#oracle sql health check

[waterbeads1993]

SCL Health "The Landing": Empowering Health and Well-being

Introduction What is SCL Health “The Landing”? The Mission and Values of SCL Health Services Offered at “The Landing” Medical Services Mental Health and Counseling Services Addiction Treatment Wellness Programs The Approach to Care Patient-Centered Care Holistic Healing Integrative Medicine The Expert Team at “The Landing” Facilities and Amenities Insurance and Payment…

[rdbrng]

Strategic Database Solutions for Modern Business Needs

Today’s businesses rely on secure, fast, and scalable systems to manage data across distributed teams and environments. As demand for flexibility and 24/7 support increases, database administration services have become central to operational stability. These services go far beyond routine backups—they include performance tuning, capacity planning, recovery strategies, and compliance support.

Adopting Agile Support with Flexible Engagement Models

Companies under pressure to scale operations without adding internal overhead are increasingly turning to outsourced database administration. This approach provides round-the-clock monitoring, specialised expertise, and faster resolution times, all without the cost of hiring full-time staff. With database workloads becoming more complex, outsourced solutions help businesses keep pace with technology changes while controlling costs.

What Makes Outsourced Services So Effective

The benefit of using outsourced database administration services lies in having instant access to certified professionals who are trained across multiple platforms—whether Oracle, SQL Server, PostgreSQL, or cloud-native options. These experts can handle upgrades, patching, and diagnostics with precision, allowing internal teams to focus on core business activities instead of infrastructure maintenance.

Cost-Effective Performance Management at Scale

Companies looking to outsource dba roles often do so to reduce capital expenditure and increase operational efficiency. Outsourcing allows businesses to pay only for the resources they need, when they need them—without being tied to long-term contracts or dealing with the complexities of recruitment. This flexibility is especially valuable for businesses managing seasonal spikes or undergoing digital transformation projects.

Minimizing Downtime Through Proactive Monitoring

Modern database administration services go beyond traditional support models by offering real-time health checks, automatic alerts, and predictive performance analysis. These features help identify bottlenecks or security issues before they impact users. Proactive support allows organisations to meet service-level agreements (SLAs) and deliver consistent performance to customers and internal stakeholders.

How External Partners Fill Critical Skill Gaps

Working with experienced database administration outsourcing companies can close gaps in internal knowledge, especially when managing hybrid or multi-cloud environments. These companies typically have teams with varied technical certifications and deep domain experience, making them well-equipped to support both legacy systems and modern architecture. The result is stronger resilience and adaptability in managing database infrastructure.

Supporting Business Continuity with Professional Oversight

Efficient dba administration includes everything from setting up new environments to handling failover protocols and disaster recovery planning. With dedicated oversight, businesses can avoid unplanned outages and meet compliance requirements, even during migrations or platform upgrades. The focus on stability and scalability helps maintain operational continuity in high-demand settings.

[spectratechnologies-world]

Effective Oracle Server Maintenance: A Guide by Spectra Technologies Inc

Organizations in today's time rely heavily on robust database management systems to store, retrieve, and manage data efficiently. Oracle databases stand out due to their performance, reliability, and comprehensive features. However, maintaining these databases is crucial for ensuring optimal performance and minimizing downtime. At Spectra Technologies Inc., we understand the importance of effective Oracle server maintenance, and we are committed to providing organizations with the tools and strategies they need to succeed.

Importance of Regular Maintenance

Regular maintenance of Oracle servers is essential for several reasons:

Performance Optimization: Over time, databases can become cluttered with unnecessary data, leading to slower performance. Regular maintenance helps to optimize queries, improve response times, and ensure that resources are utilized efficiently.

2. Security: With the rise in cyber threats, Oracle server maintenance and maintaining the security of your oracle database is paramount. Regular updates and patches protect against vulnerabilities and ensure compliance with industry regulations.

3. Data Integrity: Regular checks and repairs help maintain the integrity of the data stored within the database. Corrupted data can lead to significant business losses and a tarnished reputation.

4. Backup and Recovery: Regular maintenance includes routine backups, which are vital for disaster recovery. Having a reliable backup strategy in place ensures that your data can be restored quickly in case of hardware failure or data loss.

5. Cost Efficiency: Proactive maintenance can help identify potential issues before they escalate into costly problems. By investing in regular upkeep, organizations can save money in the long run.

Key Maintenance Tasks

To ensure optimal performance of your Oracle server, several key maintenance tasks should be performed regularly:

1. Monitoring and Performance Tuning

Continuous monitoring of the database performance is crucial. Tools like Oracle Enterprise Manager can help track performance metrics and identify bottlenecks. Regularly analyzing query performance and executing SQL tuning can significantly enhance response times and overall efficiency.

2. Database Backup

Implement a robust backup strategy that includes full, incremental, and differential backups. Oracle Recovery Manager (RMAN) is a powerful tool that automates the backup and recovery process. Test your backup strategy regularly to ensure data can be restored quickly and accurately.

3. Patch Management

Stay updated with Oracle’s latest patches and updates. Regularly applying these patches helps close security vulnerabilities and improves system stability. Establish a patch management schedule to ensure that your database remains secure.

4. Data Purging

Regularly purging obsolete or unnecessary data can help maintain the database’s performance. Identify and remove old records that are no longer needed, and consider archiving historical data to improve access speed.

5. Index Maintenance

Indexes play a crucial role in speeding up query performance. Regularly monitor and rebuild fragmented indexes to ensure that your queries run as efficiently as possible. Automated tools can help manage indexing without manual intervention.

6. User Management

Regularly review user access rights and roles to ensure that only authorized personnel have access to sensitive data. Implementing strong user management practices helps enhance security and data integrity.

7. Health Checks

Conduct regular health checks of your Oracle database. This includes checking for corrupted files, validating data integrity, and ensuring that the system is operating within its capacity. Health checks can help preemptively identify issues before they become critical.

Conclusion

Oracle server maintenance is not just a technical necessity; it is a strategic approach to ensuring that your organization can operate smoothly and efficiently in a data-driven world. At Spectra Technologies Inc, we offer comprehensive Oracle database management services tailored to meet the unique needs of your organization. By partnering with us, you can rest assured that your Oracle server will remain secure, efficient, and resilient.

Investing in regular maintenance is investing in the future success of your business. Reach out to Spectra Technologies Inc. today to learn more about how we can help you optimize your Oracle database management and ensure seamless operations.

[uswanth123]

Oracle_Apex_Purge_Sessions

Understanding ORACLE_APEX_PURGE_SESSIONS: Your APEX Environment’s Housekeeping Job

Oracle Application Express (APEX) is a powerful low-code development platform that enables the rapid creation of web applications. However, like any busy web environment, APEX can accumulate inactive user sessions over time. This is where the background job ORACLE_APEX_PURGE_SESSIONS comes into the picture.

What is ORACLE_APEX_PURGE_SESSIONS?

ORACLE_APEX_PURGE_SESSIONS is a scheduled database job that automatically cleans up expired APEX sessions. Think of it as the housekeeper for your APEX workspace, keeping things clean and organized.

Why is it Important?

Performance Optimization: Inactive sessions occupy database resources like memory. Purging them regularly helps in maintaining the health and performance of your Oracle APEX environment.

Security: Expired sessions, if left unchecked, could increase vulnerability in some situations. ORACLE_APEX_PURGE_SESSIONS helps mitigate risks by removing inactive sessions.

Storage Management: APEX sessions involve data stored within the database. Purging old sessions ensures that database space is used efficiently.

How Does it Work?

The ORACLE_APEX_PURGE_SESSIONS job runs at a predefined interval (typically every hour). It does the following:

Identifies Expired Sessions: The job checks for APEX sessions that have been inactive for more than a certain period (usually 12 hours).

Purges Session Data: The job deletes the data associated with the expired sessions from relevant APEX tables (like WWV_FLOW_SESSIONS$).

Customizing the Job

While the default configuration of the job works for most cases, you might want to modify the frequency or the session expiration time limit based on your application’s requirements. Here’s how to adjust it:

SQL Workshop: Navigate to SQL Workshop within your Oracle APEX workspace.

Object Browser: Select “Object Browser” and search for the job “ORACLE_APEX_PURGE_SESSIONS” within the list of database objects.

Edit: Click the “Edit” option to make changes to the job’s schedule and other attributes.

Important Considerations

Before Tinkering: It’s recommended to understand the implications of modifying the job’s parameters. Always consult the Oracle APEX documentation before making significant adjustments.

Session Timeout in Applications: Ensure that the session timeout settings within your individual APEX applications align with the ORACLE_APEX_PURGE_SESSIONS’ purge timeline.

In Summary

ORACLE_APEX_PURGE_SESSIONS is an essential background process that contributes to a well-maintained and efficient Oracle APEX environment. Understanding its role is beneficial for any APEX developer or administrator.

You can find more information about  Oracle Apex in this  Oracle Apex Link

Conclusion:

Unogeeks is the No.1 IT Training Institute for Oracle Apex  Training. Anyone Disagree? Please drop in a comment

You can check out our other latest blogs on  Oracle Apex here – Oarcle Apex Blogs

You can check out our Best In Class Oracle Apex Details here – Oracle Apex Training

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[uswanth-123]

SAP Basis Operations

SAP Basis Operations: The Backbone of Your SAP Landscape

SAP systems are the central nervous system for many large enterprises. They streamline complex business processes, manage vast amounts of data, and drive critical decision-making. The technical foundation that keeps these systems running smoothly is known as SAP Basis.

What is SAP Basis?

SAP Basis is the heart of SAP administration. It’s a collection of middleware programs and tools that form the technological platform for SAP applications. Think of it like the operating system for your SAP environment. SAP Basis enables communication between different SAP modules, the underlying database, and the operating system itself.

Key Responsibilities of SAP Basis Operations

An SAP Basis team handles a wide array of crucial tasks. Let’s break them down:

Installation and Configuration: Setting up new SAP systems, configuring them for optimal performance, and tailoring them to the specific needs of the organization.

System Monitoring: Keeping a watchful eye on the health of SAP systems, proactively identifying potential bottlenecks or issues, and troubleshooting problems to ensure everything functions as intended.

Performance Optimization: Continuously analyzing and tweaking system parameters, database structures, and code to maintain peak performance of SAP applications.

User and Authorization Management: Creation of user accounts, assigning roles and permissions to ensure secure access to SAP systems while maintaining data integrity.

Transport Management: Overseeing the organized movement of code changes, configuration updates, and data between different SAP environments (e.g., development, testing, and production).

Backup and Recovery: Establishing robust backup strategies and recovery procedures to safeguard critical business data in case of system failures or disasters.

System Upgrades and Patches: Applying the latest SAP updates and security patches to maintain system stability, optimize performance, and address potential vulnerabilities.

