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𝗧𝗼𝗽 𝟮𝟬 𝗦𝗤𝗟 𝗾𝘂𝗲𝗿𝘆 𝗼𝗽𝘁𝗶𝗺𝗶𝘇𝗮𝘁𝗶𝗼𝗻 𝘁𝗲𝗰𝗵𝗻𝗶𝗾𝘂𝗲𝘀

Here is the list of the top 20 SQL query optimization techniques I found noteworthy:

1. Create an index on huge tables (>1.000.000) rows
2. Use EXIST() instead of COUNT() to find an element in the table
3. SELECT fields instead of using SELECT *
4. Avoid Subqueries in WHERE Clause
5. Avoid SELECT DISTINCT where possible
6. Use WHERE Clause instead of HAVING
7. Create joins with INNER JOIN (not WHERE)
8. Use LIMIT to sample query results
9. Use UNION ALL instead of UNION wherever possible
10. Use UNION where instead of WHERE ... or ... query.
11. Run your query during off-peak hours
12. Avoid using OR in join queries
14. Choose GROUP BY over window functions
15. Use derived and temporary tables
16. Drop the index before loading bulk data
16. Use materialized views instead of views
17. Avoid != or <> (not equal) operator
18. Minimize the number of subqueries
19. Use INNER join as little as possible when you can get the same output using LEFT/RIGHT join.
20. Frequently try to use temporary sources to retrieve the same dataset.

Do you know what is 𝗤𝘂𝗲𝗿𝘆 𝗢𝗽𝘁𝗶𝗺𝗶𝘇𝗲𝗿? Its primary function is to determine 𝘁𝗵𝗲 𝗺𝗼𝘀𝘁 𝗲𝗳𝗳𝗶𝗰𝗶𝗲𝗻𝘁 𝘄𝗮𝘆 to execute a given SQL query by finding the best execution plan. The query optimizer takes the SQL query as input and analyzes it to determine how best to execute it. The first step is to parse the SQL query and create a syntax tree. The optimizer then analyzes the syntax tree to determine how to run the query.

Next, the optimizer generates 𝗮𝗹𝘁𝗲𝗿𝗻𝗮𝘁𝗶𝘃𝗲 𝗲𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻 𝗽𝗹𝗮𝗻𝘀, which are different ways of executing the same query. Each execution plan specifies the order in which the tables should be accessed, the join methods, and any filtering or sorting operations. The optimizer then assigns a 𝗰𝗼𝘀𝘁 to each execution plan based on the number of disk reads and the CPU time required to execute the query.

Finally, the optimizer 𝗰𝗵𝗼𝗼𝘀𝗲𝘀 𝘁𝗵𝗲 𝗲𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻 𝗽𝗹𝗮𝗻 with the lowest cost as the optimal execution plan for the query. This plan is then used to execute the query.
1
Complete HTML in 2 Minutes🔥

Here we go👇

1.Document Structure
• <!DOCTYPE>
• <html>
• <head>
• <title>
• <meta>
• <link>
• <script>
• <noscript>

2.Text Content
• <h1>, <h2>, <h3>, <h4>, <h5>, <h6>
• <p>
• <span>
• <strong>
• <em>
• <br>
• <hr>

3.Lists
• <ul>
• <ol>
• <li>
• <dl>
• <dt>
• <dd>

4.Links and Navigation
• <a>
• <nav>
• <link>

5.Embedded Content
• <img>
• <audio>
• <video>
• <iframe>
• <canvas>
• <svg>

6.Forms
• <form>
• <input>
• <textarea>
• <button>
• <select>
• <option>
• <label>
• <fieldset>
• <legend>
• <datalist>
• <output>

7.Tables
• <table>
• <tr>
• <th>
• <td>
• <caption>

8.Semantic Elements
• <article>
• <section>
• <header>
• <footer>
• <aside>
• <main>
• <figure>
• <figcaption>
• <mark>
• <progress>
• <time>
• <details>
• <summary>

9.Deprecated Elements (Avoid Using)
• <center>
• <font>
• <strike>


@javascript_resources
@python_assets
3
As web developer, you need to master writing API.

And a common question I got asked is: what is 'RESTful' API? 🤔

Here's a mega thread about RESTful API and how to write it:

First of all, REST stands for 'REpresentational State Transfer', it is an architectural style of writing API.

It includes the following 6 features:
1. Uniform interface

The API should be written with unique and consistent methods of resource identification and manipulation, with clear messages to define actions and information.

(continue 👇)

2. Client-server architecture 🛎️

The principle of 'Separation of concerns' is applied here - we want to separate the user interface vs. data storage.

(continue 👇)


3. Statelessness 📍

Each request must already contain all knowledge needed to complete the request.

