Next, I will talk about the advanced types of TS. The so-called advanced types refer to some language features introduced by TS for the flexibility of the language. These features will help us deal with complex and changeable development scenarios. This article will talk about the intersection type and index type of TS. 1. Intersection […]
Tag: dex
Database: Stored Procedures, Triggers, Indexing Experiments
Homework content – stored procedures and triggers, indexing experiments 1. Stored procedure and trigger experiment 1. Please implement at least one stored procedure for each of the following operations on the database platform you choose according to your application scenario: 1) Single or multi-table query 2) Data insertion 3) Data deletion 4) Data modification 2. […]
MySQL index optimization practice & EXPLAIN analysis
Let’s introduce the specific business scenario first When the user logs in, he needs to view the courses that he can learn. Different users see different courses. The courses have permissions. The permissions are controlled by the following lesson_user_permissions table, where sys_user_id and lesson_id are used as the joint primary key There is also a […]
Index coverage, index pushdown, index diving, index merging for MySQL query performance optimization
Index coverage What is index coverage The data columns of select can only be obtained from the index without reading the data rows, in other words, the query columns must be covered by the built index. How to achieve index coverage? The most common method is: build the field to be queried into a joint […]
Feature scaling (Scale Features), feature scaling prediction? CO2 value, df column index expansion
Directory 1. Feature scaling 2. Predict CO2 value 3, df column index expansion 1. Feature scaling Feature scaling can be used for different units of measure. In the case of different measurement units, the numerical size of the features will also be different, which may affect the performance of some machine learning algorithms. For example, […]
Python Teaching | Pandas Data Indexing and Data Selection
Directory Part 1 Preface Index of Part 2 Tabular Data Part 3 Pandas data selection 1. Select the data field 2. Select data row 3. Select a single data value 4. Select any data (1) Select according to the index: loc function (2) Select according to the order: iloc function What is the use of […]
Android development adds index ceiling effect
Android development adds index ceiling effect import android.graphics.Canvas import android. graphics. Paint import android.graphics.Rect import android.view.View import androidx.recyclerview.widget.RecyclerView import com.purui.mobile.R import com.purui.mobile.base.dip2sp import com.purui.mobile.utils.ResUtils abstract class StickyItemDecoration: RecyclerView.ItemDecoration() {<!– –> companion object {<!– –> // margin private val indexPaddingHorizontal = ResUtils.getDimenF(R.dimen.letter_padding_start) // index text color private val indexFontColor = ResUtils.getColor(R.color.font_color_dark) // index bar background color […]
Data structure of MySQL index
1. Why use an index An index is a data structure used by a storage engine to quickly find data records. It is like the table of contents of a textbook. By finding the page number of the corresponding article in the table of contents, you can quickly locate the desired article. The same is […]
ElasticSearch advanced query and indexing principle
Write the directory title here Advanced Search ==MATCHING Query[match_all]== ==keyword query [term]== range query [range] prefix query [prefix] Wildcard query [wildcard] Query by id array [ids] Fuzzy query [fuzzy] Boolean query [bool] must query should query must_not query filter query Boolean combination query Multi-field query [multi_match] Default field word segmentation query [query_string] Highlight query [highlight] […]
Elasticsearch index principle
Introduction Elasticsearch is a distributed and scalable real-time search and analysis engine, a search engine based on the full-text search engine Apache Lucene(TM). Of course, Elasticsearch is not just as simple as Lucene, it not only includes full-text search functions, but also The following work can be done: Distributed real-time file storage, and each field […]