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The software download link is at the bottom thank: CSDN Daniel: Travel through IT bilibili Daniel: amoscloud2013 1. Preliminary preparation Five 8G virtual machines are CDH1, cdh2, cdh3, CDH4 and cdh5 respectively. JDK is installed on all virtual machines 2. Modify IP and host name Select CentOS 7 for cluster deployment. All three vir ...

Let's take a look at a problem in actual generation: There is a user access record table, which records the user's access under different channels, operating systems and versions, As follows: create table test.test10 as select '10001' as uid,'xiaomi' as qid,'android' as os,'1.2.2' as ver union all select '10002' as uid,'xiaomi' as qid,'andro ...

catalogue 1, SparkSession, DataFrame and Dataset 2, Spark Sql parsing 1. Overall overview 2. sql syntax parsing key objects 3, Spark LogicalPlan 1. Overall overview 2. LogicalPlan class structure system​ 3. Generated by analyzed logicalplan 1, SparkSession, DataFrame and Dataset 1. To use the sparksql function, you need to create a ...

catalogue 1, DDL(Data Definition Language) 1. Create database 2. Query database 3. Modify database 4. Delete database 5. Create table Management table (internal table) External table Conversion between two tables Modify table Delete table Clear table 2, DML data operation 1. Data import Load data into a table (load) Insert data ...

0 - problem description SQL tests whether there is a value in a group of data. You want to generate a Boolean value according to whether a group of row records contain a specific value. Imagine an example where a student will take several exams over a period of time. Suppose he takes three exams every three months. As long as he has pas ...

insert overwrite implementation of Doris partition bucket table (1) Real time project If it is real-time, we should pay attention to timeliness. Directly select the unique key model table and select the non repeatable columns as unique keys A simple example of creating a single partition table CREATE TABLE order_tab ( orderid BIGINT, ...

1. Process control structure 1.1 general In the actual development, we have to write thousands of lines of code. The order of the code is different, and the execution results will certainly be affected. Some codes can be executed only if they meet specific conditions, and some codes need to be executed repeatedly. How to reasonably plan these ...

I. diagram sequence table Concept of sequence table Sequential table is a linear structure in which data elements are stored in sequence with a storage unit with continuous physical addresses. Generally, array storage is used. Complete the addition, deletion, query and modification of data on the array. (what we want to describe below is a dy ...

Redis five data types Redis key basic command set key name -- Set a basic key value pair keys * -- View all keys exists key -- View the corresponding key Does it exist move key Number of corresponding database -- Put this key Move the corresponding data to another database expire key Expiration time(Unit second) -- Set how long this d ...