#sql server 2012

[techdirectarchive]

How to install Endpoint Configuration Manager on HyperV VM

Microsoft integrates Configuration Manager into the Intune family of products, offering an integrated solution for managing all devices. This integration simplifies licensing and eliminates the need for complex migrations. Users can continue leveraging their existing Configuration Manager investments while tapping into the capabilities of the Microsoft cloud at their own pace. This is a…

[apcw32]

Oracle training in hyderabad

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Contact us today to learn more about our Oracle courses, training schedules, and enrollment procedures. APEC is dedicated to empowering you with the knowledge and skills required for a successful career in Oracle database management and administration!

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[dynamicscommunity101]

AX 2012 Interview Questions and Answers for Beginners and Experts

Microsoft Dynamics AX 2012 is a powerful ERP answer that facilitates organizations streamline their operations. Whether you're a newbie or an professional, making ready for an interview associated with AX 2012 requires a radical knowledge of its core standards, functionalities, and technical factors. Below is a list of commonly requested AX 2012 interview questions together with their solutions.

Basic AX 2012 Interview Questions

What is Microsoft Dynamics AX 2012?Microsoft Dynamics AX 2012 is an company aid planning (ERP) solution advanced with the aid of Microsoft. It is designed for large and mid-sized groups to manage finance, supply chain, manufacturing, and client relationship control.

What are the important thing features of AX 2012?

Role-primarily based user experience

Strong financial control skills

Advanced warehouse and deliver chain management

Workflow automation

Enhanced reporting with SSRS (SQL Server Reporting Services)

What is the distinction between AX 2009 and AX 2012?

AX 2012 introduced a new data version with the introduction of surrogate keys.

The MorphX IDE changed into replaced with the Visual Studio development environment.

Improved workflow and role-based totally get right of entry to manipulate.

What is the AOT (Application Object Tree) in AX 2012?The AOT is a hierarchical shape used to keep and manipulate objects like tables, bureaucracy, reports, lessons, and queries in AX 2012.

Explain the usage of the Data Dictionary in AX 2012.The Data Dictionary contains definitions of tables, information types, family members, and indexes utilized in AX 2012. It guarantees facts integrity and consistency across the device.

Technical AX 2012 Interview Questions

What are the distinctive sorts of tables in AX 2012?

Regular tables

Temporary tables

In Memory tables

System tables

What is the distinction between In Memory and TempDB tables?

In Memory tables shop information within the purchaser memory and aren't continual.

Temp DB tables save brief statistics in SQL Server and are session-unique.

What is X++ and the way is it utilized in AX 2012?X++ is an item-oriented programming language used in AX 2012 for growing business good judgment, creating custom modules, and automating processes.

What is the cause of the CIL (Common Intermediate Language) in AX 2012?CIL is used to convert X++ code into .NET IL, enhancing overall performance by using enabling execution at the .NET runtime degree.

How do you debug X++ code in AX 2012?Debugging may be accomplished the use of the X++ Debugger or with the aid of enabling the Just-In-Time Debugging function in Visual Studio.

Advanced AX 2012 Interview Questions

What is a Query Object in AX 2012?A Query Object is used to retrieve statistics from tables using joins, tiers, and sorting.

What are Services in AX 2012, and what sorts are to be had?

Document Services (for replacing statistics)

Custom Services (for exposing X++ logic as a carrier)

System Services (metadata, question, and user consultation offerings)

Explain the concept of Workflows in AX 2012.Workflows allow the automation of commercial enterprise techniques, together with approvals, via defining steps and assigning responsibilities to users.

What is the purpose of the SysOperation Framework in AX 2012?It is a substitute for RunBaseBatch framework, used for walking techniques asynchronously with higher scalability.

How do you optimize overall performance in AX 2012?

Using indexes effectively

Optimizing queries

Implementing caching strategies

Using batch processing for massive facts operations

Conclusion

By understanding those AX 2012 interview questions, applicants can successfully put together for interviews. Whether you're a novice or an experienced expert, gaining knowledge of those topics will boost your self assurance and help you secure a role in Microsoft Dynamics AX 2012 tasks.

[teknogelecek]

Sütun Depolama İndeksi ile Sorgu Performansını Artırın

Sütun Depolama İndeksi, SQL Server 2012 ile veri ambarı uygulamalarında devrim yaratan bir özelliktir. Bu indeks türü, büyük veri setlerini verimli bir şekilde depolamak ve sorgulamak için tasarlanmıştır. Geleneksel satır depolama yöntemlerine göre sunduğu avantajlarla, sorgu performansını önemli ölçüde artırmasıyla dikkat çeker. Sütun depolama indeksi, veri ambarlarında optimize edilmiş veri…

[techit-rp]

Inside the Mind of a Hacker: Understanding Cyber Criminals and Their Tactics

In today’s digital landscape, cybercrime has evolved into a sophisticated, multi-billion-dollar industry. Hackers operate with precision, using advanced techniques to breach security systems, steal sensitive data, and disrupt businesses. But what motivates these cybercriminals, and how do they think? To truly combat cyber threats, we must first understand the mindset of hackers and the strategies they employ.

If you're looking to safeguard yourself and build a career in cybersecurity, pursuing a Cyber Security Certification in Kolkata can equip you with the skills needed to protect against these evolving threats. Let’s dive into the mind of a hacker and explore their tactics.

The Psychology of a Hacker

1. Motivations Behind Cybercrime

Hackers are not always driven by the same goals. Understanding their motivations helps cybersecurity professionals develop better defense mechanisms. Common hacker motivations include:

Financial Gain: Cybercriminals engage in ransomware attacks, credit card fraud, and data breaches to steal money or sell information on the dark web.

Political or Ideological Beliefs: Hacktivists, such as Anonymous, target governments or corporations to protest against policies or social issues.

Espionage: State-sponsored hackers infiltrate government agencies, corporations, and research institutions to steal confidential data.