(continue 👇)


4. Cacheability 📥

Allowing identification of cacheable contents, and to avoid stale or inappropriate data.

(continue 👇)

5. Layered system 🍰

There should be hierarchical layers of components, without affecting communication between client and server (e.g., proxy and load balancers).

(continue 👇)


6. Code-on-demand (optional) 👩‍💻

Executable code can be sent from server to provide extra temporary functionalities,

(continue 👇)


Here's some common pattern of RESTful API:

📌 List container contents: GET /items
📌 Add an item to container: POST /items
- with item in request
- URI of item returned in HTTP response header, e.g. Location: http://host/items/itemid

(cont'd) 👇


📌 Retrieve an item: GET /items/itemid
📌 Update an item: PUT /items/itemid
- with updated item in request
📌 Delete an item: DELETE /items/itemid

(cont'd)


In a nutshell, a well written RESTful API is:

Easy to work with
Uniformed
Scripting language friendly


@javascript_resources
@python_assets
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HTML tip:

You can use the download attribute in your links to download the file instead of navigating to it:
Check out these 15 fascinating Free (public) APIs:

👩 Genderize .io
🔍 IMDb API
📦 Dropbox API
🚀 NASA API
📱 Twilio API
🌤️ OpenWeatherMap API
🍔 Open food facts
💬 Slack API
🐙 GitHub API
👕 Shopify API
💰 PayPal API
💳 Stripe API
🤖 Reddit API
📂 OneDrive API
🦠 VirusTotal API

@javascript_resources
@python_assets
A-Z Git in 2 minutes 🔥

here we go👇

1. Core:
• git init
• git clone
• git add
• git commit
• git status
• git diff
• git checkout
• git reset
• git log
• git show
• git tag
• git push
• git pull

2.Branching:
• git branch
• git checkout -b
• git merge
• git rebase
• git branch --set-upstream-to
• git branch --unset-upstream
• git cherry-pick

3.Merging:
• git merge
• git rebase

4.Stashing:
• git stash
• git stash pop
• git stash list
• git stash apply
• git stash drop

5.Remotes:
• git remote
• git remote add
• git remote remove
• git fetch
• git pull
• git push
• git clone --mirror

6.Configuration:
• git config
• git global config
• git reset config

7. Plumbing:
• git cat-file
• git checkout-index
• git commit-tree
• git diff-tree
• git for-each-ref
• git hash-object
• git ls-files
• git ls-remote
• git merge-tree
• git read-tree
• git rev-parse
• git show-branch
• git show-ref
• git symbolic-ref
• git tag --list
• git update-ref

8.Porcelain:
• git blame
• git bisect
• git checkout
• git commit
• git diff
• git fetch
• git grep
• git log
• git merge
• git push
• git rebase
• git reset
• git show
• git tag

9.Alias:
• git config --global alias.<alias> <command>

10.Hook:
• git config --local core.hooksPath <path>

11.Experimental: (May not be fully Supported)
• git annex
• git am
• git cherry-pick --upstream
• git describe
• git format-patch
• git fsck
• git gc
• git help
• git log --merges
• git log --oneline
• git log --pretty=
• git log --short-commit
• git log --stat
• git log --topo-order
• git merge-ours
• git merge-recursive
• git merge-subtree
• git mergetool
• git mktag
• git mv
• git patch-id
• git p4
• git prune
• git pull --rebase
• git push --mirror
• git push --tags
• git reflog
• git replace
• git reset --hard
• git reset --mixed
• git revert
• git rm
• git show-branch
• git show-ref
• git show-ref --heads
• git show-ref --tags
• git stash save
• git subtree
• git tag --delete
• git tag --force
• git tag --sign
• git tag -f
• git tag -l
• git tag --verify
• git unpack-file
• git update-index
• git verify-pack
• git worktree

------------------- END ------------------
👍2
HTML Tip💡
@javascript_resources
@python_assets

You can use the "loading" attribute with the <img> element to control how the browser loads the image.

It has three values: "eager", "lazy", and "auto".
👍1
Reactjs & Nodejs in 2 minutes🔥

Here we go👇

-: React.Js :-
1.Components
• Functional Components
• Class Components
• JSX (JavaScript XML) Syntax

2.Props (Properties)
• Passing Props
• Default Props
• Prop Types

3.State
• useState Hook
• Class Component State
• Immutable State

4.Lifecycle Methods (Class Components)
• componentDidMount
• componentDidUpdate
• componentWillUnmount

5.Hooks (Functional Components)
• useState
• useEffect
• useContext
• useReducer
• useCallback
• useMemo
• useRef
• useImperativeHandle
• useLayoutEffect

6.Event Handling
• Handling Events in Functional Components
• Handling Events in Class Components