Skills Essential for SAP Basis Professionals

A good SAP Basis administrator possesses a unique blend of technical knowledge and operational understanding:

Deep Understanding of SAP Architectures: Familiarity with various SAP landscapes, database systems (Oracle, SQL Server, HANA, etc.), and operating systems (Linux, Windows, etc.).

Troubleshooting Acumen: The ability to quickly diagnose and resolve technical problems, be it performance issues, system errors, or configuration conflicts.

Database Administration Skills: Expertise in database management, backup and recovery procedures, and performance tuning.

Security Awareness: Knowledge of security best practices, authorization concepts, and compliance requirements to safeguard SAP systems.

Communication and Collaboration: Since SAP systems interact with numerous departments, strong communication skills are needed for effective collaboration with developers, business users, and other IT teams.

Maintaining an Efficient SAP Landscape

SAP Basis operations involve a continuous cycle of monitoring, optimization, and proactive maintenance to ensure the smooth functioning of your SAP environment. By staying on top of system health, anticipating future needs, and swiftly resolving issues, SAP Basis teams play a pivotal role in the success of any enterprise running SAP applications.

You can find more information about SAP  BASIS  in this  SAP BASIS Link

 

Conclusion:

Unogeeks is the No.1 IT Training Institute for SAP  BASIS Training. Anyone Disagree? Please drop in a comment

You can check out our other latest blogs on  SAP  BASIS here – SAP BASIS Blogs

You can check out our Best In Class SAP BASIS Details here – SAP BASIS Training

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[sunalimerchant]

Extract Transform Load SQL

Extract, Transform, Load (ETL) is a fundamental process in data integration, enabling organizations to collect, process, and load data from various sources into a centralized data warehouse or target database. The first step in this process is the Extract phase, which involves retrieving data from heterogeneous sources such as databases, files, APIs, or web services. This article aims to provide a comprehensive understanding of the Extract phase in ETL using SQL and explore various tips and techniques to optimize ETL performance.

Understanding the Extract Phase in ETL with SQL:

The Extract phase in ETL is all about gathering data from source systems to prepare it for subsequent transformations and loading. SQL, which stands for Structured Query Language, plays a crucial role in the Extract phase as it allows users to interact with relational databases and efficiently retrieve data. The key steps in the Extract phase include:

Identifying Data Sources: The first step is to identify the data sources, which could be databases (e.g., SQL Server, Oracle, MySQL), flat files (e.g., CSV, Excel), web services, or APIs.

Writing SQL Queries: Once the data sources are identified, SQL queries are crafted to extract the relevant data. These queries can range from simple SELECT statements to complex joins and subqueries.

Data Filtering and Selection: SQL provides powerful capabilities for filtering and selecting specific data, allowing users to retrieve only the data needed for the ETL process.

Data Extraction Methods: Depending on the data sources, various methods can be employed for data extraction, such as full extraction (getting all data), incremental extraction (only new or modified data since the last extraction), or delta extraction (getting changed data within a specific time period).

Data Validation: During the Extract phase, data validation is essential to ensure data accuracy and integrity. SQL queries can be used to perform data quality checks and identify any discrepancies or errors in the extracted data.

Optimizing ETL Performance with SQL: Tips and Techniques:

Efficient ETL performance is crucial for timely data processing and maintaining the overall data pipeline's health. By optimizing the Extract phase with SQL, organizations can significantly improve ETL throughput and reduce processing times. Here are some valuable tips and techniques:

Use Indexed Columns: When querying large datasets, using indexed columns in the WHERE clause can significantly speed up data retrieval. Indexes facilitate faster data access by creating a reference to the data's physical location in the database.

Limit the Number of Columns: Specify only the necessary columns to be extracted in the SELECT statement. Extracting unnecessary columns consumes extra resources and may slow down the process.

Minimize Joins and Subqueries: Complex joins and subqueries can be resource-intensive. Where possible, optimize the SQL queries by minimizing joins and reducing subqueries to improve performance.

Filter Data at the Source: Whenever possible, filter data at the source before extraction. Pushing filtering logic to the source system reduces the amount of data transferred during extraction, enhancing performance.

Consider Parallelization: Parallel processing can significantly speed up the Extract phase. Consider using parallel queries or multi-threaded approaches to extract data simultaneously from multiple sources.

Use Incremental Extraction: For sources with large volumes of data, implement incremental extraction to only retrieve changed or new data since the last extraction. This reduces the data volume and shortens the extraction time.

Optimize Data Types: Choose appropriate data types for columns to minimize storage requirements and improve query performance.

Data Compression and Encryption: Use data compression and encryption techniques during data extraction to reduce data size and enhance data security.

Caching and Materialized Views: Consider caching frequently accessed data or using materialized views to store precomputed results for faster retrieval.

Regular Maintenance and Index Rebuilding: Perform regular maintenance tasks, such as index rebuilding and updating statistics, to ensure the database's performance remains optimal over time.

In conclusion, the Extract phase in ETL with SQL is a critical step in the data integration process. SQL provides powerful tools to efficiently retrieve data from various sources and ensure data accuracy during extraction. By applying the tips and techniques mentioned above, organizations can optimize ETL performance, reduce processing times, and create a robust foundation for subsequent Transform and Load phases. Efficient data extraction lays the groundwork for a successful ETL process, enabling organizations to make better data-driven decisions and extract valuable insights from their data.

[unispacebusiness]

Software Development Solution

Offshore Software Developer Billing Rates India - Offshore Software Development Hourly Rates  

Software development services are aimed at designing, engineering, deploying, supporting, and evolving various software types. Software development services is a complicated process to design an application or software in order to meet a particular business or personal objective, goal or process. This process consists of various stages: Planning, Analysis, Product Design, Development & Implementation, Testing, Maintenance.

Importance of Software Development : It is very important for businesses as it helps them distinguish from competitors and become more competitive.

Software development can improve the client's experiences, bring more feature-rich and innovative products to market, and make setups more safe, productive, and efficient.

Software development Services Provider in India : Owing to our immense knowledge, we are engrossed in offering a precision-engineered assortment of Software Development Service. Skilled professionals check these services on pre-defined quality parameters in order to fulfill the client requirement. Also, outsourcing is contracting with another person or company to do a particular function. Apart from this, these services are available to us at pocket-friendly prices within the committed span of time.

To Hire Consulting Services Today, Call UNIREVStech Nowmahendra@unirevstech.com UNIREVS tech : Technical Capabilities ✔Power BI ✔Tableau ✔QlikView ✔Qlik sense ✔Python ✔Big Data ✔Data Science ✔DevOps ✔RPA ✔.NET ✔JAVA ✔SQL Server ✔Oracle ✔Tera Data

Value Proposition24x7 and 365 days business operationsMore than 15 years of management team experienceUnique combination of technology with business process managementClient focused approach with implementation of important metrics such as TQM and Sig SigmaHigh level of automation in business operations to increase efficiency and productivity UNIREVS tech : Service and Solution Data Analytics Data Analytics Consulting Services & Solutions - Data Analytics Services Pricing - Data Analytics Services Companies For Hire In India Cloud and Platform Services  Cloud And Platform Services Provider - Cloud Computing Services Price In India

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Why Hire From India:India is Considered as a favorite destination for OFFSHORING. India still stand out in terms of size, breadth and quality of talent pool, cost of operations lower business risk and ability to scale up.

We Offers:Point of Contact for the Smooth Operations of Your Business. Management Support, Operational Support and Advisory

Contact Details Unirevs Technologies Private LimitedUnispace Business Center, Plot No#128/P2, EPIP Industrial Area Whitefield, Sonnenahalli Village, Bangalore, Karnataka-560048

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[sandeep2363]

Use of SQLHC SQL Health Check Script in Oracle

Use of SQLHC SQL Health Check Script in Oracle

Steps to use the SQLHC Script in Oracle 1. Download the SQLHC script from Oracle Support site with Document id: SQL Tuning Health-Check Script (SQLHC) (Doc ID 1366133.1) 2. Extract the SQLHC.zip folder to a suitable location. 3. Go to the location of the folder with the command prompt/terminal.In Windows, I unzip in D drive: D:\SQLHC. In the CMD window go to cd D:\SQLHC. 4. Start the SQLPLUS…

[bharathshan]

That’s a footing not only for your job search, however throughout your career. Interpret and visualize the results of simulation models to gauge advanced business choices in unsure settings. select the correct tool for decision-making to make future business methods and confirm the styles of predictions you'll make to make future methods. establish effective strategies for collecting knowledge on client behavior and use it to create higher choices for your business. Data analytics hasn't been my strongest ability therefore I'm glad to be exposed to a great deal of the latest thought and applications which will facilitate businesses to perform higher.

With knowledge at the guts of our economy and cyberattacks changing into additional frequent and severe, basic cybersecurity information is essential for today's personnel. learn the way everyday technology works, the way to operate firmly, and the way to strategically establish, evaluate, and answer security risks. once you take an ExcelR course, you are learning with a number of the highest within the trade.

Data Analytics Course

You will gain the flexibility to effectively produce knowledge visualizations, like charts or graphs, and can begin to check however they play a key role in human action your data analysis findings. All of this will be accomplished by learning the fundamentals of data analysis with surpassing and IBM Cognos Analytics, while not having to jot down any code. Throughout this course, you may encounter varied active labs and a final project.

Applicants are needed to disclose and supply tutorial transcripts for all coursework completed at the postsecondary level. the applier is taken into account a school transfer applier if they need to complete some or all of a college-level certification. estuary might use a mix of lychee and/or faculty courses and grades to see program eligibility.

A data person performs operations on the information provided to investigate and interpret it. It systematically ranks prime in international data science surveys and its widespread quality can solely keep it up increasing within the returning years. you'll notify 1st concerning the very best-rated digital courses and receive curated articles concerning digital education. employing a case-based approach, specific to the trade, the beneficiaries are going to be a part of problem-solving in an exceedingly real-world state of affairs. In this, your personnel can perceive the applying and scope of knowledge-connected technologies in your trade, be it BFSI, ITES, producing, telecommunications, Oil, and Gas, and so on.

On the course we've got chosen you may learn SQL which can change you to try to do some real data analysis. however, selling analytics and data analysis will go a lot deeper than that. By investing tools like conversation analytics solutions firms will gain deeper insights into client sentiment, improve regulative compliance, and improve omnichannel client expertise. The course then describes however you'll use insights from your knowledge sets to appear through your knowledge and realize fascinating trends and patterns.