Personal Challenge or Notoriety: Some hackers break into systems purely for the thrill, to prove their skills, or to gain recognition in the hacking community.

Revenge: Disgruntled employees or individuals use hacking to sabotage organizations or individuals who have wronged them.

2. The Hacker Mindset

Hackers exhibit a combination of intelligence, curiosity, and persistence. Many have a deep understanding of coding, networking, and security vulnerabilities. Key psychological traits of hackers include:

Problem-Solving Skills: Hackers view security systems as puzzles to be cracked.

Anonymity & Deception: They leverage VPNs, proxy servers, and encryption to remain undetected.

Adaptability: As cybersecurity evolves, hackers continuously find new ways to bypass security measures.

Common Hacking Techniques and Tactics

Hackers use various methods to infiltrate systems. Some of the most common tactics include:

1. Phishing Attacks

Phishing remains one of the most effective hacking techniques. Hackers send deceptive emails or messages that trick users into revealing personal information, such as passwords and credit card details. They often impersonate banks, government agencies, or trusted brands.

Example: In 2021, a major phishing campaign targeted Microsoft users, tricking them into entering their credentials on a fake login page.

2. Malware and Ransomware

Hackers deploy malicious software (malware) to infect systems, steal data, or lock users out of their devices. Ransomware encrypts files and demands a ransom for their release.

Example: The WannaCry ransomware attack in 2017 affected over 200,000 computers worldwide, causing billions in damages.

3. Social Engineering

This tactic exploits human psychology rather than technical vulnerabilities. Hackers manipulate individuals into divulging sensitive information or granting unauthorized access.

Example: A hacker posing as an IT support technician might call an employee and ask for their login credentials.

4. SQL Injection Attacks

Hackers exploit vulnerabilities in websites that use SQL databases. By inserting malicious SQL code into input fields, they can access, modify, or delete database records.

Example: A well-known SQL injection attack targeted Yahoo! in 2012, exposing 450,000 user accounts.

5. Denial-of-Service (DoS) and Distributed Denial-of-Service (DDoS) Attacks

These attacks overwhelm a system with excessive traffic, causing it to crash and become inaccessible.

Example: In 2016, the Mirai botnet launched a massive DDoS attack on Dyn, a major DNS provider, disrupting websites like Twitter, Netflix, and PayPal.

How to Defend Against Hackers

Understanding hacker tactics is the first step in securing digital assets. Here are essential strategies to protect against cyber threats:

1. Invest in Cybersecurity Education

A Cyber Security Certification in Kolkata can provide in-depth knowledge of ethical hacking, penetration testing, and risk management, helping individuals and businesses strengthen their defenses.

2. Use Strong Passwords and Multi-Factor Authentication (MFA)

Avoid using simple or reused passwords. Implement MFA to add an extra layer of security.

3. Keep Software and Systems Updated

Outdated software contains vulnerabilities that hackers exploit. Regular updates and security patches help close these loopholes.

4. Educate Employees on Cyber Threats

Since social engineering is a major attack vector, training employees to recognize phishing emails and suspicious activities is crucial.

5. Implement Firewalls and Intrusion Detection Systems (IDS)

These tools monitor and block unauthorized access attempts, enhancing network security.

6. Regularly Backup Data

Frequent backups protect against ransomware attacks. Store backups in a secure, offline location.

7. Conduct Penetration Testing

Simulating cyberattacks through ethical hacking helps identify vulnerabilities before malicious hackers exploit them.

Conclusion

Cybercriminals are constantly evolving, using innovative tactics to breach systems and exploit vulnerabilities. By understanding their mindset and techniques, individuals and businesses can better protect themselves from cyber threats.

If you're serious about cybersecurity, obtaining a Cyber Security Certification in Kolkata is a great way to gain the skills and knowledge needed to combat cyber threats effectively. Investing in cybersecurity today can save organizations from significant financial losses, data breaches, and reputational damage in the future.

Cybersecurity is not just a technology problem—it’s a human challenge. Stay informed, stay prepared, and stay secure.

[atplblog]

Price: [price_with_discount] (as of [price_update_date] - Details) [ad_1] T-SQL insiders help you tackle your toughest queries and query-tuning problems Squeeze maximum performance and efficiency from every T-SQL query you write or tune. Four leading experts take an in-depth look at T-SQL’s internal architecture and offer advanced practical techniques for optimizing response time and resource usage. Emphasizing a correct understanding of the language and its foundations, the authors present unique solutions they have spent years developing and refining. All code and techniques are fully updated to reflect new T-SQL enhancements in Microsoft SQL Server 2014 and SQL Server 2012. Write faster, more efficient T-SQL code: Move from procedural programming to the language of sets and logicMaster an efficient top-down tuning methodologyAssess algorithmic complexity to predict performanceCompare data aggregation techniques, including new grouping setsEfficiently perform data-analysis calculationsMake the most of T-SQL’s optimized bulk import toolsAvoid date/time pitfalls that lead to buggy, poorly performing codeCreate optimized BI statistical queries without additional softwareUse programmable objects to accelerate queriesUnlock major performance improvements with In-Memory OLTPMaster useful and elegant approaches to manipulating graphs About This Book For experienced T-SQL practitionersIncludes coverage updated from Inside Microsoft SQL Server 2008 T-SQL Querying and Inside Microsoft SQL Server 2008 T-SQL ProgrammingValuable to developers, DBAs, BI professionals, and data scientistsCovers many MCSE 70-464 and MCSA/MCSE 70-461 exam topics ASIN ‏ : ‎ B00TPRWVHY Publisher ‏ : ‎ Microsoft Press; 1st edition (17 February 2015) Language ‏ : ‎ English File size ‏ : ‎ 63114 KB Simultaneous device usage ‏ : ‎ Up to 5 simultaneous devices, per publisher limits Text-to-Speech ‏ : ‎ Enabled Screen Reader ‏ : ‎ Supported Enhanced typesetting ‏ : ‎ Enabled X-Ray ‏ : ‎ Not Enabled Word Wise ‏ : ‎ Not Enabled Print length ‏ : ‎ 865 pages [ad_2]

