what actual time

Most transactional storage engines in MySQL do not implement simple row-level locks. They generally implement multi-version concurrency control (MVCC) based on the consideration of improving concurrency performance. Not only MySQL, including

Java operation date/time, often involves calendar,date,dateformat these classes. Recently decided to organize these content system, so later use, will be more handy. This chapter focuses on "Java time frame" and "Class Calendar". In learning the

The MVCC of InnoDB is achieved by saving three hidden columns after each row of records, one of the two columns that saved the creation time of the row, the expiration time (or deletion time) of a saved row. Of course, it is not the actual time

This post was last edited by LUK on 2014-9-21 22:39Ideas:1 focus on MySQL three performance indicators, respectively, query number, transaction number, IO request number2 in a certain timeframe (for example, 20 seconds), the total number of three

First, select the appropriate data type1. CHAR vs Vchar Char is a fixed-length character type, and varchar is a variable-length character type. CHAR (m) in the data column, each value occupies M bytes, if a length less than M,mysql will be on its

From MySQL High performance third edition:We illustrate how MVCC works by InnoDB's streamlined behavior.InnoDB's MVCC is achieved by saving two hidden columns after each row of records. These two columns, one saves the creation time of the row, and

Original address: http://blog.csdn.net/csj50/article/details/5687850 a principle difference Generally in the browser to enter the URL access to resources are through the Get method, in the form submission, you can specify the way to submit the

Transferred from: http://blog.chinaunix.net/space.php?uid=10995602&do=blog&id=2918725 The process of audio and video is finished, and the next step is to see Audio and Video Synchronization (synchronization) problems. Opencore's approach is to set

Choose the right data typeWhen using MySQL to create a data table, you will encounter a problem, how to choose the appropriate data type for the field. For example, to create an employee information table, each field can be defined in many different

turn from the internet to tidy up.Advanced step of optimization--design and optimization of tableOptimize ①: Create normalized tables to eliminate data redundancyDatabase paradigm is a database design method that ensures reasonable database

Oracle Execution PlanRecently has been dealing with Oracle, from the initial face of the confused to now slightly know, also to summarize their recent studies, not regularly updated ing ...One: What is the Oracle execution plan?Execution plan is a

Environment descriptionMySQL version: percona-server-5.6.30ip:10.7.15.167Port: 3306Installation directory:/httx/run/mysqlData Catalog:/httx/run/mysql/data/Common parameters of MysqldumpMysqldump Test--– Study on the difference of –single_transaction

BodyIn the previous chapter, we learned the installation of MySQL software, since the software has been installed, now formally start the basic knowledge of MySQL learning bar, even if the 0 basis, but also to step by step. Well, the first thing to

MVCC snapshot Isolation level for SQL ServerMVCCProduct Introduction edit Multi-version Concurrency Control multiple versioning concurrency controls most MySQL transactional storage engines, such as Innodb,falcon and PBXT, do not use a simple

First, IntroductionThis article is based on the Linux Kernel Version 4.13.0-36-generic Source code, to carry out in-depth analysis of its process model, specifically contains the following:1. How the operating system organizes processes2. How

Original link: http://blog.scoutapp.com/articles/2009/07/31/understanding-load-averagesYou may have a good understanding of the load average (load averages) for Linux. The load mean can be seen in the uptime or the top command, and they may appear

SQL Server timestamp timestampIn SQL Server Books Online, it says:The SQL Server timestamp data type is independent of time and date. SQL Server Timestamp is a binary number that indicates the relative order in which data modifications occur in the

TimeStampThe SQL Server timestamp data type is independent of time and date. SQL Server Timestamp is a binary number that indicates the relative order in which data modifications occur in the database. The implementation of the timestamp data type

The concept of time stamp has been vague, I believe a lot of friends will be mistaken: Timestamp is a Time field, each time you add data, fill in the current time value. In fact, this misled a lot of friends.1. Basic ConceptsTimestamp: A unique

InnoDB and MyISAM are the two most common table types that many people use when using MySQL, both of which have pros and cons, and are different after 5.7.1. Transactions and foreign keysInnoDB has transactional, rollback, crash-repair capabilities