It covers topics like data analysis, knowledge image, regression approaches, and supervised in-depth learning victimization of our applied learning model with industry-leading practitioners and project live sessions. This data analytics boot camp conjointly contains an intensive syllabus and offers dynamic learning expertise. there's beyond any doubt nice demand for data analytics as ninety-six of organizations request to rent Data Analysts. the foremost vital data analyst firms that use graduates World Health Organization would like to possess a data analyst career ar Manthan, SAP, Oracle, Accenture Analytics, Alteryx, Qlik, letter of the alphabet Analytics, form Analytics, and Tiger Analytics.

This Nano syllabus is enclosed with real-world comes and immersive content that's an inbuilt partnership with top-tier firms to assist you to master the school skills. throughout the program, you may get a one-on-one technical mentor, World Health Organization can assist you at each stage of learning. you may conjointly receive a private career coach and career services from the trainer to secure your career. you will gain skills in statistics, algorithms, machine learning, and image.

Typically, a student can have one 15-minute personal session every day, and this can be complemented by "scrum", the daily rise, and cluster code review expedited by the mentors. They conjointly lead radio-controlled discussions, or "spikes", around shared topics, like advanced issues that multiple students are performing on. you'll browse our students’ testimonials for an improved plan of Ubiqum’s results. Everything we tend to do is to assist you to begin your business life as a Data Analyst, net Developer, or Mobile Developer. "In this project, I got a concept of however Amazon net Services may be used to figure with an enormous quantity of knowledge ." Like Python, R may be a completely free ANd ASCII text file language and atmosphere that has become an accepted commonplace among data scientists thanks to its power and adaptability.

For More Details Contact Us ExcelR- Data Science, Data Analytics, Business Analyst Course Training Andheri Address: Shree Padmini Building, 301, Third Floor, Teli Galli Cross Rd, Sanpada Society, Andheri East, Mumbai, Maharashtra 400069, India Phone: 09108238354

Data Analytics Course

[bloghealth5656]

Best Budget Programming Laptop 2021 [Updated September] -

VIEW MORE CLICK BELOW

If you are thinking of buying a laptop for programming, but you are having difficulty choosing the most suitable laptop for you in the field of programming, design or games. All you have to do is read the article to learn about the most suitable laptops that may suit you in this field.

Thing you should check before buying any programming device!

Hard Disk: If you want to do programming it is better to consider getting a 256GB SSD, but you can also get great results from a standard 1TB drive. Speed   is critical. You will filter a large amount of energy through different logs and folders.

RAM: For developers, RAM is like water. The standard RAM limit for a general laptop is around 4GB. Usually this configuration is sufficient for basic tasks. In any case, for software engineers, it is recommended to purchase a laptop with at least 8 GB of RAM. In a perfect world, having 16GB of RAM should be a top priority for you. This will cost more, but the maximum memory will be quite useful.

Processing speed: The most important thing to spend with processing power is compilation time. In any case, you should have a machine that coordinates your goal as expected, but in a way that fits your goal. Laptops with i5 or i7 processors are the best for programming in 2019.

Repairability: If you need to add RAM or replace the hard drive with a larger one? If you realize that you need to add more power to your laptop over the next year or two, repairability is an important factor. Not all laptops allow it to do this. Some of these devices (such as the Macbook) are made in such a way that it is almost impossible to replace a hard drive or RAM.

A short note before you begin

Computer programming is not about algorithms, flowcharts and codes, one needs to understand them from their hardware. It is really important to write codes and solve problems with the perfect laptop. The best way to get ahead in the world of programming is to make sure you have the best laptop to help you realize your ideas. In short, the ideal laptop speeds up tasks and processes that help increase productivity. To find the perfect laptop, you need to know what to look for.

1. Apple MacBook Pro MF839LL

📷

The Apple MacBook Pro has a 2.7GHz Intel Core i5 processor. The best thing about this laptop is that it has 128GB of PCIE flash storage, 8GB of DDR3L RAM with Intel Iris graphics and a 13.3-inch IPS Retina display.

Screen size 13.3 inch IPS Retina display.

Screen Resolution 2500 x 1600

Max screen resolution 1366 x 768

Processor 2.7 GHz Intel Core i5

Data storage 8 GB LPDDR3 RAM

Memory Speed   1866MHz

Key Features of Apple MacBook:

Battery performance is excellent. It contains a non-removable Li-Polymer battery for 10 hours during the charging period.

The processing power is amazing. It is best for programmers who want to work on different technologies such as Oracle and Microsoft SQL Server. It can run Windows and Linux VMs quickly and the performance is excellent.

Retina MBP is durable and ideal for programmers working as web designers and developers.

It can handle large documents. The new Thunderbolt technology gives programmers the opportunity to quickly connect to other devices at a data transfer rate of 10 Gbps. It can also run APIs like Python and Visual Studio C# without any problems. The best Apple laptop for programming.

[avantaglobal]

Data Analytics using Tableau Course

What is Tableau?

Tableau may be a powerful and quickest growing knowledge image tool utilized in the Business Intelligence business. It helps in simplifying information during a very simply perceivable format. Tableau helps produce the info which will be understood by professionals at any level in a company. It additionally permits non-technical users to make custom-built dashboards.

Data analysis is incredibly quick with Tableau tool and also the visualizations created are within the style of dashboards and worksheets.

The best features of Tableau software are

Data Blending

Real time analysis

Collaboration of data

The great factor concerning Tableau computer code is that it doesn’t need any technical or any reasonably programming skills to control. The tool has garnered interest among the individuals from all sectors like business, researchers, completely different industries, etc.

In this article, you'll learn-

·         What is Tableau?        

·         Tableau product suite

·         Tableau Desktop

·         Tableau Public

·         Tableau Server

·         Tableau Online

·         Tableau Reader

·         How does Tableau work?

·         Tableau Uses

·         Excel Vs. Tableau

 Tableau Product Suite

The Tableau Product Suite consists of:

·         Tableau Desktop

·         Tableau Public

·         Tableau on-line

·         Tableau Server

·         Tableau Reader

For a transparent understanding, knowledge analytics in Tableau tool may be classified into 2 sections.

Developer Tools: The Tableau tools that are used for development like the creation of dashboards, charts, report generation, image make up this class. The Tableau merchandise, below this class, are the Tableau Desktop and also the Tableau Public.

Sharing Tools: because the name suggests, the aim of those Tableau merchandise is sharing the visualizations, reports, dashboards that were created mistreatment the developer tools. merchandise that makes up this class are Tableau on-line, Server, and Reader.

Let’s study all the Tableau merchandise one by one.

·         Tableau Desktop

Tableau Desktop encompasses a wealthy feature set and permits you to code and customise reports. Right from making the charts, reports, to mixing all along to create a dashboard, all the required work is formed in Tableau Desktop.

For live knowledge analysis, Tableau Desktop provides property to knowledge Warehouse, also as alternative varied forms of files. The workbooks and also the dashboards created here may be either shared regionally or in public.

Based on the property to the info sources and publication possibility, Tableau Desktop is assessed into

Tableau Desktop Personal: the event options are almost like Tableau Desktop. Personal version keeps the book non-public, and also the access is proscribed. The workbooks can't be printed on-line. Therefore, it ought to be distributed either Offline or in Tableau Public.

Tableau Desktop Professional: it's just about almost like Tableau Desktop. The distinction is that the work created within the Tableau Desktop may be printed on-line or in Tableau Server. Also, in skilled version, there's full access to any or all kinds of the datatype. it's best appropriate for people who would like to publish their add Tableau Server.

·         Tableau Public

It is Tableau version specially build for the cost-efficient users. By the word “Public,” it means the workbooks created can't be saved locally; successively, it ought to be saved to the Tableau’s public cloud which may be viewed and accessed by anyone.

There is no privacy to the files saved to the cloud since anyone will transfer and access an equivalent. This version is that the best for the people World Health Organization need to be told Tableau and for those World Health Organization need to share their knowledge with the final public.

·         Tableau Server

The computer code is specifically accustomed share the workbooks, visualizations that ar created within the Tableau Desktop application across the organization. To share dashboards within the Tableau Server, you need to initial publish you add the Tableau Desktop. Once the work has been uploaded to the server, it'll be accessible solely to the accredited users.

However, it’s not necessary that the accredited users have to be compelled to have the Tableau Server put in on their machine. they solely need the login credentials with that they will check reports via an internet browser. the safety is high in Tableau server, and it's abundant suited to fast and effective sharing of information in a company.

The admin of the organization can invariably have full management over the server. The hardware and also the computer code are maintained by the organization.

  ·         Tableau on-line

As the name suggests, it's an internet sharing tool of Tableau. Its functionalities are almost like Tableau Server; however, the info is kept on servers hosted within the cloud that are maintained by the Tableau cluster.

There is no storage limit on the info which will be printed within the Tableau on-line. Tableau on-line creates a right away link to over forty knowledge sources that are hosted within the cloud like the MySQL, Hive, Amazon Aurora, Spark SQL and plenty of a lot of.

To publish, each Tableau on-line and Server need the workbooks created by Tableau Desktop. knowledge that's streamed from the net applications say Google Analytics, Salesforce.com are supported by Tableau Server and Tableau on-line.

·         Tableau Reader

Tableau Reader may be a free tool that permits you to look at the workbooks and visualizations created mistreatment Tableau Desktop or Tableau Public. the info may be filtered however redaction and modifications are restricted. the safety level is zero in Tableau Reader as anyone World Health Organization gets the book will read it mistreatment Tableau Reader.

If you wish to share the dashboards that you simply have created, the receiver ought to have Tableau Reader to look at the document.

How will Tableau work?

Tableau connects and extracts the info keep in varied places. It will pull knowledge from any platform thinkable. a straightforward info like AN surpass, pdf, to a posh info like Oracle, a info within the cloud like Amazon webs services, Microsoft Azure SQL info, Google Cloud SQL and varied alternative knowledge sources may be extracted by Tableau.

When Tableau is launched, prepared knowledge connectors are on the market that permits you to attach to any info. looking on the version of Tableau that you simply have purchased the amount of information connectors supported by Tableau can vary.

The force knowledge may be either connected live or extracted to the Tableau’s knowledge engine, Tableau Desktop. this can be wherever the info analyst, knowledge engineer work with the info that was force up and develop visualizations. The created dashboards are shared with the users as a static file. The users World Health Organization receive the dashboards views the file mistreatment Tableau Reader.

The data from the Tableau Desktop may be printed to the Tableau server. this can be AN enterprise platform wherever collaboration, distribution, governance, security model, automation options are supported. With the Tableau server, the top users have an improved expertise in accessing the files from all locations be it a desktop, mobile or email.

Tableau Uses

Following are the most uses and applications of Tableau:

Business Intelligence

Data Visualization

Data Collaboration

Data Blending

Real-time data analysis

Query translation into visualization

To import large size of data

To create no-code data queries

To manage large size metadata

Excel Vs. Tableau

Both surpass and Tableau are knowledge analysis tools, however every tool has its distinctive approach to knowledge exploration. However, the analysis in Tableau is more impregnable than surpass.