[easyinplay]

从数据库发展历程到数据结构设计探析

一 数据库发展史

起初，数据的管理方式是文档系统，数据存储在文档中，数据管理和维护都由进程员完成。后来发展出树形结构和网状结构的数据库，但都存在着难以扩展和维护的问题。直到七十年代���关系数据库理论的提出，以表格形式组织数据，数据之间存在关联关系，具有了良好的结构化和规范化特性，成为主流数据库类型。

先来看一张数据库发展史图鉴：

随之高并发大数据时代的来临，数据库按照各种应用场景进行了更细粒度的拆分和演进，数据库细分领域的典型代表：

二 数据库名词概念

RDBS

1970 年的 6 月，IBM 公司的研究员埃德加・考特 （Edgar Frank Codd） 发表了那篇着名的《大型共享数据库数据的关系模型》（A Relational Model of Data for Large Shared Data Banks）的论文，拉开了关系型数据库（Relational DataBase Server）��件革命的序幕（之前是层次模型和网状模型数据库为主）。直到现在，关系型数据库在基础软件应用领域仍是最主要的数据存储方式之一。

关系型数据库创建在关系型数据模型的基础上，是借助于集合代数等数学概念和方法来处理数据的数据库。在关系型数据库中，实体以及实体间的联系均由单一的结构类型来表示，这种逻辑结构是一张二维表。关系型数据库以行和列的形式存储数据，这一系列的行和列被称为表，一组表组成了数据库。

NoSQL

NoSQL（Not Only SQL） 数据库也即非关系型数据库，它是在大数据的时代背景下产生的，它可以处理分布式、规模庞大、类型不确定、完整性没有保证的 “杂乱” 数据，这是传统的关系型数据库远远不能胜任的。NoSQL 数据库并没有一个统一的模型，是以牺牲事务机制和强一致性机制，来获取更好的分布式部署和横向扩展能力，使其在不同的应用场景下，对特定业务数据具有更强的处理性能。常用数据模型示例如下：

NewSQL

NewSQL 是一类新的关系型数据库， 是各种新的可扩展和高性能的数据库的简称。它不仅具有 NoSQL 数据库对海量数据的存储管理能力，同时还保留了传统数据库支持的 ACID 和 SQL 特性，典型代表有 TiDB 和 OceanBase。

OLTP

联机事务处理过程 (On-Line Transaction Processing)：也称为面向交易的处理过程，其基本特征是前台接收的用户数据可以立即传送到计算中心进行处理，并在很短的时间内给出处理结果，是对用户操作快速响应的方式之一。

OLAP

联机分析处理（On-Line Analytical Processing）是一种面向数据分析的处理过程，它使分析人员能够迅速、一致、交互地从各个方面观察信息，以达到深入理解数据的目的。它具有 FASMI (Fast Analysis of Shared Multidimensional Information)，即共享多维信息的快速分析的特征。

关于 OLTP 和 OLAP 的区别，借用一张表格对比如下：

HTAP (Hybrid Transactional/Analytical Processing) 混合型数据库基于新的计算存储框架，能够同时支撑 OLTP 和 OLAP 场景，避免传统架构中大量数据交互造成的资源浪费和冲突。

三 领域数据库

列式数据库

传统的以行形式保存的数据主要满足 OLTP 应用，列形式保存的数据主要满足以查询为主的 OLAP 应用。在列式数据库中，数据按列存储，而每个列中的数据类型相同。这种存储方式使列式数据库能够更高效地处理大量的数据，特别是需要进行大规模的数据分析和处理时（如金融、医疗、电信、能源、物流等行业）。

两种存储结构的区别如下图：

列式数据库的主要优点：

• 更高的压缩比率：由于每个列中的数据类型相同，列式数据库可以使用更高效的压缩算法来压缩数据（压缩比可达到 5～20 倍），从而减少存储空间的使用。

• 更快的查询速度：列式数据库可以只读取需要的列，而不需要读取整行数据，从而加快查询速度。

• 更好的扩展性：列式数据库可以更容易地进行水平扩展，即增加更多的节点和服务器来处理更大规模的数据。

• 更好的数据分析支持：由于列式数据库可以处理大规模的数据，它可以支持更复杂的数据分析和处理操作，例如数据挖掘、机器学习等。

列式数据库的主要缺点：

• 更慢的写入速度：由于数据是按列存储，每次写入都需要写入整个列，而不是单个行，因此写入速度可能较慢。

• 更复杂的数据模型：由于数据是按列存储，数据模型可能比行式数据库更复杂，需要更多的设计和开发工作。

列式数据库的应用场景：

• 金融：金融行业的交易数据和市场数据，例如股票价格、外汇汇率、利率等。列式数据库可以更快速地处理这些数据，并且支持更复杂的数据分析和处理操作，例如风险管理、投资分析等。

• 医疗：医疗行业的病历数据、医疗图像和实验数据等。列式数据库可以更高效地存储和处理这些数据，并且支持更复杂的医学研究和分析操作。

• 电信：电信行业的用户数据和通信数据，例如电话记录、短信记录、网络流量等。列式数据库可以更快速地处理这些数据，并且支持更复杂的用户行为分析和网络优化操作。

• 能源：能源行业的传感器数据、监测数据和生产数据等。列式数据库可以更高效地存储和处理这些数据，并且支持更复杂的能源管理和控制操作。

• 物流：物流行业的运输数据、库存数据和订单数据等。列式数据库可以更快速地处理这些数据，并且支持更复杂的物流管理和优化操作。

总之，列式数据库是一种高效处理大规模数据的数据库管理系统，但需要权衡写入速度、数据模型复杂度和成本等因素。 随着传统关系型数据库与新兴的分布式数据库不断的发展，列式存储与行式存储会不断融合，数据库系统呈现双模式数据存放方式。

