Tag:Big watch

  • Circular deletion of large table data (delete data before specified date and condition)

    Time:2021-9-27

    Circular deletion of large table data (delete data before specified date and condition) DECLARE HOWMANY_10MINS NUMBER; –Specify a time node to filter data before deleting the time. –Please pay attention to the delete condition filter in loop, otherwise all items will be deleted!!! SPECIFY_TIME DATE := TO_DATE(‘2021/07/30 23:59:59′,’yyyy/MM/dd hh24:mi:ss’); BEGIN_TIME DATE; END_TIME DATE; BEGIN SELECT […]

  • Application of dataX in data migration

    Time:2021-9-18

    Introduction: application of dataX in data migration DataX definition =========== First, briefly introduce what dataX is.DataX is an offline data synchronization tool / platform widely used in Alibaba group. It realizes efficient data synchronization between various heterogeneous data sources, including mysql, Oracle, sqlserver, postgre, HDFS, hive, ads, HBase, tablestore (OTS), maxcompute (ODPs), DRDS, etc. DataX […]

  • Technology sharing | the fastest logical backup tool in MySQL history

    Time:2021-9-1

    Author: Hong binThe person in charge of aikesheng south district and technical service director, MySQL ace, is good at database architecture planning, fault diagnosis, performance optimization analysis, has rich practical experience, helps customers in various industries solve MySQL technical problems, and provides overall MySQL solutions for customers in finance, operators, Internet and other industries.Source: reproduced […]

  • How to identify bad SQL in gaussdb for DWS

    Time:2021-6-21

    Abstract:Do you know the bad smell in SQL? SQL language is the standard language of relational database (RDB). Its function is to translate the user’s intention into a language that the database can understand. When human beings communicate with each other, different expressions of the same meaning will produce different effects. Similarly, when human communicate […]

  • ETL engineers must see! Super practical task optimization and breakpoint execution scheme

    Time:2021-6-6

    preface With the rapid development of the era of big data, enterprises need to store, calculate and analyze trillions of data every day, while ensuring the timeliness, accuracy and integrity of the analyzed data. In the face of such a huge data system, how ETL Engineers (data analysts) can efficiently and accurately calculate and use […]

  • Performance tuning of gaussdb (DWS) (2): bad taste SQL recognition

    Time:2021-5-7

    abstract: we call the “bad smell” in SQL the SQL statements that lead to inefficient execution and their execution methods. What is the bad taste in SQL SQL language is the standard language of relational database (RDB). Its function is to translate the user’s intention into a language that the database can understand. When human […]

  • MySQL 8.0 big table seconds plus field, is it true?

    Time:2021-2-17

    preface:  I’ve heard for a long time that MySQL 8.0 supports fast adding columns, which can add fields in seconds for large tables. The author also has 8.0 environment, but has not been tested. In this article, let’s take a look at how to quickly add columns to MySQL 8.0. 1. Understand the background information […]

  • Big data interview questions collection_ Hive correlation

    Time:2020-11-7

    1. Group by / distinct / row_ Number / custom function2.row_number rank dense_rank3. How to customize and use hive UDF function4. Hive optimization (1) Consider optimization from table design 1. Reasonable use of intermediate result set can reduce the IO load of Hadoop; 2. Reasonably design table partition, including static partition and dynamic partition; 3. […]

  • How to quickly delete data from large SQL Server tables

    Time:2020-10-14

      In SQL server, how to quickly delete data in large tables?  Before answering this question, we must make clear the context and the actual, specific needs, different scenarios have different response methods.     1: Delete all data in the whole table     If the data of the whole table is cleared and […]

  • In and exists in Oracle

    Time:2020-10-4

      In is a hash connection between the outer table and the inner table, while exists is a loop loop loop for the outer table. Each loop loop will query the inner table. It has always been considered that exists is more efficient than in. If the two tables queried are of the same size, […]

  • [pl / SQL] difference between rebuild index and rebuild Index Online

    Time:2020-8-4

    After reading this chapter, you will learn the following: What’s the difference? What should I pay attention to when rebuilding indexes for large tables? difference:1. When rebuilding, the original index is usually updatedINDEX FAST FULL SCAN。2. When rebuild online, it is executed without the original indexTABLE ACCESS FULL3. Sort will occur in both rebuild and […]