Excel works with rows and columns in spreadsheets whereas Tableau permits in exploring surpass knowledge mistreatment its drag and drop feature. Tableau formats the info in Graphs, photos that are simply perceivable.

Tableau beats surpass in major areas just like the interactive dashboards, visualizations, capabilities to figure with large-scale knowledge and plenty of a lot of.

[entitledunemployedmillennial]

WIOA Failure

Around 2018, my parents found out about WIOA through the Prince George's branch of the American Job Center and told me about the WIOA program at the Prince Georges County job center. The WIOA stands for Workforce Innovation and Opportunity Act. It’s a law that allows states and counties to support unemployed Americans with federal funds for retraining via a private training center or community college or have paid on-the-job training from local employers working with the American Job Center, with the possibility of being picked up by the company for a full-time role. You can’t pick both options so it really depends on what you need.

Obviously, because I have no savings and my unemployment slowly running out, I had to take the paid on-the-job training. So I called the Job Center and expressed my interested in the WIOA program. And you have to express interest in it because this program is not well-advertised to the unemployed.

But I heard about WIOA from my parents who had the opportunity to get a job via their on-the-job training program but could not because they had health issues. But WIOA is known as the Work Investment and Opportunity Act. The allow allows grants for study for certs or classes or for on-the-job training. I opted for the on-the-job training because I needed the money and two there was the possibility for the company to pick me up.

After I made the appointment, and went to the appointment in the office, the co-ordinator which was a woman explains the entire process.The entire process but the actual process will not start until I fill out several forms. You have to fulfill a checklist of requirements to be approved for the program, then verify the fact that you’re a displaced worker or unemployed. In that form you have to explain why you’re having difficulty seeking work. I’ve explained in full honesty that I have autism spectrum disorder which makes it difficult to gain relationships in order to seek better work, gaining relationships with co-workers is practically the only way to gain employment, and difficulty seeking security clearances because I’ve been the sole provider of my parents for 4 years because they were unemployed.

Then you have do actual research on the job you want via a occupational research assignment. Doing that assignment is very difficult because in most companies you want to interview with, the HR departments are difficult to contact by phone or email. But what I had to do was print out three job openings that had the job title I want, and fill in the required information the best i can.

And, of course, you need to submit your resume.

After you submit the information by email or in person. You have to go to a orientation course that tells you everything about the WIOA, what the Act is, how does it work and the details about the options they provide. It was the same co-ordinator that handled my paperwork. From what I heard from her regarding being placed to a paid on-the-job training position that it takes from 2 weeks to 6 months, but on average it takes three months to be placed in one of those to start work. She knew how dire my situation is since I dropped hints on it.

Finally after the orientation class, you have to take a Prove-IT test. Now for that test, I was able to take the System Administration test, but the Oracle Java exams and SQL exams were very difficult to take because I had no knowledge of them and it was a surprise for me because I did not expect such a test.

All I could do was to guess the answers the best I could in order to complete the remaining exam.

Then finally, another co-ordinator which was another woman gave me a link to the System Administrator job for a local contractor for the Prince Georges county government. The job would be a great fit for me if I was actually hired. Then I encountered the same problems with dealing with third-party IT recruiters, but it’s worse since you’re dealing with the state government since if they screw up, they don’t get easily disciplined or fired unlike the private sector.

I did the same thing as I did to the IT recruiters. I followed up with them by phone every week to make sure I exist and to check up on the hiring process. Often times, I leave a voicemail message and I don’t get a return call back. Often times I had to do a weekly follow up on both co-ordinators. Each one told me that they will update me tomorrow or the next day. When tomorrow or the next day came and I don’t get a phone call back, and I had to be the one calling them back.

Then slowly, I found reasons why it took so long to hear anything back from the person who gave me that job link from the other co-ordinator: The first excuse: She went on vacation. The second excuse was that she got married after she went on vacation. Finally I was told that her office was being moved to a different location. Despite all of this, she could not take 30 minutes of her time following up on voice mail messages in between the times she went on vacation and marriage.

Finally, they admitted months later that the position I have applied to with the company that was supposed to work with the American Job Center with unemployed Americans who signed up with the WIOA was closed. Worse, basically told me that they threw their hands up instead of actually giving me a position that they would have worked with ASAP by telling me to go to a IT recruiter. The same IT recruiters that I contacted a week after I was laid off that months later threw their hands up and told me they actually have nothing for me after wasting 2 hours of time talking to them at their office and doing weekly follow ups over the phone.

Even the Government of the State of Maryland does not value the time or skills of the unemployed. Even if the unemployed person is disabled and has a autism spectrum disorder.

[uswanth-123]

SAP Basis Modules List

Understanding SAP Basis: The Essential Modules for System Administration

SAP Basis is the technical foundation that powers all SAP systems. It’s a collection of modules and components that act as the backbone, handling system administration, monitoring, and essential infrastructure tasks. If you’re managing an SAP environment, familiarizing yourself with SAP Basis modules is crucial.

What is SAP Basis?

Operating System and Database Management: SAP Basis ensures seamless interaction between SAP applications and the underlying operating system (like Windows, Linux, etc.) and databases (Oracle, SQL Server, etc.)

Middleware: It provides the communication layer for different SAP components to interact smoothly.

System Monitoring: Tools within Basis allow for proactive monitoring of SAP system health, identifying potential issues, and maintaining performance.

User Administration: Basis manages user accounts, security roles, and authorizations within the SAP environment.

Transport Management: Coordinates the movement of development objects, configurations, and code changes across different SAP landscapes (development, testing, production).

Key SAP Basis Modules

SAP NetWeaver: The core technical platform that underpins all SAP systems. It includes the following:

ABAP Workbench: The development environment for creating custom code in SAP’s proprietary language, ABAP.

Java Stack: Supports applications built in Java and runs alongside the ABAP stack.

SAP Solution Manager: A centralized platform for system management, monitoring, implementation, and support of SAP landscapes.

SAP GUI: The graphical user interface that provides users access to SAP applications.

System Administration and Monitoring Tools: This suite of tools offers extensive monitoring, troubleshooting, and configuration capabilities for the SAP Basis administrator.

Why is Understanding SAP Basis Important?

For any organization running SAP, Basis expertise is non-negotiable. SAP Basis administrators ensure:

System Stability: Optimal system performance and availability through proactive maintenance.

Security: Maintaining a secure SAP environment through user management, authorization controls, and security patches.

Problem Resolution: Efficient troubleshooting and resolution of technical issues that arise.

Change Management: Seamless implementation of software upgrades, patches, and configuration changes.

Wrapping Up

SAP Basis is extensive and complex. This blog provides a high-level overview of its critical modules and the important role it plays within an SAP ecosystem. Whether you are a seasoned SAP administrator or new to this area, continuous learning and exploring the various facets of SAP Basis is essential for the successful operation of your SAP landscape.

You can find more information about SAP  BASIS  in this  SAP BASIS Link

 

Conclusion:

Unogeeks is the No.1 IT Training Institute for SAP  BASIS Training. Anyone Disagree? Please drop in a comment

You can check out our other latest blogs on  SAP  BASIS here – SAP BASIS Blogs

You can check out our Best In Class SAP BASIS Details here – SAP BASIS Training

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[pignose-barn]

데이터(Data)와 분석(Analysis)에는 어떤 일이 벌어지고 있느뇨?

오랜만에 블로그 포스팅을 하는 것 같습니다. 오래전에 쓴 영양가 없는 글들도 많이 정리해서 이번에 새로운 컨텐츠 들을 많이 채워보겠습니다.

이번 블로그 주제는 데이터(Data)와 분석(Analysis)인데요 많은 분들이 관심가지고 있고 또 앞으로도 한동안은 이 스코프에 있는 산업군은 근심걱정이 없기도 해서 많은 주니어분들과 타 직종에 계신분들이 자주 관심가지고 보실 것 같습니다.

들어가기 앞서

이 글에서는 빅데이터에 대해서 거론하지 않습니다.

이 글에서는 데이터 사이언스 기술에 대해서 거론하지 않습니다.

이 글의 작성자는 전문가가 아닙니다.

들어가며

서비스 개발에 종사하시는 많은 부류의 개발자 분들은 대부분 데이터베이스(Database)라는 것을 들어보셨을 겁니다. 보통 서비스에 있는 동적 데이터와 사용자의 상태를 세션(Session)으로 관리하되 이를 스토어(Store)로 연결하고자 데이터베이스를 서비스와 연결하여 사용하는 것이 일반적이지요.

여러분이 많이 들어보신 MySQL, MSSQL, Oracle, DB2, CosmosDB, PostgreSQL, MariaDB 등이 이러한 관계형 데이터베이스(RDBMS)가 되겠습니다.

<그림 1.1 여러분이 사랑해주시는 우리의 MySQL 찡...>

참고로 여기서 MySQL을 “마이에스큐엘” 이라고 발음하시는 분들이 많으신데요 현업에서는 “마이시퀄"이라고 부르는 경우가 많습니다. PostgreSQL 또한 “포스트그레스큐엘”이 아닌 “포스트그레스퀄"이라고 부르는 경우가 많습니다.

보통 우리는 서비스단에 이러한 RDBMS를 연결할 때, RDBMS가 있는 부분을 지속 레이어 혹은 퍼시스턴스 레이어(Persistence Layer)라 부릅니다.

<그림 1.2 서비스에서 구분되는 계층들>

물론 서비스 단에서 DB를 사용할 때는 데이터 무결성(데이터과 일관적이고 정확함을 보증)해야 하고 또 만약 데이터 처리에 문제가 생겨도 이를 대처할 수 있어야합니다. (*폴트톨러런스) 위의 것들을 지원하기 위한 목적을 가진 데이터베이스를 일반적으로 우리는 OLTP (Online transaction processing) 라고 부릅니다.

위 설명이 다소 복잡할 수 있어서 아래에서는 사례를 하나 들어드려 보겠습니다. 여러분이 만약 여행사 API를 이용하여 사용자가 돈을 결제하면 여행사 등록을 하는 시스템을 만들어보겠습니다. 서비스 프로세스에서 처리할 것은 아래와 같습니다.

사용자가 특정 여행사에 신청을 넣고 크레딧을 사용

서버에서 여행사 API에 접근하여 정원 초과여부, 사용자 등록정보를 바탕으로 유효성 체크등을 거쳐 올바를 경우 다음 단계 진행

사용자의 크레딧 DB에 요금이 있는지 확인

사용자의 크레딧 DB에서 크레딧을 차감 (DB 작업)

여행사 API에 접근하여 예약 처리

예약이 성공적으로 성사 됨을 사용자에게 알림

 위 시나리오대로 구현 하면 일반적인 경우에는 서버의 장애는 발견되지 않는다고 생각할 수 있을 텐데 여기에는 심각한 문제들이 여럿 있습니다. 아래는 여기서 발생할 수 있는 장애 시나리오를 간단하게 나열해봤습니다.