时序数据库

时序数据库全称为时间串行数据库 (Time Series Database)，用于存储和管理时间串行数据的专业化数据库，是优化用于摄取、处理和存储时间戳数据的数据库。其跟常规的关系数据库 SQL 相比，最大的区别在于：时序数据库是以时间为索引的规律性时间间隔记录的数据库。

时序数据库在物联网和互联网应用进程监控（APM）等场景应用比较多，以监控数据采集来举例，如果数据监控数据采集时间间隔是 1s，那一个监控项每天会产生 86400 个数据点，若有 10000 个监控项，则一天就会产生 864000000 个数据点。在物联网场景下，这个数字会更大，整个数据的规模，是 TB 甚至是 PB 级的。

时序数据库发展史：

当下最常见的 Kubernetes 容器管理系统中，通常会搭配普罗米修斯（Prometheus）进行监控，Prometheus 就是一套开源的监控 & 报警 & 时间串行数据���的组合。

图数据库

图数据库（Graph Database）是基于图论实现的一种新型 NoSQL 数据库。它的数据存储结构和数据的查询方式都是以图论为基础的。图论中图的基本元素为节点和边，在图数据库中对应的就是节点和关系。

图数据库在反欺诈多维关联分析场景，社交网络图谱，企业关系图谱等场景中可以做一些非常复杂的关系查询。这是由于图数据结构表现的是实体联系本身，它表现了现实世界中事物联系的本质，它的联系在节点创建时就已经创建，所以在查询中能以快捷的路径返回关联数据，从而表现出非常高效的查询性能。

目前市面上较为流行的图数据库产品有以下几种：

与传统的关系数据库相比，图数据库具有以下优点：

1. 更快的查询速度：图数据库可以快速遍历图数据，找到节点之间的关联和路径，因此查询速度更快。

2. 更好的扩展性：图数据库可以轻松地扩展到大规模的数据集，因为它们可以分布式存储和处理数据。

3. 更好的数据可视化：图数据库可以将数据可视化为图形，使用户更容易理解和分析数据。

4. 更好的数据一致性：图数据库可以确保数据的一致性，因为它们可以在节点和边之间创建强制性的关系。

四 数据结构设计

前面简单介绍了数据库相关的基础知识，下面再介绍几种我们常见的数据结构设计相关的应用实践：拉链表，位运算和环形队列。

4.1 拉链表

拉链表是一种数据仓库中常用的数据模型，用于记录维度数据的变化历史。我们以一个人员变动的场景举例，假设有一个员工信息表，其中包含了员工的姓名、工号、职位、部门、入职时间等信息。如果需要记录员工的变动情况，就可以使用拉链表来实现。

首先，在员工信息表的基础上添加两个字段：生效时间和失效时间。当员工信息发生变动时，不再添加一条记录，而是修改原有记录的失效时间，同时添加一条新的记录。如下表所示：

这里的生效时间指的是该记录生效的时间，失效时间指的是该记录失效的时间。例如，张三最初是技术部经理，生效时间为入职时间，失效时间为 2012 年底，之后晋升为技术部总监，生效时间为 2013 年初，失效时间为 2015 年底，最后又晋升为技术部总经理，生效时间为 2016 年初，失效时间为 9999 年底。

通过这种方式，可以记录员工变动的历史信息，并能够方便地查询某个时间点的员工信息。例如，如果需要查询张三在 2014 年的职位和部门信息，只需查询生效时间小于 2014 年且失效时间大于 2014 年的记录即可。

拉链表通常包括以下几个字段：

1.主键：唯一标识每个记录的���段，通常是一个或多个列的组合。 2.生效时间：记录的生效时间，即该记录开始生效的时间。 3.失效时间：记录的失效时间，即该记录失效的时间。 4.版本号：记录的版本号，用于标识该记录的版本。 5.其他维度属性：记录的其他维度属性，如客户名、产品名、员工名等。

当一个记录的维度属性发生变化时，不再添加一条记录，而是修改原有记录的失效时间，同时添加一条新的记录。新记录的生效时间为变化的时间，失效时间为 9999 年底。这样就能够记录每个维度属性的历史变化信息，同时保证查询时能够正确获取某个时间点的维度属性信息。

拉链表与传统的流水表相比，它们的主要区别在于：

1. 数据结构不同：流水表是一张只有添加和更新操作的表，每次更新都会添加一条记录，记录中包含了所有的历史信息。而拉链表则是一张有添加、更新和删除操作的表，每个记录都有一个生效时间段和失效时间段，记录的历史信息通过时间段的变化来体现。

2. 查询方式不同：流水表的查询方式是基于时间点的查询，即查询某个时间点的记录信息。而拉链表的查询方式是基于时间段的查询，即查询某个时间段内的记录信息。

3. 存储空间不同：由于流水表需要记录所有历史信息，所以存储空间相对较大。而拉链表只记录生效时间段和失效时间段，所以存储空间相对较小。

4. 数据更新方式不同：流水表只有添加和更新操作，每次更新都会添加一条记录，不会对原有记录进行修改。而拉链表有添加、更新和删除操作，每次更新会修改原有记录的失效时间，同时添加一条新的记录。

4.2 巧用位运算

借助于计算机位运算的特性，可以巧妙的解决某些特定问题，使实现更加优雅，节省存储空间的同时，也可以提高运行效率，典型应用场景：压缩存储、位图索引、数据加密、图形处理和状态判断等，下面介绍几个典型案例。

4.2.1 位运算

• 使用位运算实现开关和多选项叠加（资源权限）等应用场景。一个 int 类型有 32 个位，理论上可以表示 32 个开关状态或业务选项；以用户每个月的签到场景举例：用一个 int 字段来表示用户一个月的签到情况，0 表示未签到，1 表示签到。想知道某一天是否签到，则只需要判断对应的比特位上是否为 1。计算一个月累计签到了多少次，只需要统计有多少个比特位为 1 就可以了。这种设计巧妙的数据存储结构在后面的位图（BitMap）中，还会进行更为详细的介绍。

