Tag：partition
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Time：2021-5-8
background If you need to regularly clean up the historical data in an ordinary large table. You can use one or more delete statements with a where condition (where condition is time). If the amount of table data is large, it will cause great pressure on the database. Even if we delete the old data, […]
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Time：2021-5-7
preface Flink is a streaming, real-time computing engine The above sentence has two concepts, one is streaming, the other is real-time. Streaming: the data flow in continuously, that is, the data has no boundary, but when we calculate it, we must do it within a boundary range, so there is a problem, how to determine […]
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Time：2021-5-3
The principle is very important. It’s impossible to ask you the order during the interview. It’s all about the principle. If you understand the principle online, you can quickly locate it if you have problems with Kafka, instead of covering your face. We have to understand the principle. If we don’t talk about the principle, […]
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Time：2021-5-2
I suggest you read the previous one first（2） Kafka’s cluster architecture principleIt can help us to have a clearer understanding of Kafka’s face and avoid looking at the leopard from the inside.Today, we will analyze Kafka’s core module producer. Process overview of Kafka producers 1. Kafka producers encapsulate messages into aProducerRecordSend a message to a […]
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Time：2021-4-29
Hadoop and spark are the mainstream big data frameworks at present, but with the advantages of spark in speed and ease of use, some domestic and foreign experts gradually praise spark technology, and think that spark is the future of big data. This paper will analyze the development process of Hadoop ecology and the technical […]
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Time：2021-4-27
Talk is easy, show me the code public class KafkaProducerDemo { public static void main(String[] args) { KafkaProducer<String,String> producer = createProducer(); //Specify topic, key and value ProducerRecord<String,String> record = new ProducerRecord<>(“test1″,”newkey1″,”newvalue1”); //Asynchronous sending producer.send(record); producer.close(); System. Out. Println (“send complete”); } public static KafkaProducer<String,String> createProducer() { Properties props = new Properties(); //Bootstrap.servers must be set […]
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Time：2021-4-26
Consumers and consumer groups 1. A consumerConsume data from a topic: 2. Consumer groups: When the producer’s speed of writing messages to topic exceeds the processing speed of existing consumers, it is necessary to scale consumers horizontally and use multiple consumers to read messages from the same topic to split the messages.The same partition cannot […]
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Time：2021-4-23
Installation of SQLite depends on react native SQLite storage version 0.60 or above, without manual operationyarn add react-native-sqlite-storage AndroidManifest.xml Add storage read permission to<uses-permission android:name=”android.permission.READ_EXTERNAL_STORAGE” /> <uses-permission android:name=”android.permission.WRITE_EXTERNAL_STORAGE” /> Using react native permissions Android API to apply for mobile storage access Use DB to open the database. If the database is opened successfully, the database […]
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Time：2021-4-23
Hadoop and spark are the mainstream big data frameworks at present, but with the advantages of spark in speed and ease of use, some domestic and foreign experts gradually praise spark technology, and think that spark is the future of big data. This paper will analyze the development process of Hadoop ecology and the technical […]
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Time：2021-4-22
Travel around Linux operating system (series articles) Study time: 2021.02.06 – 2021.02.11Video address:open After 12 o’clock, I wish you a good year of the ox and hope your wishes will come true. I planned to finish studying Linux in three days, but I got it on New Year’s Eve. Why did you suddenly learn Linux? […]
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Time：2021-4-21
The name of the window function is over () Function. There are two commonly used properties, partition by and order by. Partition by is similar to group by. We usually call group by grouping and partition by partition. The general structure is as follows: Function(arg1 , arg2 ……) over(partition by clause order by clause windowing […]
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Time：2021-4-20
Today I’ll talk about how some rank functions use window functions. RANK() OVER ( query_partition_clause ORDER_BY clause) DENSE_RANK( ) OVER ( query_partition_clause ORDER_BY clause ) Example hold scott.emp The table is partitioned according to “deptno”, and then ranked according to “Sal” in the partition. Let’s look at rank first. SQL> conn scott/triger; It’s going to […]