여행사 API에서 에러를 보내는 경우 (a. 여행사 서버 문제, b. 유효성 검증 이후 잠깐의 처리시간동안 다른 사용자가 예약을 진행한 경우 등)

사용자가 동시적인 예약처리로 인해 크레딧 체크 이후 크레딧이 줄었을 경우

서버의 장애로 인해 예약처리를 수행하지 못했을 경우 (서버의 재배포, 서버의 다운 등)

세상은 항상 논리적이고 완벽하지 않기 때문에 우리는 이런 의도치 않은 사항을 예방해야 합니다. 다행스럽게도 우리에게는 트랜잭션(Transaction)이 있기에 위의 문제를 아름답게 해결 할 수 있습니다.

<그림 1.3 트랜잭션의 방식에 대한 그림>

트랜잭션의 원리는 비교적 간단합니다.

트랜잭션 컨텍스트를 정의하고 (Begin transaction 혹은 savepoint) 그 컨텍스트 안에 있는 처리들을 마지막에 반영(Commit)하거나 취소(Rollback) 하실 수 있습니다. Auto Commit이 설정되있지 않으면 서버에서 피치 못하게 처리 응답을 못할 경우 데드맨스위치와 유사하게 자동으로 취소(Rollback)합니다.

우리는 아까의 시나리오를 트랜잭션을 이용하여 아래처럼 처리 할 수 있습니다.

사용자가 특정 여행사에 신청을 넣고 크레딧을 사용

서버에서 여행사 API에 접근하여 정원 초과여부, 사용자 등록정보를 바탕으로 유효성 체크등을 거쳐 올바를 경우 다음 단계 진행

트랜잭션 시작

사용자의 크레딧 DB에 요금이 있는지 확인

사용자의 크레딧 DB에서 크레딧을 차감 (DB 작업)

여행사 API에 접근하여 예약 처리

만약 이 과정중 어떤 에러라도 있다면 트랜잭션 취소(Rollback)

트랜잭션 종료 및 반영(Commit)

예약이 성공적으로 성사 됨을 사용자에게 알림

물론 위의 시나리오에서도 사용자가 동시적으로 크레딧을 결제할 경우는 막을 수 없습니다.

이를테면 동시간대에 2개 이상의 트랜잭션이 동시에 작동하여, 5만원의 크레딧 중 한곳은 5만원을 사용하고 또 한곳은 3만원을 사용하여 둘중 하나는 취소되어야 함에도 불구하고 두 처리 모두 조회단계에서 5만원이 조회되고 처리 단계는 그 이후 수행되기에 총 8만원이 소진되는 현상 (이때도 둘 중 어떤 트랜잭션이 먼저 실행되었냐에 따라 잔금이 2만원이 남아버리기도 하는 엄청난 사태)

이를 완벽하게 처리하고자 한다면 비관적 동시성 제어 처리를 위해 읽기 락을 걸거나 다중 체크를 통해 결제를 보장해야 합니다. 일단 이 설명은 모두와 나를 위해 생략합니다!

우리는 한때 RDBMS와 트랜잭션만을 이용해서도 서비스 제공하기에는 큰 지장이 없었습니다. (물론 확장성과 가용성은 여기서 빼도록 합시다!)

여기까지 읽으셨다면 아래 문서도 같이 살펴보세요

관계 - 데이터베이스 (위키피디아)

DBMS는 어떻게 트랜잭션을 관리할까? (Naver D2)

OLTP와 OLAP (devkingsejong's dev life)

클라우드 환경에서 새로운 ACID, BASE 그리고 CAP (미물의 개발 세상)

커넥션 풀 (Connection Pool)

커넥션 풀 (Connection Pool - DBCP) 없이는 당장에는 서비스 테스트에 큰 문제가 없겠지만 서비스를 런칭하고 유저가 다수 붙으면 차차 문제가 발생하기 시작합니다.

데이터베이스를 모니터링 해보면 Current 커넥션은 요동치기 시작하며 데이터베이스는 불필요한 CPU Latency를 가지게 됩니다.  여러분의 서비스는 홈페이지 처음 입장 시 DB에서 사용자 세션 정보를 가지고오고 (이를테면 메모리 스토리지에서), 추가적으로 메인 페이지의 최신뉴스를 DB에서 가져온다고 치자면 여러분은 DB에 2개의 쿼리 요청(트랜잭션)을 시도하게 됩니다.

유저의 세션 정보 조회 쿼리

최신 뉴스를 가져오는 쿼리

보통 유저의 세션 정보를 가져오는 처리와 최신 뉴스를 가져오는 처리는 기능상으로 분리되기 때문에 서로 다른 DB 커넥션이 발생하게 되는데 이를 그림으로 표현하면 아래와 같습니다.

<그림 2.1 유저 별 트랜잭션 별 쿼리 생성>

문제는 각 요청 별로 DB에 커넥션을 새로 얻어와서 (그림상의 빨간부분) 쿼리를 진행하는데 커넥션을 얻어오는 과정이 오래걸리기 때문에 사용자는 그동안 대기하게 되며 또 이러한 처리는 DB 서버에 있어서도 어느정도 CPU 연산이 필요하기에 전체적으로 비효율적으로 작업이 돌아가게 됩니다.

<그림 2.2 커넥션 풀의 관리>

위의 그림처럼 커넥션 풀을 이용할 경우 서버가 초기에 커넥션을 커넥션 풀에 설정된 용량 (Max connection)만큼 연결해놓고 사용자가 실제로 트랜잭션을 진행 할 때는 이렇게 미리 연결된 커넥션을 잠시 빌려 사용하고 돌려주는(Release) 하는 방식으로 돌아가기 때문에 실제로 DB에는 커넥션이 안정적으로 유지되고 또 CPU 부하가 줄어들게 됩니다.

커넥션 풀에 대한 정보를 모아봤습니다!

DB Connection Pool에 대한 이야기 (안녕 프로그래밍)

Commons DBCP 이해하기 (Naver D2)

확장성 그리고 고 가용성

여러분이 신입에서 조금씩 걸어 올라오다 보면 서비스를 준비하는 단계에서 무결성(일관성과 정확성, 원자성 등) 다음으로 확장성과 가용성이 굉장히 중요한 요소인 것을 점차 느끼게 되는데 둘에 대한 간략한 설명은 아래와 같습니다.

확장성(Scalability): 사용자가 많아지고(커넥션, 트랜잭션 증가) 처리해야 할 데이터의 양이 많아 지면서(인덱스 증가, 카디널리티 증가, 스캔용량 증가) 물리적인 서버의 성능을 향상 스킬 수 있는 능력이나 방법.

가용성(Availability): 주어진 환경에서 어떠한 문제(서비스의 장애) 없이 유지시킬 수 있는가에 대한 정도. (i.e 가동률)

만약 여러분이 서비스를 잘 만들고 라이브 서비스로 오픈 했는데 하루만에 DB 서버가 뻗고 (일반적인 장애 혹은 스팩 자체의 문제) 이를 복구하는데도 수시간이 걸린다면 가용성이 심각한 문제가 있는 것이게 됩니다. 또한 서비스의 성능이 느려 이를 개선하는데에 있어 시간적 비용이나 공간적 비용(서버공간 추가, 서버 이전), 인적비용(마이그레이션 담당자 투입, DBA 투입, 서버엔지니어 투입)이 발생한다면 확장성이 낮은 것이지요.

DBMS 종류마다 이러한 가용성, 확장성을 SW 레벨에서 지원하기 위한 기능도 있으며 이런 차이 때문에 많은 데이터 관련 엔지니어나 종사자들이 많은 공부�� 하고 있습니다.

확장성을 깊게 들여다보며

<그림 3.1 확장성에 대한 간단한 그림 (scale-out 측면)>

아까는 확장성에 대해 간단하게만 서술 했는데 이번에는 조금 더 깊이있게 얘기해 보겠습니다. 데이터베이스 서버가 느려 이를 확장하는 경우 간단하게 두개로 나뉘게 됩니다.

SW 레벨에서의 확장 (논리적인 확장)

HW 레벨에서의 확장 (물리적인 확장)

당연하게도 HW쪽이 비용과 시간은 더 많이 소모되겠죠.

SW 레벨에서의 확장을 하는 케이스 사실 확장이라 칭하기보다 최적화가 더 맞는 말일 듯 합니다. 보통 로그테이블이 많이 쌓여서 로우가 추가될 때마다 인덱싱도 느리고 또 서치를 해도 불필요하게 스캔 코스트가 많이 들기 때문에 테이블 파티셔닝을 하게 됩니다.

HW 레벨에서의 확장은 경우의 수가 많습니다만 크게 아래와 같이 또 한번 분류 할 수 있습니다.

수직 확장의 측면(Scale-up)

수평 확장의 측면(Scale-out)

<그림 3.2 수직확장(scale-up)과 수평확장(scale-out)에 대한 설명>

수직 확장은 쉽게 얘기하여 서버 자체의 성능을 늘리거나 처리 방식을 개선하여 알고리즘을 효율적으로 돌아가게 하는 등으로 개선이 필요한 인스턴스 자체를 조정하는 것이라 보면 됩니다.

수평 확장은 그와 다르게 서버의 수를 늘려 분산을 하거나 스캔 대상의 파일을 쪼개어 분산하거나 혹은 연산 프로세싱 만을 분산하는 등 하나의 커다란 문제를 쪼개어 해결하는 것으로 초점이 맞춰져 있습니다.

수직 확장의 경우에는 보통 서버의 스팩을 올리거나, 랜 공사를 해서 데이터 서버가 사용하는 랜 성능을 키운다거나 디스크를 증설하여 저장공간을 키우는 형태로 보통 서버가 정지됩니다.

수평 확장은 클러스터를 구성하여 서버 노드를 늘리거나, 디스크 노드를 늘리거나 마이크로 서버를 띄워 프로세싱을 맡기는 등의 처리를 통하여 성능을 늘리며 보통 이런 처리가 무정지로 이루어지거나 Write Lock만을 통하여 진행합니다.

