Tag:Read data

  • MySQL lock mechanism


    Interior lock MySQL performs internal locking within its own server to manage contention for table content by multiple sessions. Internal lock can be divided into row lock and table lock. External lock MySQL provides options for client sessions to explicitly acquire table locks to prevent other sessions from accessing tables. You can use the lock […]

  • Detailed explanation of [golang] channel


    Channel is a type pipe through which messages can be sent and received between goroutines. It is the communication mode between goroutines provided by golang at the language level. As we all know, go relies on a concurrency model called CSP (communicating sequential processes), which is implemented by channel. The core philosophy of go concurrency […]

  • Tensorflow course (first two) — polynomial regression


    Series articles: Tensorflow tutorial (first one) — linear regression Tensorflow course (first two) — polynomial regression Tensorflow tutorial (first three) — Logical Regression Tensorflow course (1) — linear model Standard equation method There is not only gradient descent method to solve the cost function, but also the gradient descent method needs to select the appropriate […]

  • A memory error in golang channel


    cause Cause investigation Cause analysis Problem solving summary cause In today’s database data reading, we first write the data read from the database to the channel through multiple goroutines, and at the same time read the data from the channel through another goroutine for analysis This is such a simple function. When reading data, the […]

  • Android serialization 17 – use shared preference to save and read data


    1、 There are three ways to get the sharedpreference object: The first method has been serialized last time and will not be repeated this time The second way: use the getpreference () method in activity This method is very similar to the getsharedprences() method in context, but it only accepts one operation mode parameter, because […]

  • Why should slab be colored


    In brief, when the CPU reads the memory, it does not directly go to the memory to read, which will cause the data to be read very slowly. The CPU will read the required data from the first level cache, while the first level cache will read the data from the memory in the form […]

  • Big data component building, version conflict solution


    Recently, due to the establishment of Hadoop, Flink, Kafka environment, we need to do a whole set of big data solutions.Take the corresponding official website to view the latest situation of several components.Hadoop selects CDH, and the latest version is cdh6.0.0. The corresponding versions of HBase, hive, spark are as follows: assembly edition Release CDH […]

  • Timeout problem in [PHP] socket client


    Connection socket is divided into connection timeout and read timeout $sock=stream_ socket_ client(” www.google.com : 80 “, $errno, $errstr, 2); that number is the connection timeout. For example, if you connect to Google, an error will be returned in 2 seconds, so that you won’t be waiting there all the time stream_ set_ Timeout ($sock, […]

  • Is bigger CPU cache better? What pits have you stepped on?


    In the CPU parameters, in addition to the common core threads and various frequencies, we often see a parameter called cache, some of which are 9mb, some are 16MB, and even 72mb on the third generation of sharp dragon. What is the purpose of these caches? 3800X Let’s talk about the concept first. The purpose […]

  • Go language series redis


    Use of redis Basic introduction to redis Redis is a NoSQL database, not a traditional relational database official website https://redis.io/ And http://www.redis.cn/ Redis:REmote DIctionary Server (remote dictionary server). The performance of redis is very high. A single machine can reach 15W QPS. It is usually suitable for caching and persistence. It is a fully open […]

  • Mybatis transaction management


    1. What is business A transaction is a series of rigorous operations in an application. All operations must be completed successfully, otherwise all changes made in each operation will be undone. It can be understood as: the program execution unit that updates various data items in the database. For example: grasshoppers on the same rope […]

  • Express framework learning to write simple API


    I’ve seen the API for so long, but I haven’t studied it carefully. It’s time to have a look. Initialization environment npm init -y npm i -S express Write an API document Create a JSON file to store the data { “user1” : { “name” : “mahesh”, “password” : “password1”, “profession” : “teacher”, “id”: 1 […]