7.Conditional Rendering
• if Statements
• Ternary Operators
• Logical && Operator

8.Lists and Keys
• Rendering Lists
• Keys in React Lists

9.Component Composition
• Reusing Components
• Children Props
• Composition vs Inheritance

10.Higher-Order Components (HOC)
• Creating HOCs
• Using HOCs for Reusability

11.Render Props
• Using Render Props Pattern

12.React Router
• <BrowserRouter>
• <Route>
• <Link>
• <Switch>
• Route Parameters

13.Navigation
• useHistory Hook
• useLocation Hook

State Management
14.Context API
• Creating Context
• useContext Hook

15.Redux
• Actions
• Reducers
• Store
• connect Function (React-Redux)

16.Forms
• Handling Form Data
• Controlled Components
• Uncontrolled Components

17.Side Effects
• useEffect for Data Fetching
• useEffect Cleanup

18.AJAX Requests
• Fetch API
• Axios Library

Error Handling
19.Error Boundaries
• componentDidCatch (Class Components)
• ErrorBoundary Component (Functional
Components)

20.Testing
• Jest Testing Framework
• React Testing Library

21. Best Practices
• Code Splitting
• PureComponent and React.memo
• Avoiding Reconciliation
• Keys for Dynamic Lists

22.Optimization
• Memoization
• Profiling and Performance Monitoring

23. Build and Deployment
• Create React App (CRA)
• Production Builds
• Deployment Strategies

Frameworks and Libraries
24.Styling Libraries
• Styled-components
• CSS Modules

25.State Management Libraries
• Redux
• MobX

26.Routing Libraries
• React Router
• Reach Router

-: Node.js :-

1.Introduction to Node.js
• JavaScript Runtime for
Server-Side Development
• Non-Blocking I/O

@javascript_resources

2.Setting Up Node.js
• Installing Node.js and NPM
• Package.json Configuration
• Node Version Manager (NVM)

3.Node.js Modules
• CommonJS Modules (require, module.exports)
• ES6 Modules (import, export)
• Built-in Modules (e.g., fs, http, events)

4.Core Concepts
• Event Loop
• Callbacks and Asynchronous Programming
• Streams and Buffers

5.Core Modules
• fs (File System)
• http and https (HTTP Modules)
• events (Event Emitter)
• util (Utilities)
• os (Operating System)
• path (Path Module)

6.NPM (Node Package Manager)
• Installing Packages
• Creating and Managing package.json
• Semantic Versioning
• NPM Scripts

7.Asynchronous Programming in Node.js
• Callbacks
• Promises
• Async/Await
• Error-First Callbacks

8. Express.js Framework
• Routing
• Middleware
• Templating Engines (Pug, EJS)
• RESTful APIs
• Error Handling Middleware

9.Working with Databases
• Connecting to Databases (MongoDB, MySQL)
• Mongoose (for MongoDB)
• Sequelize (for MySQL)
• Database Migrations and Seeders

10.Authentication and Authorization
• JSON Web Tokens (JWT)
• Passport.js Middleware
• OAuth and OAuth2

11. Security
• Helmet.js (Security Middleware)
• Input Validation and Sanitization
• Secure Headers
• Cross-Origin Resource Sharing (CORS)

12.Testing and Debugging
• Unit Testing (Mocha, Chai)
• Debugging Tools (Node Inspector)
• Load Testing (Artillery, Apache Bench)

13.API Documentation
• Swagger
• API Blueprint
• Postman Documentation

14.Real-Time Applications
• WebSockets (Socket.io)
• Server-Sent Events (SSE)
• WebRTC for Video Calls
👍6
15.Performance Optimization
• Caching Strategies (in-memory, Redis)
• Load Balancing (Nginx, HAProxy)
• Profiling and Optimization Tools (Node Clinic,
New Relic)

16.Deployment and Hosting
• Deploying Node.js Apps (PM2, Forever)
• Hosting Platforms (AWS, Heroku, DigitalOcean)
• Continuous Integration and Deployment-
(Jenkins, Travis CI)

17.RESTful API Design
• Best Practices
• API Versioning
• HATEOAS (Hypermedia as the Engine-
of Application State)

18.Middleware and Custom Modules
• Creating Custom Middleware
• Organizing Code into Modules
• Publish and Use Private NPM Packages

19.Logging
• Winston Logger
• Morgan Middleware
• Log Rotation Strategies

20.Streaming and Buffers
• Readable and Writable Streams
• Buffers
• Transform Streams

21.Error Handling and Monitoring
• Sentry and Error Tracking
• Health Checks and Monitoring Endpoints

22.Microservices Architecture
• Principles of Microservices
• Communication Patterns (REST, gRPC)
• Service Discovery and Load Balancing
in Microservices
1👍1