확장성의 경우 이렇다 저렇다 얘기가 많지만 주관적으로 수평확장이 수직확장에 비해 안전하고 요금 측면에서 효율적이며 각종 위험에 대하여 안전합니다. (Fail-over, Multi region)

수평 확장을 통하여 데이터를 분산 할 경우 샤딩(Sharding 혹은 Horizontal Partitioning)을 하게 되는데 이를 통해 데이터의 저장소를 분배하고 실제로 데이터를 수집하고 집계 할 때,  리더 역할을 하는 컴퓨터에 조회 요청을 보내고 리더 컴퓨터에서 분산된(샤딩된) 데이터를 각각의 목적 노드에서 추출하고 집계하여 반환하게 됩니다. 물론 이런 리더-컴퓨터 구성처럼 미들티어(Middle-tier) 형태로 작동하는 것도 있지만 Hibernate Shards와 같이 어플리케이션 레벨에서 동작하는 경우도 있으며 이마저도 아닌 데이터베이스 자체에서 지원하는 케이스도 있습니다.

<그림 3.3 파티셔닝에 대한 간단한 설명 그림>

가용성을 깊게 살펴보며

이번에는 아까 말씀드린 가용성을 깊게 살펴봅시다.

가용성은 다시말해 “서버가 얼마나 안정적으로 오랫동안 운영되고 있나"를 알려주는 성질입니다. 서버가 정지되는 시간(다운타임)을 최소화 하는 것이 궁극적으로 고 가용성을 제공하는 방법입니다.

수직 확장의 경우에는 이런 처리가 다소 난해한 요소로 자리 잡고 있습니다. 서버 자체가 문제가 발생 할 때 이를 대체 해 줄 수 있는 서버가 존재하지 않으면 마땅한 방법이 없기 때문인데 이 때문에 별도의 모니터링이나 대리자(Proxy)를 두게 됩니다.

수직 확장의 경우에도 데이터 디스크와 데이터서버를 분리하고 데이터서버 앞에 로드밸런서를 붙여 상태검사(Health Check)이후 문제가 발생하면 후차 데이터베이스 (Secondary or Slave or Stand by)를 활성화(Idle, Promote to master)하여 자동으로 정상화 합니다. 이렇다 하더라도 데이터센터가 지역적으로 한곳에 있다면 천재지변이 발생할 경우 서비스는 다운됩니다.

후후.. 이제 조금만 더 읽으면 끝납니다! 복습 차원에서 아래 관령 링크를 살펴보세요!

분산 데이터베이스와 성능 (DBGuide)

NHN의 안과 밖: Sharding Platform (Naver D2)

DFS: Not a Distributed Database

어떤 분산 파일 시스템을 사용해야 하는가? (Naver D2)

클러스터와 리플리케이션의 차이가 뭔가요?

<그림 4.1 slave 관점에서의 failover 예시>

Fail-over 전략에 대해서도 워낙 다양하기에 여기서 모든 것을 설명 드릴 수는 없고, 기회가 되면 추가 포스팅을 하고 링크를 이곳에 연결해드리겠습니다.

조금 특이한 fail-over 전략으로는 데드맨 스위치(Deadman switch)가 있습니다. 전략이라기 보다는 일반적인 fail-over가 이에 근거하여 돌아간다라고 설명드릴 수 있을 것 같은데요 DB 앞에 Load Balencer가 붙어 이상점을 감지하여 레플리카를 대체하건 M-M 구성에서 Master의 이상점을 감지하여 승격과정을 거치건 둘 이상의 노드간에 약속된 패킷과 발송 시간을 정하여 그것이 도착하지 않으면 이상으로 감지하여 데드맨 스위치가 켜지는 방식입니다.

퍼포먼스

서비스의 안정성이 가장 중요하지만 두번째로 중요한 것은 성능입니다. 사용자는 점점 즉각적이고 신속한 응답을 바라고 있고 우리는 더 많은 양의 정보를 바탕으로 질 높은 정보 얻어 다른 업체와 경쟁해야 합니다.

퍼포먼스(Performance)를 향상시키는 전략도 여러가지가 있습니다.

일반적으로는 Explain과 slow query 로그 분석을 통해 쿼리 플랜을 최적화 하는 것이 있으며 이는 많은 비용이 들지도 않습니다. 물론 이것도 방법론이 많습니다. (커버링 인덱스를 사용하거나 컬럼 자체의 인덱스를 관리하는 관점, recency score를 두거나 등)

두번째는 튜닝(Tuning)이 있습니다. 너무 당연하겠지만 제일 효율적인 성능을 위해서는 서비스에 특성이 맞게 DB가 세팅되고 돌아가야 합니다. 서비스에 맞게 스토리지 엔진 타입을 바꾸거나 인덱스를 새롭게 설정하거나 인덱스 알고리즘을 바꾸거나, 압축 방식을 바꾸거나 버퍼 캐시를 수정하는 등의 방법이 있습니다.

세번째는 서비스 분산 아키텍처를 설계하실 수도 있습니다. 여기서 부터는 비용이 눈에띄게 발생하게 됩니다. 서비스의 특성에 따라 정형화된 데이터를 하나의 데이터소스에서 관리하고 싶다면 DW(Data warehouse)를, 비정형화 정형화 관계없이 여러 방식으로 데이터 플로우를 구축해야 한다면 하둡 레이어를, 비정형화 데이터를 관계처리 없이 사용하고자 한다면 MongoDB를, 수많은 데이터를 K-V(Key-Value) 형태로 확장성있게 분산기반 위에서 가져오고 싶다면 카산드라를 고려하실 수도 있습니다. 이러한 선택의 경우에는 각 요구사항에 여러 제품군이 있으며 각각의 대조군을 각 플랜에 맞게 테스트 하신 후 사용하시는 것을 권장합니다.

네번째는 서비스에 맞게끔 추가 서비스를 붙여 데이터 처리 플로우를 개선하는 방법이 있습니다. 여기서 부터는 하나의 데이터베이스 서비스가 아닌 다양한 서비스를 연구하고 조합해야 합니다. 예를들어 성능이 피크타임에 치솟고(보통 스파이크 친다고 합니다.) 데이터 삽입이 많이 발생하지만 관계형 쿼리를 많이 사용하지 않는 서비스에서는 (채팅 서비스: 챗봇, 메시지등의 대화형 서비스)에서는 nosql이나 앞단에 queue를 붙인 서비스를 고려하실 수 있습니다. 읽기 빈번하고 수정이 간간히 발생한다면 Redis나 Memcached 캐시 레이어를 앞단에 붙이는 구성을 고려 해 보실 수도 있습니다. 서비스 작업에 즉시성이 요구되지 않는다면 MapReduce를 통한 배치 방식을 고려하실 수도 있습니다.

NoSQL, DW, RealtimeDB, Serverless QueryEngine, Graph Database?!!!!?!

* 경고

모든 자료가 그렇듯이 모든 데이터베이스 엔진 혹은 쿼리 엔진의 장단점을 딥 다이브하여 검증하지 못하기 때문에 이 포스트를 통해 “우리 서비스는 ~~에 맞겠다" 라는 평가자료로 쓰일 수 없습니다. HDD를 주의 해주세요.

필자도 이런 부분에 전문가가 아니고 모든 레이어를 다 사용할 정도로 프로젝트의 규모가 거대하지도 않기 때문에 사실상 프로덕션에 적용해보지 않고 내리는 막연한 평가에 불가합니다.

1. NoSQL (Not only SQL)

전통적인 RDBMS 서비스를 이용하면서 생긴 불편사항들 (복잡한 관계 구조로 인해 생긴 제약들 - 분산, 열 용량 제약, 테이블 용량제약, 확장제약, 스키마로 인한 데이터 형식제약 등)을 벗어나고자 관계에 얼메여 있지 않은, 그리고 SQL외에 다른 표현식을 지원하는 새로운 데이터베이스가 나오게 되었는데 이를 NoSQL (Not only SQL)이라 부릅니다.

NoSQL 데이터베이스는 여러 종류가 있는데 일반적으로 RDBMS 처럼 기본 구조는 같은데 세부적으로 각각의 기능이 차이가 나는 것이 아니라 정말 핵심 기술부터 그 기능이 다른 종류들이 많습니다.

일반적으로 알려진 데이터베이스로는 MongoDB, Cassandra, HBase, Redis 등이 있으며 클라우드 환경에서는 AWS DynamoDB, Google Cloud BigTable 등이 있고 IBM도 DB2에서 NoSQL을 부분적으로 지원한다고 하는데 제가 사용안해봐서 잘 모르겠습니다.

NoSQL은 ACID를 지원하기 어렵습니다. 따라서 이를 완전히 지원해야하는 서비스에 적용하기 어렵습니다. CAP 이론으로 볼 때 보통 확정성(Scalability)을 위해 일관성(Consistency)을 보장하지 않습니다.

요새의 NoSQL에서는 GraphQL 지원을 하나 둘 하기 시작하여 이를 사용하기를 고려하는 업체에서는 테스트를 진행해보는 것이 좋을 것 같습니다.

각각의 NoSQL별 차이점이 존재하는데 간략히 작성하면 아래와 같습니다.

MongoDB

라이센스: GNU AGPL v3.0 (Free, and Commercial), Open source

업체: MongoDB Inc

리플리케이션: 지원 (M-S)

샤딩: 지원 (해시기반)

주관적 내용: 몽고 디비는 AGPL 라이센스를 가지고 있는데 (물론 커머셜 라이센스도 있습니다.) AGPL 라이센스는 상업적으로 사용이 가능하지만.. 모든 소스코드를 공개해야 하는 의무가 있습니다. (GPL의 경우 서버 통신을 하는 경우 회피 할 수 있는데, AGPL은 얄짤없이 공개해야 합니다.) 이는 사업에 있어 많이 고민해야 할 항목입니다. 그 밖에 기술적으로는 몽고 디비 파일이 깨지는 이슈라던가 복잡한 조인 구현 코드가 거의 살인급 코드라 그런 부분만 감당이 가능하면 사용하는 데 큰 지장은 없다고 봅니다. (겁나 겁주고 사용해도 좋다로 끝내는 훈훈함)

Cassandra

라이센스: Apache License 2.0 (Free), Open source

업체: Apache Software Foundation

리플리케이션: 지원 (replication_factor)

샤딩: 지원 (해시기반)

주관적 내용: 카산드라는 분산을 지정하는 옵션이 비교적 간단하고 이를 설정해 놓기만 해도 고가용성 분산 서비스로 동작되어 상당히 편리하긴 하지만 트랜잭션도 미지원, Secondary Index는 Range쿼리를 미지원 추가 Index 미지원 등등의 Trade Off 해야할 사항이 있으니 도입 시 충분히 검토해야 합니다.

