在面试的时候你会被问到各种各样的怪问题，在绞尽脑汁想着解决方案的时候你或许可以从实际的角度给出最完美的方案。 以下举个数据库相关的面试问题： CSDN论坛帖子总量的统计，要求实时更新！ MyISAM 存储引擎的情况SELECT COUNT(*)的Query就能解决了！注：M
在面试的时候你会被问到各种各样的怪问题，在绞尽脑汁想着解决方案的时候你或许可以从实际的角度给出最完美的方案。
以下举个数据库相关的面试问题：
CSDN论坛帖子总量的统计，要求实时更新！
MyISAM 存储引擎的情况SELECT COUNT(*)的Query就能解决了！注：MyISAM 存储引擎互联网基本不会选择。
Innodb 存储引擎的情况呢？千万的帖子呢？访问量再大一点呢？
或许有些哥们会想到增加一个统计表，每次有新的帖子产生的时候，都将统计表中统计量这个值增加1，
这个哥们的方法肯定能解决查询的问题不错，但是高峰时期可能每秒就有几十甚至上百个帖子新增操作的时候呢？
又是一场噩梦了，是不是......
其实这种问题我们换个思维，这是一个合理的需求吗？明显需求造成的资源投入产出比相当低。
多少人会关心实时更新的帖子总量统计？有谁会在乎这个数据短时间内的不准确性？
其实去掉实时更新这个问题就很好解决了，创建一张统计表，隔一段时间去统计一次就OK了，不是吗？
这样既可以解决统计值查询的效率问题，又可以保证不影响新发贴的效率，一举两得。
别看这个问题出现的不多，其实实际有很多类似的功能，如：某些表达到一个数量级之后，我们去分页显示他的时候，完全可以
不用准确的显示这个列表总共有多少条信息，总共分了多少页，而只需要一个大概的估计值或者一个时间段之前的统计值就OK了。
这样也可用省去实时大数据的COUNT操作。
总结：从面试题看生产，很多时候我们可用换个角度思考问题，更多的发散思维。
从需求性看实际，并非一味的实时和精准是比较好的，有价值的方案。
从问题出发，我们更需要的是知道问题的本质原因。
Explain the ACID properties (Atomicity, Consistency, Isolation, Durability).Apr 16, 2025 am 12:20 AMACID attributes include atomicity, consistency, isolation and durability, and are the cornerstone of database design. 1. Atomicity ensures that the transaction is either completely successful or completely failed. 2. Consistency ensures that the database remains consistent before and after a transaction. 3. Isolation ensures that transactions do not interfere with each other. 4. Persistence ensures that data is permanently saved after transaction submission.
MySQL: Database Management System vs. Programming LanguageApr 16, 2025 am 12:19 AMMySQL is not only a database management system (DBMS) but also closely related to programming languages. 1) As a DBMS, MySQL is used to store, organize and retrieve data, and optimizing indexes can improve query performance. 2) Combining SQL with programming languages, embedded in Python, using ORM tools such as SQLAlchemy can simplify operations. 3) Performance optimization includes indexing, querying, caching, library and table division and transaction management.
MySQL: Managing Data with SQL CommandsApr 16, 2025 am 12:19 AMMySQL uses SQL commands to manage data. 1. Basic commands include SELECT, INSERT, UPDATE and DELETE. 2. Advanced usage involves JOIN, subquery and aggregate functions. 3. Common errors include syntax, logic and performance issues. 4. Optimization tips include using indexes, avoiding SELECT* and using LIMIT.
MySQL's Purpose: Storing and Managing Data EffectivelyApr 16, 2025 am 12:16 AMMySQL is an efficient relational database management system suitable for storing and managing data. Its advantages include high-performance queries, flexible transaction processing and rich data types. In practical applications, MySQL is often used in e-commerce platforms, social networks and content management systems, but attention should be paid to performance optimization, data security and scalability.
SQL and MySQL: Understanding the RelationshipApr 16, 2025 am 12:14 AMThe relationship between SQL and MySQL is the relationship between standard languages and specific implementations. 1.SQL is a standard language used to manage and operate relational databases, allowing data addition, deletion, modification and query. 2.MySQL is a specific database management system that uses SQL as its operating language and provides efficient data storage and management.
Explain the role of InnoDB redo logs and undo logs.Apr 15, 2025 am 12:16 AMInnoDB uses redologs and undologs to ensure data consistency and reliability. 1.redologs record data page modification to ensure crash recovery and transaction persistence. 2.undologs records the original data value and supports transaction rollback and MVCC.
What are the key metrics to look for in an EXPLAIN output (type, key, rows, Extra)?Apr 15, 2025 am 12:15 AMKey metrics for EXPLAIN commands include type, key, rows, and Extra. 1) The type reflects the access type of the query. The higher the value, the higher the efficiency, such as const is better than ALL. 2) The key displays the index used, and NULL indicates no index. 3) rows estimates the number of scanned rows, affecting query performance. 4) Extra provides additional information, such as Usingfilesort prompts that it needs to be optimized.
What is the Using temporary status in EXPLAIN and how to avoid it?Apr 15, 2025 am 12:14 AMUsingtemporary indicates that the need to create temporary tables in MySQL queries, which are commonly found in ORDERBY using DISTINCT, GROUPBY, or non-indexed columns. You can avoid the occurrence of indexes and rewrite queries and improve query performance. Specifically, when Usingtemporary appears in EXPLAIN output, it means that MySQL needs to create temporary tables to handle queries. This usually occurs when: 1) deduplication or grouping when using DISTINCT or GROUPBY; 2) sort when ORDERBY contains non-index columns; 3) use complex subquery or join operations. Optimization methods include: 1) ORDERBY and GROUPB
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Atom editor mac version download
The most popular open source editor
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function
Dreamweaver Mac version
Visual web development tools
Notepad++7.3.1
Easy-to-use and free code editor