• 使用位运算实现业务优先级计算：

• 其它使用位运算的典型场景：HashMap 中的队列长度的设计和线程池 ThreadPoolExcutor 中使用 AtomicInteger 字段 ctl，存储当前线程池状态和线程数量（高 3 位表示当前线程的状态，低 29 位表示线程的数量）。

4.2.2 BitMap

位图（BitMap）是一种常用的数据结构，在索引，数据压缩等方面有广泛应用。基本思想就是用一个 bit 位来标记某个元素对应的 Value，而 Key 即是该元素。由于采用了 Bit 为单位来存储数据，因此可以大大节省存储空间，是少有的既能保证存储空间又能保证查找速度的数据结构（而不必空间换时间）。

举个例子，假设有这样一个需求：在 20 亿个随机整数中找出某个数 m 是否存在其中，并假设 32 位操作系统，4G 内存，在 Java 中，int 占 4 字节，1 字节 = 8 位（1 byte = 8 bit）。

• 如果每个数字用 int 存储，那就是 20 亿个 int，因而占用的空间约为 (2000000000*4/1024/1024/1024)≈7.45G

• 如果按位存储就不一样了，20 亿个数就是 20 亿位，占用空间约为 (2000000000/8/1024/1024/1024)≈0.233G

存储空间可以压缩节省 31 倍！那么它是如何通过二进制位实现数字标记的呢？ 其原理是用每个二进制位（下标）表示一个真实数字，0 表示不存在，1 表示存在，这样我们可以很容易表示 {1,2,4,6} 这几个数：

计算机内存分配的最小单位是字节，也就是 8 位，那如果要表示 {12,13,15} 怎么办呢？可以另申请一个字节 b [1]：

通过一个二维数组来实现位数叠加，1 个 int 占 32 位，那么我们只需要申请一个 int 数组长度为 int index [1+N/32] 即可存储，其中 N 表示要存储的这些数中的最大值：

index [0]：可以表示 0\~31

index [1]：可以表示 32\~63

index [2]：可以表示 64\~95

以此类推 ... 如此一来，给定任意整数 M，那么 M/32 就得到下标，M%32 就知道它在此下标的哪个位置。

BitMap 数据结构通常用于以下场景：

1. 压缩存储大量布尔值：BitMap 可以有效地压缩大量的布尔值，从而减少内存的使用；

2. 快速判断一个元素是否存在：BitMap 可以快速地判断一个元素是否存在，只需要查找对应的位即可；

3. 去重：BitMap 可以用于去重操作，将元素作为索引，将对应的位设置为 1，重复元素只会对应同一个位，从而实现去重；

4. 排序：BitMap 可以用于排序，将元素作为索引，将对应的位设置为 1，然后按照索引顺序遍历位数组，即可得到有序的元素串行；

5. ElasticSearch 和 Solr 等搜索引擎中，在设计搜索剪枝时，需要保存已经搜索过的历史信息，可以使用位图减小历史信息数据所占空间；

4.2.3 布���过滤器

位图（Bitmap）这种数据存储结构，如果数据量大到一定程度，比如 64bit 类型的数据，简单算一下存储空间就知道，海量硬件资源要求，已经不太现实了：

所以另一个着名的工业实现 - 布隆过滤器（Bloom Filter）出现了。如果说 BitMap 对于每一个可能的整型值，通过直接寻址的方式进行映射，相当于使用了一个哈希函数，那布隆过滤器就是引入了 k (k> 1 ) 个相互独立的哈希函数，保证在给定的空间和误判率情况下，完成元素判重的过程。下图中是 k = 3 时的布隆过滤器：

布隆过滤器的内部依赖于哈希算法，当检测某一条数据是否见过时，有一定概率出现假阳性（False Positive），但一定不会出现假阴性（False Negative）。也就是说，当 布隆过滤器认为一条数据出现过，那么该条数据很可能出现过；但如果布隆过滤器认为一条数据没出现过，那么该条数据一定没出现过。布隆过滤器通过引入一定错误率，使得海量数据判重在可以接受的内存代价中得以实现。

上图中，x,y,z 经由哈希函数映射将各自在 Bitmap 中的 3 个位置置为 1，当 w 出现时，仅当 3 个标志位都为 1 时，才表示 w 在集合中。图中所示的情况，布隆过滤器将判定 w 不在集合中。

常见实现

• Java 中 Guava 工具包中实现；

• Redis 4.0 开始以插件形式提供布隆过滤器功能；

适用场景

• 网页爬虫对 URL 的去重，避免爬去相同的 URL 地址，比如 Chrome 浏览器就是使用了一个布隆过滤器识别恶意链接；

• 垃圾邮件过滤，从数十亿个垃圾邮件列表中判断某邮箱是否是杀垃圾邮箱；

• 解决数据库缓存击穿，黑客攻击服务器时，会构建大量不存在于缓存中的 key 向服务器发起请求，在数据量足够大的时候，频繁的数据库查询会导致挂机；

• 谷歌 Bigtable、Apache HBase、Apache Cassandra 和 PostgreSQL 使用布隆过滤器来减少对不存在的行或列的磁盘查找；

• 秒杀系统，查看用户是否重复购买；

4.2.4 小结

• 位运算有着执行速度快，占用空间小，代码实现简洁等优点，往往能起到四两拨千斤的效果。同样也有着代码可读性差，使用范围和可维护性受限等不足；

• 在 BitMap 中，占用空间大小还与实际应用场景有关，这种结构无法容忍误判，只能判断一个元素是否存在，如果数据离散度过高，空间利用率反而更低；

• 布隆过滤器则有着空间利用率高，可以容忍一定的误判率的优点。与 BitMap 相比，也存在着无法删除元素，误判率无法达到 0 等不足；

4.3 环形队列

环形队列是一种用于表示一个固定尺寸、头尾相连的数据结构，很适合缓存数据流。在通信开发（Socket，TCP/IP，RPC 开发），在内核的进程间通信（IPC），视频音频播放等各种场景中，都有其身影。日常开发过程中使用的 Dubbo、Netty、Akka、Quartz、ZooKeeper 、Kafka 等各种中间件，也都有环形队列的思想。下面介绍两种常用的环形数据结构：Hash 环和时间轮。