HBase

라이센스: Apache License 2.0 (Free), Open source

업체: Apache Software Foundation

리플리케이션: 지원

샤딩: 지원

주관적 내용: 하둡 스택을 사용하는 업체라면 안쓸 이유가 더 없을 정도로 워낙 범용적으로 사용 되는 엔진입니다. HBase를 사용하는 이유야 뭐 하둡 분산파일시스템(HDFS) 위에 존재하는 거대한 데이터에서 빠르게 원하는 데이터를 뽑아낼 때 이기 때문에 특징이 뚜렷하다고 볼 수 있습니다. 당연하겠지만 HBase를 사용하기 위해서는 기본적인 하둡스택의 이해는 필요하기 때문에 진입장벽은 상대적으로 높습니다. 신기한 것은 HBase에서는 TTL을 지원하기 때문에 데이터의 만료시간을 관리할 수 있습니다. 마지막으로 HBase는 secondary index를 지원하지 않습니다. 따라서 일반적으로 RDBMS에서 사용하는 복잡한 관계 쿼리를 구현하실 수 없습니다.

Redis

라이센스: BSD 3-Clause (Free and Commercial), Open source

업체: Salvatore Sanfilippo

리플리케이션: 지원 (M-S)

샤딩: 미지원 (어플리케이션 레벨에서 Hash를 통해 지원해야 함)

주관적 내용: Redis는 인메모리 캐시 DB이기 때문에 역할군이 뚜렷합니다. 우선 안타까운 점은 Redis는 싱글 쓰레드 기반으로 설계되어 있습니다. 따라서 Redis 명령 중 일부는 블러킹을 걸도록 동작하기 때문에 프로덕션 레벨에서 운영할 때 치명적일 수 있습니다. Redis도 클러스터를 통한 분산과 센티넬을 통한 Fail-over를 제공하고 있으며 K-V, Hash, List, Set 등의 자료구조를 가지고 있습니다. RDB랑 AOF라는 연동 방식을 가지고 있는데 둘 모두 많은 수의 데이터를 관리하고 있다면 레디스 재시작에 많은 시간이 소요 될 수 있습니다. (저장의 경우 childProcess를 fork하여 진행합니다. // AOF는 rewrite의 경우에만 이렇게 동작합니다.) 같은 캐시 DB 레벨에 있는 Memcached랑 비교해보면 대부분의 응답속도와 성능의 경우 크게 차이는 없습니다. Redis는 replication에 에러에 대해서 처리 에러를 핸들링 할 수 있으며 동시에 여러 리플리케이션 구현이 가능합니다. 또한 아까 말씀드렸듯 Redis는 Memcached와 비교하였을 때 많은 데이터 타입을 제공하고 있는 장점을 가지고 있습니다. 다만 Flush 호출시 Memcached 동작방식과 전혀 다르기 때문에 블럭킹이 걸려 때문에 많은 양의 데이터를 Flush 할 경우 서비스 자체 동작에 문제가 발생할 수 있습니다. 그 밖에도 Redis는 Memcached에 비해 기존 저장된 데이터 유지를 위한 기능이 많습니다.

Memcached

라이센스: BSD 3-Clause (Free), Open source

업체: Danga_Interactive

리플리케이션: 지원 (repcached)

샤딩: 미지원 (어플리케이션 레벨에서 Hash를 통해 지원해야 함)

주관적 내용: Memcached는 Redis와 마찬가지로 인메모리 캐시 DB 영역에서 존재하고 있습니다. Redis와는 다르게 메모리 본연의 목적에 맞는 간단한 K-V 형태입니다. Redis와 비교 할 경우 크게 Flush all의 동작방식이 다르며 Memcached에서 훨씬 빠르게 동작합니다. (Memcached에서는 실제로 데이터 Flush를 일으키지 않고 timestamp를 기록하고 있다가 나중에 GET 되었을 때 이를 비교하여 삭제합니다.) 따라서 이러한 차이점이 오히려 동작처리에 있어 의도치 않을 실행을 하는 경우도 있습니다. Memcached에서는 flush all에 expired time을 옵션으로 줄 수 있는데 사전에 flush all로 삭제했다 하더라도 이후 flush all [exptime] 옵션을 통해 아직까지 삭제되지 않은 데이터를 재생 시킬 수 있습니다. (물론 exptime에 의해 언젠가는 삭제됩니다.)

DynamoDB

라이센스: 유료 라이센스 (요금보기)

업체: Amazon Web Service (AWS)

리플리케이션: 지원 (Server-less 구성, 자체 내결함성 지원)

샤딩: 지원 (Server-less 구성, 자체 분산)

주관적 내용: DynamoDB는 AWS에서 제공하는 클라우드 환경 베이스의 NoSQL DB 입니다. 여기서 큰 특징은 DynamoDB는 Server-less 환경이기 때문에 용량, 물리적 스팩 제한이 없으며 용량 크기, 사용자가 지정한 처리량(Through-put)에 맞게 알아서 확장되고 클러스터로 관리됩니다. 따라서 가용성, 확장성에 있어서 사용자로 하여금 귀찮은 작업이 많이 생략되며 Server-less이기 때문에 초기에 많은 비용이 나갈 우려가 사라집니다. 또한 Secondary index 지원을 Global, Local로 각각 지원하고 있습니다. 다만 관리형 서비스라 그런지 갑자기 많은 처리량이 발생할 때 DynamoDB에서 즉시 처리량을 늘릴 수 없는 문제, 그리고 이렇게 높아진 처리량을 다시 낮추는 경우에도 마찬가지로 제약이 있습니다. 따라서 이런 문제를 해결할려면 Warming up 작업을 해야하고 이로 인해 불필요한 비용이 발생할 수 있습니다. 마지막으로 놀라운 점이 하나 있는데 DynamoDB에서는 트랜잭션을 지원하기 위한 Java 코드가 올라와 있습니다.

Cloud Datastore

라이센스: 유료 라이센스 (요금보기)

업체: Google Cloud Platform (GCP)

리플리케이션: 지원 (Server-less 구성, 자체 내결함성 지원)

샤딩: 지원 (Server-less 구성, 자체 분산)

주관적 내용: Google Cloud Datastore는 AWS DynamoDB보다 약 4년정도 일찍 나온 서비스입니다. 가장 큰 차이로는 당연하게도 요금청구 방식이 다릅니다. (AWS DynamoDB는 Throughput 단위 청구, Google Cloud Datastore는 요청당 과금) 완전 정량적 과금이라 초기 비용이 적게 드는 합리적인 구성이지만 DynamoDB와 비교 할 때 요청이 많아질 수록 Google Cloud Datastore 요금이 더 비쌉니다. (읍�� 당신 누구야!?) 다만 secondary index라던지 Query 지원(GQL)이라던지 탈 NoSQL 요소들이 다분해서  이를 알고 사용하면 정말 유용하지만 신은 완벽을 내리지 않았다는 말이 증명되듯 이런 좋은 기능들에 대한 자료가 한없이 부족한 상태입니다.

Cloud Firestore

라이센스: 유료 라이센스 (요금보기)

업체: Google Cloud Platform (GCP) Firebase

리플리케이션: 지원 (Server-less 구성, 자체 내결함성 지원)

샤딩: 지원 (Server-less 구성, 자체 분산)

주관적 내용: 최근에 새롭게 출시된 (베타로) 데이터베이스로 필자는 Google Cloud Datastore와 대체 어떤 차이가 있는지 많이 혼동 되었습니다. 엄밀하게 Google Cloud Firestore의 경우에는 Firebase의 불편함 점 (Query의 불편함, 데이터 계층적 문제 등)을 보완하기 위한 부분이 있으며 Firebase의 목적 (Web, App의 지원)을 상속받기 때문에 Google Cloud Datastore 차이가 있습니다. (더군다나 Cloud Firestore는 Realtime을 지원합니다!) 따라서 Firebase Realtime Database와 비교하는 것이 더 바람직합니다. Cloud Firestore는 Firebase 및 Cloud Function 과 같은 GCP 제품을 호환할 수 있게 만들어 졌습니다.

2. DW (Data Warehouse)

예전에는 컴퓨터 하드웨어의 컴퓨팅 파워도 약했고 그렇기 때문에 수많은 데이터를 빠르게 분석 할 수 있는 환경도 여건도 없었습니다. 오늘 날에서는 컴퓨팅 파워도 높아졌고 또한 컴퓨팅 유닛도 굉장히 저렴해졌으며 가상화 기술과 분산 기술도 나날히 높아졌기 때문에 분산 환경에서 데이터를 실시간 분석하는 것이 가능해졌습니다. DW는 보통 OLAP을 위해 사용됩니다.

3. Realtime DB

Realtime DB는 실시간성 특징을 데이터베이스에 녹여 얻어낸 결과물이라 볼 수 있습니다. 일반적인 특징으로는 데이터베이스에서 수정이 발생하면 이를 클라이언트에 푸시하여 동기화 하는 기능이 들어가 있습니다. 대게의 Realtime DB는 NoSQL 기반이기 때문에 ACID를 요구하는 서비스에서 적용하기는 어렵습니다. 보통 실시간성이 요구되는 게임(진짜로 정말로 실시간 DB로 게임을 만드는 사례들이 있습니다.), 메시지 플랫폼(채팅, 챗봇, CS 등)에서 사용됩니다.

대표적인 Realtime DB 종류

Firebase Realtime DB

Cloud Firestore

RethinkDB

Druid (검토가 필요함)

4. Serverless query engine

Serverless라는 얘기는 서버가 진짜로 없는게 아니라 사용자 (엔지니어)에 있어서 서버가 가려져 있고 또 그것을 알 필요가 없도록 관리되고 있는 완전 관리형 서비스 입니다. 보통 이런 Serverless DB는 Cloud 환경에서 제공되고 있으며 해당 환경에 파일시스템(FS)에 쿼리를 요청하면 거기에 최적화된 코어 유닛의 서버를 런치하여 연산을 분산하기 때문에 상당히 빠른 쿼리 조회 시간을 제공합니다. 다만 코어 유닛의 조작이 불가능 하기 때문에 Scale 조정을 통해 성능을 개선 할 수 없습니다. 

대표적인 Serverless query engine의 종류

AWS Athena

AWS Spectrum (*반 Serverless라고 해야 할듯 합니다.)

AWS DynamoDB

Google BigQuery

Google Cloud Datastore

Firebase Realtime Database

5. Query engine

데이터베이스라고 불리우긴 어려우나 분명 쿼리를 통해 집계, 조건 등을 이용하여 결과 데이터를 산출하는 엔진을 칭합니다. 보통 따라붙는 수식어가 “Interactive Query”이며 공용 분산 파일시스템에서 데이터 레이크(Data lake) 역할을 하고 그를 조회하여 결과데이터를 뽑는 엔진을 Query engine이라 부릅니다.

