• Elasticsearch integrates springboot


    Official documents 1. Find native dependencies <dependency> <groupId>org.elasticsearch.client</groupId> <artifactId>elasticsearch-rest-high-level-client</artifactId> <version>7.9.2</version> </dependency> 2. Find object 3. Analyze the methods in this class Configure basic items Problem: make sure that the dependencies we import are consistent with those we use Related source code Specific API testing 1. Create index2. Determine whether the index exists3. Delete index4. Create […]

  • Meaning and difference between MySQL row lock and table lock


    It is impossible that every day is a good day. When there are bad days, the good days will shine. 1、 Foreword The meaning difference between row lock and table lock should appear frequently in the interview. We should have a systematic understanding of the lock in MySQL. We need to consult the data in […]

  • Five simple steps to master tensorflow tensor


    Author | Orhan g. YAL ç ı nCompile VKSource: towards Data Science If you are reading this article, I believe we have similar interests and will engage in similar industries now / in the future. In this article, we will delve into the details of tensorflow tensor. We will cover all topics related to tensorflow’s […]

  • Differences between exists and in in SQL statements


    select * from A where id in(select id from B) Conclusion: in () is suitable for the situation that the data in table B is smaller than that in table a select a.* from A a where exists(select 1 from B b where a.id=b.id) Exists is used to check whether a subquery will return at […]

  • MySQL explain application details (hematemesis finishing)


    What is explain Using the optimizer can simulate the optimizer to execute SQL query statements, so as to know how MySQL handles your SQL statements, and analyze the performance bottlenecks of your query statements and table structures. What can explain do Sequential reading of tables Which indexes can be used Operation type of data read […]

  • The cache design is good, and the service will not fail


    This article is modified from the live broadcast content of go zero in the fourth issue of “go open source theory”. The video content is long and divided into two parts. The content of this article has been deleted and reconstructed. Hello, I’m glad to come to “go open source theory” to share with you […]

  • SPL data structure 3-splfixedarray


    Splfixedarray is a fixed length array provided in PHP. The array in PHP language is particularly powerful. It can realize data structures such as stack, queue, list, dictionary and so on. Its bottom layer is based on hash table. The array represented by splfixedarray is close to the array in C go and other languages. […]

  • Key points of database interview: about ten million level data query and storage of MySQL database


    abstract: the core of million level and ten million level data processing lies in the design of data storage scheme. Whether the design of storage scheme is reasonable directly affects the operation of data crud. The overall design can consider the following aspects: data storage structure design; Index design; Data primary key design; Query scheme […]

  • MySQL “passive” performance optimization summary!


    When you are young, you don’t know the pain of optimization. When you meet a pit, you know the difficulty of optimization—— Uncle Wang at the entrance of the village The content map of this paper is as follows: I have talked about performance optimization in many previous articles, such as the following: The performance […]

  • [Dachang interview issue 04] how to execute a MySQL UPDATE statement?


    This article has included the 1.1K Star open source learning guide – “big factory interview North”. If you want to know more about the content of the interview and get the offline version of PDF, please scan the code below to pay attention to the official account of “big factory interview”. Thank you! The project […]

  • [Java from entering the pit to giving up] No 6. Tricks of array operation


    preface We have talked about the eight basic data types in Java. This article mainly talks about arrays in reference types. The main contents are as follows: Array introduction ergodic sort common method Array introduction An array is actually a collection of elements of the same data type arranged in a certain order. That is, […]

  • MySQL implicit conversion problem


    The field type ischar, for queryint, such a problem will arise float decimalType is not affected by this Function calculation of index field will lead to index invalidation Integer type values are used for integer or string types String type values are used for shaping, which will lead to index invalidation and full table scanning […]