity O(n) 2. Total number of keys dbsize queries the total number of keys and directly obtains the total number of keys variable built in redis. The complexity is O(1) 3. Check whether the key exists exists key returns 1 if it exists and 0 if it does n ...

Record in detail the detailed process of installing postgres data in the Docker environment under macOS, and record the installation steps and problems. postgres installation First, use the command to pull the image of postgres $ docker pull postgers Using default tag: latest latest: Pulling from library/postgres 5eb5b503b376: Pull compl ...

[tcallusdb knowledge base] restfulapi2 0 for generic table - [Pb] indexquery2 0 Introductionbrief introductionQuery records through the global index and support SQL syntax, as shown in the appendix. To use this interface, you need to add global index fields to the table on Tencent cloud console or local Docker Web platform in advance.POST http: ...

1, NoSQL 1.1 overview Relational database: a database created based on a relational model. The so-called relationship model is "one to one, one to many, many to many". NoSQL = Not Only SQL, meaning: not just SQL; Generally refers to non relational database. Non relational database: A column of data is stored in the model. The rela ...

Redis data type Redis supports five data types: string, hash, list, set and Zset. String (string) As like as two peas, string is the most basic type of redis. You can understand it as a type that is exactly the same as Memcached, and a key corresponds to a value. The string type is binary safe. This means that the redis string can con ...

database Basic concepts of database It is more convenient to manage the data in developmentPreviously, data was managed through IO flow Use the character stream to read one line of data at a timeEncapsulate the read data as an objectAdd multiple objects to the collectionTraverse the collection to determine whether the object is the object ...

1. mysql master image configuration   first, we need to obtain the dockerfile file from the docker hub official website for subsequent modifications. The address is as follows:   https://github.com/docker-library/mysql.git    then copy one copy of the 8.0 folder and name the other 8.0_slave. Enter the 8.0 folder, where ther ...

ArangoDB test Test environment: x-node cluster, xCpu, xg memory start-up Single node startup mode: systemctl arangodb3 start –database.directory = /var/lib/arangodb3 Cluster startup mode: # Start Master arangodb --starter.data-dir=/root/arangodb/db1 --server.storage-engine=rocksdb start # Start other nodes arangodb --starter.data-di ...

[tcallusdb knowledge base] restfulapi2 0 for generic table - [Pb] indexquery2 0 Introductionbrief introductionQuery records through the global index and support SQL syntax, as shown in the appendix. To use this interface, you need to add global index fields to the table on Tencent cloud console or local Docker Web platform in advance.POST http: ...

1. Classification of sub query 1.1. Non associated subquery Subquery statements can be executed separately without reference to any content in the included statement. It is called non associated subquery. 1.1.1. Single row single column subquery The subquery statement returns a single row and single column table. This type of subque ...