대표적인 Query engine 종류

앞서 거론한 모든 Serverless query engine

Apache Impala

Apache Hive

Apache Pig

Apache Drill

IBM BigSQL

Apache Tajo

Facebook Presto

6.Graph Database

최근에 자주보이는 데이터베이스입니다. 필자는 새롭게 나오는 논문을 살펴보는 스타일은 아닌지라 이것이 어디에서 따와서 점차 출시되고 있는지 잘 모르겠습니다. DAG(Directed Acyclic Graph) 기반의 그래프 데이터베이스 형태로 출시되고 있습니다.

대표적인 Graph Database의 종류

SQL Server 2017

Teradata Aster

SAP HANA

Neo4j

DynamoDB Titan (검증 후 재 업데이트 예정)

Apache S2Graph

참고하거나 연관 된 포스팅 목록

Amazon Redshift: Performance Tuning and Optimization (Slideshare)

오픈소스 데이터베이스, 은행 서비스에 첫발을 내밀다. (Slideshare)

[야생의 땅: 듀랑고] 서버 아키텍처 - SPOF 없는 분산 MMORPG 서버 (Slideshare)

Apache Cassandra 톺아보기 - 1편 (NHN-Enter Toast)

Apache Cassandra 톺아보기 - 2편 (NHN-Enter Toast)

Apache Cassandra 톺아보기 - 3편 (NHN-Enter Toast)

Dremel: Interactive Analysis of Web-Scale Datasets (Research at Google)

Kafka New Producer API를 활용한 유실 없는 비동기 데이터 전송 (SK플래닛 기술 블로그)

구글 클라우드 데이터스토어에서 스트롱 컨시스턴시와 이벤츄얼 컨시스턴시의 균형잡기 (nurinamu‘s the BLACK BOOK)

[분산캐시] Redis 와 memcache의 flush는 왜 다를까? (Charsyam's Blog)

ZooKeeper를 활용한 Redis Cluster 관리 (Naver D2)

Memcached의 확장성 개선 (Naver D2)

글로벌 분산 데이터베이스 Spanner (Naver D2)

왜 레진코믹스는 구글앱엔진을 선택했나 (Slideshare)

카카오 “레디스, 잘못쓰면 망한다" (ZDNet Korea)

Apache spark 소개 및 실습

[siva3155]

300+ TOP NAGIOS Interview Questions and Answers

NAGIOS Interview Questions for freshers experienced :-

1. What is Nagios? Nagios commonly known as the Nagios core is the open-source software that is designed to monitor networks, systems, applications, and infrastructures. The software directly sends the track down all the changes in the subject and send alerts if necessary. 2. How Nagios help DevOps professionals? Nagios was designed in the first place to monitor applications, networks, and infrastructures. The software automatically keeps an eagle eye and immediately report in case of failure. The quick response helps the DevOps professional to track down and resolve the problem in the early stages before it can cause any serious damage to the organization. 3. What makes Nagios an ideal tool for continuous monitoring? The below features of the Nagios is what makes it an ideal tool for continuous monitoring: Automatic problem fixing Infrastructure upgrades Business process and infrastructure monitoring Quick respond to the system issues 4. Write down some of the names of the Nagios monitoring tool for Linux mentoring? When you are using the Nagios to monitor the Linux environment then you need to understand that you are using one of the best tools on the planet. The complete package of Nagios includes service state, file system usage, system metrics, process state, and more. 5. How Icinga is related to the Nagios? Icinga is also open-source software that is used to monitor the networks and application. The core objective of designing Icinga in the first place to lift up the Nagios back in 2009. But it works as a separate monitor software. 6. Describe the active and passive check in Nagios In the Nagios, an active check is leveraged to “poll” a service or device for the status information every once in a while. Nagios basically supports the way to host down the devices and services passively. The key feature of the passive check is it can only be performed by the external applications. 7. Explain OID Nagios? Simple Network Management Protocol (SNMP)- a network protocol which is also designed for the monitoring purpose uses the Object Identifiers to define the Management Information Base. 8. Can you use Nagios to monitor the window machine? Yes, you can use Nagios to monitor the window machine. However, if you are doing it for the first time then you have to follow the given steps: Set the Nagios to monitor the window system Add a separate host and server for the window monitoring 9. Describe the Nagios XI? On the current basis, Nagios XI is one of the most powerful monitoring software in the market. when it comes to monitoring critical infrastructures such as network protocols, applications, services, systems metrics, and network protocols experts only relies upon the Nagios XI. 10. Highlights the benefits of using Nagios for monitoring? There are various benefits of using Nagios software for critical monitoring. The list of benefits includes: Infrastructure updates before the outdated system cause any sort of failure Automatic tracking and troubleshooting of problem Coordinate responses Continuously Monitor infrastructure without any break Response to issues on an immediate basis

NAGIOS Interview Questions 11. what active check means? Active check is the globally recognized way to monitor the hosts and services. Both Nagios XI and Nagios core use it on the pre-determined schedule. 12. Describe the Nagios Network Analyzer? A network analyzer is a crucial aspect of the Nagios software that allows it to deeply scan the entire system in a search of any potential threat. The quick and reliable scan allow system admin to gather necessary data regarding the health of the system and granular data through network analysis. 13. Highlight the primary benefits of monitoring the websites with Nagios? The key benefits of monitoring websites with Nagios are given below: It enhances the website availability Increase website performance Quick detection of online threats such as bugs and hijacking 14. Name down some databases that support Nagios monitoring? There are a number of databases that support Nagios and some of them are mentioned below: Oracle MySQL Microsoft SQL software Postgres 15. Write down the protocols that support Nagios Nagios supports the number of protocols monitoring including; SMTP Monitoring, IPMI Monitoring, FTP Monitoring, LDAP Monitoring, POP Monitoring, and DNS monitoring. 16. what do you understand by the fact that Nagios is object-oriented? As already mentioned above, Nagios is open-source object-oriented monitoring software. Here the term “object-oriented” means that users can create the object definitions in the Nagios that inheritance from other objects. This essential feature of the Nagios further simplifies the complex relationship between components. 17. Can I use Nagios for both cloud computing and cloud monitoring? Yes, the Nagios has a reputation as one of the best monitoring software in the market and you can use it for various monitoring purposes including both virtual and physical. 18. state the name of any four virtualization platforms that supports Nagios? VMware, Amazon EC2, Xen and Microsoft Virtual PC are some of the most common examples of the virtualization platforms that support the Nagios monitoring. 19. Do you know the port numbers Nagios use to monitor its clients? Yes, the Nagios uses port number; 5666, 5667 and 5668 to monitor its clients. 20. Describe the process to verify the Nagios configuration? If you want to configure the Nagios, then you have to run it with the -v command line with option like: nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg. 21. Define the objects in Nagios? In the Nagios, objects refer to all the elements that are involved in the entire monitoring and alerting logic. 22. What are the types of objects you can witness in Nagios? The types of objects you can witness in the Nagios includes; Services, Hosts, commands, host groups, contact, time periods, and notification escalations. 23. How can you use plugin X in Nagios? Just like any other plugin, you have to download plugin X from the official website of Nagios which is https://exchange.nagios.org/. Once downloaded, you can run it manually to see if it is working correctly. 24. When it comes to monetary terms what is the main difference between Nagios Core and Nagios XI? Well, when it comes to monetary terms, Nagios Core is the free open source version while Nagios XI is the paid version limited to the individual who held the license. 25. What is the current Nagios state type? On the current basis, the monitoring host and services are determined by the two major components First: Status of the host and service Second: Types of the state the host or service is in 26. What are the two main state types in Nagios? The Nagios have two key state types; soft states and hard states. 27. Define NRPRE in Nagios? The term NRPE stands for the Nagios Remote Plugin Executor addon which is specifically designed by the experts to execute Nagios plugins on the Linux machines. 28. What database format Nagios support to store status data? RRD is the database format Nagios support and uses to store the status data. 29. Write down the components of NDO Utilities? The NDO utilities are the right mixture of the: NDOMOD Event Broker Module FILE2SOCK Utility LOG2NDO Utility NDO2DB Daemon 30. Can we monitor the operating system through Nagios? Yes, you can monitor any operation system through Nagios as long as it supports the software. NAGIOS Questions and Answers Pdf Download Read the full article

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How do you know which is the better website company?

The best website development company in Gurgaon: Being the top web development companies in India, they have to follow the latest trends in the development industry, and try their best to be on the top position. The web revolved around the internet and WWW, whatever is happening around the internet and browsers. Nowadays, the browser doesn’t support the old language. So, you have to update your website according to it.

A full-stack developer knows the language which we used at the client-side, and also they know about the backend language. The client-side means where the user interacts with the browser and the backend means where the user has no involvement. The backend mean server area where the only developer knows what is going on? The client-side languages are HTML, CSS, Javascript. The backend means server and database. The server languages are PHP, Dot net, Java, Python, NodeJS, etc. The SQL languages are Oracle, My SQL, Mongo DB, etc. The best website development company in Gurgaon has the full-stack developers and knows about both the client-side and server-side.

The best website development company in Gurgaon follows a systematic pattern so that they won’t be late in the delivery of their projects. This is another reason to know which is the better company? The systematic pattern is known by the web development life cycle. The life cycle has the following steps, namely:

Project planning: Before beginning your project, you should plan the overall strategy to follow and make a road map.

Requirement definitions: After making a whole plan, now it’s time for making a list of requirements.

Design: After knowing the requirements, this is the time for the designer team to design a layout and make attractive banners and web pages.

Development: Now, developers code the website and fetch their data in the database. The developer makes sure the website works perfect on the internet.

Integration and test: After the developer completes the coding, the tester checks the work and finds out an error if any, before sending it to the client.

Installation and acceptance: After the tester gives the green signal, they show it to the client. After acceptance by the client, maintenance teamwork start of installation.

After the introduction of IoT, The web industry grows more than ever. What is IoT? IoT means connecting computers, digital machines, objects, animals or people who have unique identifiers, and the ability to transfer data from human to human or human to computer. The IoT is successful because of the sensors  and the real-time analogies they have used. Applications of IoT which are successfully running are:

1) Smart home and elder care: Smart home means you can control your home appliances with your phone or by your little interaction like a clap. For example, if you clap one time light is switched on and if you clap two then the light is switched off. The elder care is the most important and useful because the elderly could not do the work properly but with the help of IoT they can do and IoT can help them.

2) Medical and health care: IoT for medical care related purposes like data collection, analysis for research and monitoring. Smart health care means digitize everything. IoT helps doctors to monitor remotely. The web development company in Gurgaon uses the latest trends to make websites.

3) Transportation: IoT helps in transportation and smart traffic control. IoT tells you about delays, damages of the road before you leave the house.

IoT is a great innovation in the web industry. The website development company in Gurgaon provides you the best services and deliver you on time, that is why It is the best web development company in Gurgaon.