Article directory Performance of hive data skew Reasons for hive data skew Hive data skew solution Hive tilt group by aggregation tilt Map and Reduce optimization of Hive tilt When Hive tilt’s HQL contains count(distinct) Hive tilt join optimization in HQL Summary of the above description The underlying processing logic of ODPS MR can be […]
Tag: skew
Data skew and data skew solutions
1. What is data skew The core of Hadoop that can batch process massive amounts of data lies in its distributed idea, that is, multiple servers (nodes) form a cluster to perform distributed Data processing. For example, if I want to process a table with 1 billion data, my cluster consists of 10 nodes. It […]
Spark tuning for big data: data skew
Directory Data skew Data skew is large key positioning Single table data skew optimization Join data skew optimization Broadcast Join Split large keys, break up large tables, and expand small tables. Data skew phenomenon 1. Phenomenon Most tasks run very fast, but there are a few tasks that run extremely slowly. It is possible that […]
Spark data skewing and tuning
1. What situations will cause data skew and solutions? In distributed computing, data skew refers to the unbalanced distribution of data among distributed nodes, causing some nodes to be overloaded, thereby affecting the operating efficiency and performance of the entire task. For Spark, data skew is a common problem, which may lead to long task […]
MapReduce-based Hive data skew scenarios and tuning solutions
Article directory 1 Hive data skew phenomenon 1.1 Scenarios where Hive data is skewed 1.2 Optimization ideas to solve the problem of data skew 2 Methods to solve the problem of Hive data skew 2.1 Enable load balancing 2.2 Introducing randomness 2.3 Using MapJoin or Broadcast Join 2.4 Adjust the data storage format 2.5 Bucket […]
How to solve data skew in Hive
Directory 1) Data skew caused by group aggregation (1) Determine whether the tilted value is null (2) Map-Side aggregation (3) Skew-GroupBy optimization 2) Data skew caused by Join (1) Map Join (2) Skew Join (3) Adjust the SQL statement The problem of data skew usually refers to the uneven distribution of the data involved in […]
[How to solve MapReduce data skew?]
Directory Preface: MapReduce data skew may have the following reasons: In order to solve the problem of MapReduce data skew, some strategies can be adopted, such as: Data preprocessing: Before the MapReduce task, the data is preprocessed to make the data distribution more even. The code for data preprocessing can be further optimized, for example: […]
Hive/spark data skew solution
Hive data skew and solutions 1. What is data skew Data skew is mainly manifested in the fact that when the mapreduce program is executed, most of the reduce nodes are executed, but one or several reduce nodes run very slowly, resulting in a long processing time of the whole program. There are many more […]
Redis data distribution optimization: how to deal with data skew?
Redis core technology and practical notes Author: Jiang Dejun In a slicing cluster, data is distributed to different instances for storage according to certain distribution rules. For example, when using Redis Cluster or Codis, the data will first model the Slot (logical slot) according to the calculated value of the CRC algorithm, and at the […]
Analysis of Redis Cluster Data Skew Problem and Solution
Overview In server-side system service development, caching is a commonly used technology, which can improve the system’s processing efficiency of requests, and redis is a leader in the caching technology stack, widely used in various service systems. In large-scale Internet services, there are massive requests to be processed and cached data to be stored every […]