4.3.1 一致性 Hash 环

先来看一下，典型 Hash 算法结构如下：

以上图 Hash 策略为例，当节点数 N 发生变化的时候 之前所有的 hash 映射几乎全部失效，如果集群是无状态的服务，倒是没什么事情，但是如果是分布式缓存这种场景，就会导致比较严重的问题。比如 Key1 原本是路由到 Node1 上，命中缓存的 Value1 数据。但是当 N 节点变化后，Key1 可能就路由到了 Node2 节点，这就产生了缓存数据无法命中的问题。而无论是机器故障还是缓存扩容，都会导致节点数的变化。

如何解决上面场景的问题呢？就是接下来介绍的一致性 Hash 算法。

一致性哈希将整个哈希值空间组织成一个虚拟的圆环，假设某哈希函数 H 的值空间为 0-2^32-1（即哈希值是一个 32 位无符号整型），所有的输入值都被映射到 0-2^32-1 之间，组成一个圆环。整个哈希空间环如下：

路由数据的过程如下：将数据 key 使用相同的函数 Hash 计算出哈希值，并确定此数据在环上的位置，从此位置沿环顺时针 “行走”，遇到的第一个节点就是其应该定位到的服务器。如果某个节点的服务器故障，其影响范围也不再是所有集群，而是限定在故障节点与其上游节点的���分区域。

当某个节点宕机后，原本属于它的请求都会被重新 hash 映射到下游节点，会突然造成下游节点压力过大有可能也会造成下游节点宕机，从而容易形成雪崩，为此引入了虚拟节点来解决这个问题。

根据 Node 节点生成很多的虚拟节点分布在圆环上，，一个真实节点映射对应多个虚拟节点。这样当某个节点挂了后原本属于它的请求，会被均衡的分布到其他节点上降低了产生雪崩的情况，也解决了物理节点数少，导致请求分布不均的问题。

带有虚拟节点的 Hash 环：

一致性 Hash 算法由于均衡性，持久性的映射特点被广泛应用于负载均衡领域，比如 nginx、dubbo 等内部都有一致性 hash 的实现。

4.3.2 时间轮分片

时间轮（TimeWheel）是一种实现延迟功能（定时器）的精妙的算法，可以实现高效的延时队列。以 Kafka 中的时间轮实现方案为例，它是一个存储定时任务的环形队列，底层采用数组实现，数组中的每个元素可以存放一个定时任务列表（TimerTaskList）。TimerTaskList 是一个环形的双向链表，链表中的每一项表示的都是定时任务项（TimerTaskEntry），其中封装了真正的定时任务 TimerTask。

通过上图可以发现，时间轮算法不再任务队列作为数据结构，轮询线程不再负责遍历所有任务，而是仅仅遍历时间刻度。时间轮算法好比指针不断在时钟上旋转、遍历，如果一个发现某一时刻上有任务（任务队列），那么就会将任务队列上的所有任务都执行一遍。

假设相邻 bucket 到期时间的间隔为 bucket=1s，从 0s 开始计时，1s 后到期的定时任务挂在 bucket=1 下，2s 后到期的定时任务挂在 bucket=2 下，当检查到时间过去了 1s 时，bucket=1 下所有节点执行超时动作，当时间到了 2s 时，bucket=2 下所有节点执行超时动作。时间轮使用一个表盘指针（pointer），用来表示时间轮当前指针跳动的次数，可以用 tickDuration * (pointer + 1) 来表示下一次到期的任务，需要处理此 bucket 所对应的 TimeWheel 中的所有任务。

时间轮的优点

1. 任务的添加与移除，都是 O (1) 级的复杂度；

2. 只需要有一个线程去推进时间轮，不会占用大量的资源；

3. 与其他任务调度模式相比，CPU 的负载和资源浪费减少；

适用场景

时间轮是为解决高效调度任务而产生的调度模型。在周期性定时任务，延时任务，通知任务等场景都可以发挥效用。

五 总结

本文针对数据存储相关名词概念进行了解释，重点介绍了数据库技术的发展史。为了丰富文章的可读性以及实用性，又从数据结构设计层面进行了部分技术实战能力的外延扩展，阐述了拉链表，位运算，环形队列等相关数据结构在软件开发领域的应用，希望本文给你带来收获。

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How to upgrade System Center Configuration Manager 2012 to SP1

How to upgrade System Center Configuration Manager 2012 to SP1 | https://tinyurl.com/2dakodaa | #Guide #SCCM #WSUS This is a guide on upgrading System Center Configuration Manager 2012 to Service Pack 1 in a lab environment. Your setup may be slightly different so remember this is a guide, so if you have any questions, please feel free to leave a comment at the bottom of this post. Note that I am using the following setup: Domain Controller – Windows Server 2008 R2 SQL Server – Windows Server 2008 R2 & SQL Server 2008 R2 CM2012 Server – Windows Server 2008 R2 DP Server – Windows Server 2008 R2 All these servers are obviously x64 so the download […] Read more... https://tinyurl.com/2dakodaa

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Essential AX 2012 Interview Questions

Introduction

Many businesses utilize Microsoft Dynamics AX 2012, a powerful enterprise resource planning (ERP) tool, to optimize their company processes. Companies are looking for qualified candidates to manage, optimize, and deploy their AX 2012 systems, so being prepared for the kinds of questions you might be asked during an interview can greatly increase your chances of getting the job. This post examines important interview questions about ax 2012 interview questions and provides advice on how to be well-prepared.

Typical Interview Questions for AX 2012

Could you describe the main features and modules of Dynamics AX 2012?

Provide an explanation of the primary modules, including project management, sales and marketing, supply chain management, human resources, and financial management. Emphasize the features of every module, including inventory control, sales order processing, and financial reporting handling, as well as personnel administration.

How do you manage AX 2012 customizations?

Answer Tip: Talk about how to create customizations using AX 2012 using the programming language X++. Describe the changes you make to forms, the fields you add, and the features you add to standard modules. Stress how crucial it is to strike a balance between custom features and default features in order to sustain system upgrades and maintainability.

What does AX 2012's Application Object Tree (AOT) serve as?

Answer Tip: In order to manage and arrange the application's objects, including tables, forms, reports, and classes, the Application Object Tree (AOT) is an essential part of AX 2012. Tell us about your development, customisation, and debugging processes using the AOT.

Could you explain the AX 2012 data migrating process?

Respond Advice: Describe the processes that go into data migration, such as loading, extracting, and transforming data (ETL). Talk about techniques for guaranteeing data correctness and integrity during the migration process, as well as technologies like the Data Import Export Framework (DIXF).

In AX 2012, how are security roles and permissions implemented?

Solution Tip: Describe how security roles, responsibilities, and privileges are defined and managed in AX 2012. Describe the process you use to manage user rights and assign roles to ensure that the right people have access to the right areas of the system while also adhering to security regulations.

What are Batch Jobs in AX 2012 and how do you use them?

Answer Tip: In AX 2012, batch jobs are used to plan and carry out background operations, like reporting and data processing, without requiring user input intervention. Explain the process of creating, setting up, and keeping an eye on batch jobs in order to automate tedious work and boost system performance.

How can performance problems in AX 2012 be resolved?

Answer Tip: Talk about how you use tools like SQL Profiler and the Dynamics AX Trace Parser to diagnose performance issues, as well as how you analyze SQL Server performance and examine system logs. Stress how crucial it is to optimize system parameters and queries in order to achieve better performance.

How does Dynamics 365 Finance and Operations vary from AX 2012?

Answer Tip: Emphasize the main distinctions, such as the shift from on-premises to cloud-based solutions, modifications to the functionality and user experience, and the advancement of features and integrations. Talk about the advantages and restrictions of each version.

Could you elaborate on the idea of the AX 2012 Data Entity?

Answer Tip: In AX 2012, data import and export procedures are made easier by the usage of data entities. Describe how they differ from tables and views and how they help to simplify data administration and integration with external systems.

In AX 2012, how is data integrity and correctness ensured?

Answer Tip: Talk about the best ways to keep data accurate and consistent, including putting validation rules into place, doing routine data reconciliations, and keeping an eye on data quality with system reports. Mention particular instruments and methods employed to guarantee accurate data.

Summary

It's important to prepare for a Dynamics AX 2012 interview by familiarizing yourself with the system's main modules, customization choices, and data management procedures. By becoming knowledgeable about important subjects like the Applying your knowledge and problem-solving abilities to Application Object Tree, data migration procedures, security roles, and performance debugging, you can effectively showcase your abilities. Knowing the distinctions between AX 2012 and more recent options, such as Dynamics 365 Finance and Operations, can also demonstrate your flexibility and knowledge of current developments in ERP systems. Your career in Dynamics AX 2012 can be advanced and you will be in a position to impress prospective employers with your extensive preparation and understanding of these key principles.

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5 Ways Nopcommerce Will Help You Get More Business

In 1994, the first item ordered online at Amazon was a book. This $12.48 transaction made history and signaled the world that the “internet is open” for online transactions. Today, the e-commerce industry has grown into a trillion-dollar industry.

Data from Statista shows that e-commerce sales worldwide hit a staggering $4.3 trillion in 2021, and the number is growing by the day. With the shift towards digital retail moving at the speed of light, many companies plan to go online.

The common dilemma that many retailers face is which e-commerce platform to choose when starting their venture.

One platform—nopCommerce, stands tall above the competition, offering rich and transformational functionalities to small and medium-sized stores. We’ll delve into the crux of nopCommerce and explain why it’s the best platform for your business.

What Is nopCommerce? nopCommerce is a free and open-source ecommerce solution for all businesses. It powers tens of thousands of online stores worldwide, including reputable brands like Volvo, Reebok, North Face, and Hyatt Hotels.

ecommerce solutions The platform offers cutting-edge features and functionalities anyone would expect in a world-class e-commerce platform, including:

Product comparison tools

User reviews

Shipping management

Discount options

Marketing

Mobile access

Data security Unlike other solutions, nopCommerce is based on the ASP.NET framework and Microsoft SQL Server 2012 back-end database.

Since its inception in 2008, nopCommerce has won numerous prestigious awards, including CMScritic’s “Best eCommerce for SMB” award and the Packt Open-Source Award.

Online Business Problems that nopCommerce Solves From scale to sales, online businesses face many challenges at various stages due to primarily choosing an inadequate and inefficient eCommerce development platform. Traditional eCommerce development platforms were focused only on offering essential digital commerce solutions.

Meanwhile, modern platforms ensure customization, integration, scalability, security, and innovation for businesses to cut through competition and continuously improve their bottom line. Let’s evaluate how nopCommerce eliminates those challenges that online businesses face.

Problem: Limited Customization Nowadays, developing eCommerce platforms means selecting a template. Every business requires unique features to stand out in a crowded marketplace. A Salesforce study suggests that 64% of customers expect businesses to provide unique and tailored shopping experiences. When eCommerce development platforms do not offer customization, online businesses suffer due to a lack of trust and reliability.

Solution: nopCommerce Flexibility nopCommerce ensures that developers can modify codes the way they want and build plugins to support their eCommerce solution with unique features that competitors do not have. This open-source flexibility helps businesses craft unique user interfaces and, thereby, unique and tailored customer experiences. Integrating AI and automation solutions with an eCommerce platform becomes a catalyst in giving a brand a unique identity.

Problem: High Operational Costs Running an eCommerce store is expensive until a business reaches a breakeven point. In addition to its own offline and online operations costs, an eCommerce store requires many expensive add-on services. Integrating Cloud or RPA solutions automatically increases the costs. 43% of small business owners avoid going online due to the high costs of digital transformation, says a BigCommerce Study.

Solution: nopCommerce’s Cost-Effective Model The biggest relief for small and medium enterprises is that nopCommerce is a free eCommerce solution development platform that charges no recurring license fees. This self-hosted solution offers multiple in-built plugins to reduce the need to build costly plugins. Moreover, due to customization, businesses can have more control over features and functionalities to reduce the cost of features that come with templates. In many ways, nopCommerce stops eCommerce development costs from rising.

Problem: Poor Mobile Experience Smartphone penetration is an open secret worldwide. According to Statista analysis, mobile commerce is expected to grow to $710 billion by 2025. If an eCommerce store is not mobile-friendly, it won’t attract customers and increase conversions. Businesses that fail to provide a rich and effortless mobile experience will not only struggle against competitors but will struggle for survival.

Solution: Mobile-First Approach nopCommerce empowers eCommerce developers to build responsive user interfaces that fit all screen sizes and resolutions without incurring additional costs. nopCommerce’s mobile-first approach ensures that an eCommerce store maintains design continuity across the platforms. Besides, with mobile-friendliness, businesses can integrate and offer many mobile-only features to optimize conversion ratio through enhanced checkout processes.

Problem: Limited Scalability Imagine if a conversion rate drops by 4% for each additional second of load time. According to these statistics, businesses can’t even run their regular businesses if their eCommerce store is not scalable. Businesses are bound to grow, but their eCommerce store remains stagnant and inefficient in handling the increased traffic load and transactions. Consequently, the system gives up on increasing the load time and crashes during peak periods.

Solution: nopCommerce’s Scalable Architecture nopCommerce is a robust, secure, and scalable architecture that empowers eCommerce developers to build genuinely scalable digital commerce solutions that can house large product catalogs, run multiple stores, have wide category ranges, and handle the increased traffic effortlessly. It supports load balancing and multiple servers to keep the system optimized for additional capabilities to reduce load time, process more data, and maintain uptime during critical hours.

Problem: Inadequate Security Measures eCommerce stores are easy targets for hacking, phishing, and various other cyber threats as they house a lot of customer data and financially sensitive information. A 2023 Cybersecurity Ventures report predicts cybercrime will cost the world $10.5 trillion annually by 2025. Inadequate security apparatus invites maximum data breaches, causing massive financial and reputational losses to eCommerce businesses.

Solution: nopCommerce’s Strong Security Features Cybersecurity is of paramount importance for nopCommerce. In addition to providing quick and adequate security updates, nopCommerce delivers built-in SSL support, data encryption, and multi-layer authentication for safe and secure access. nopCommerce strictly follows PCI DSS requirements to process payments securely. Moreover, the nopCommerce community continuously identifies and updates threat potential and vulnerabilities to quickly resolve cyber threat-related issues. It also has a robust disaster recovery mechanism to protect personal and financial data.

Advantages of Using NopCommerce for Your Project With a plethora of options, it can be challenging for any business owner to determine the best ecommerce solution for their business. Here are the top reasons to choose nopCommerce for your project.

1. It’s an Open-Source Platform NopCommerce is an open-source platform, which means it’s free.

There are no upfront fees, subscription fees, or hidden fees to set it up. Anyone can download the source code and modify it to fit their custom requirements.

There is a common fallacy in the tech world that “free solutions” don’t receive security updates and aren’t backed by support.

But this is not true for nopCommerce. The platform has an active community of supporters and skilled developers who are continually working to maintain its standards and make it faster, safer, and more reliable.

2. It Offers Multi-Store Support The multi-store environment has become the new norm in the ecommerce community.

Retailers are no longer restricting the scope of their businesses to a single storefront. Instead, many are opting for multiple storefronts.

NopCommerce online retailers can set the following features separately per store:

Products per store

Product prices per store

Payments per store

Tax rules per store

Shipment methods per store

Content (newsletter, blogs, news) per store With the multi-store feature, retailers can create a nopCommerce marketplace where small vendors can sell their products separately.

3. Ready for Mobile Commerce (M-Commerce) In an age where mobile phone usage surpasses desktop, a mobile-friendly design is a must-have. Furthermore, the current shift to online shopping fueled by the novel COVID-19 pandemic has caused a surge in mobile commerce.

Experts predict that M-commerce will account for 72.3% of all sales by the end of 2021.

In line with the changing consumer behavior, savvy retailers are leveraging mobile-ready e-commerce platforms to grow sales. The nopCommerce platform offers free, mobile-friendly features that are ready to use out of the box.

In addition, nopCommerce enables store owners to easily create mobile versions of their sites without extra development work or add-ons.

4. Comes with Pre-Built Integrations Another great thing about nopCommerce is that it comes with pre-built integrations.

These integrations can save resources while allowing store owners to launch or revamp their online stores quickly. All nopCommerce integrations come from different nopCommerce developers experienced in building integrations for payments, shipping, etc.

For example, the platform is integrated with more than 50 payment getaways and methods, including PayPal, Alipay, WorldPay, and Stripe.

5. It’s Easy to Scale One of the most significant benefits that users get with nopCommerce is on-demand scalability. NopCommerce can work with cheap Windows hosting solution providers like SmarterASP and enterprise hosting solutions like Azure Cloud.

The Final Thoughts NopCommerce makes a strong case for being the best ecommerce development platform. It’s powerful, secure, and cost-effective. Plus, it comes with a plethora of features and functionalities that are hard to find elsewhere for free.

If you want to build a feature-rich, secure, and scalable e-commerce store, contact us at +1 954-397-0800 for a consultation. We offer a wide range of nopCommerce development services tailored to your unique needs.