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The State of Email in 2026: what 50,000 domains reveal about MX, SPF & DMARC
By the team at MailTester Ninja — a real-time email verification API that stores nothing. We verify a lot of email for a living. So we pointed our infrastructure at a representative panel of 50,000 of the world's most-linked domains and measured how email is actually configured in 2026 — MX providers, SPF and DMARC. Pure DNS, aggregate only, no personal data . Here's what the internet's mail setup looks like right now. Email is still (almost) everywhere 79.9% of these domains are mail-enabled (they publish MX records). Email isn't going anywhere. Authentication: adopted, but not enforced 75.8% publish an SPF record 64% publish a DMARC record …but only 22.6% actually enforce it with p=reject That last number is the real story. Of the domains that bother to publish DMARC, only 35.2% are on p=reject — the rest sit on p=none (37.2%, monitoring only) or quarantine (27.6%). Most of the web announces a policy it doesn't enforce. That's a deliverability and spoofing gap hiding in plain sight. Who runs the world's inboxes? Other / self-hosted — 32.6% Google Workspace / Gmail — 28.2% Microsoft 365 / Outlook — 22.5% Proofpoint — 5.5% Mimecast — 3.1% Tencent QQ — 2% Namecheap — 1.3% Cisco IronPort — 0.9% Self-hosted and the two hyperscalers (Google Workspace and Microsoft 365) dominate, but the long tail of providers is very real — which is exactly why deliverability is hard: every provider blocks, greylists and reputation-scores differently. Why we publish this We built an open, daily-updated dataset and a live dashboard because deliverability decisions should be based on data, not folklore. It's CC BY 4.0 — use it, cite it, build on it. Want to check a specific domain? Our free analyzer shows any domain's MX / SPF / DMARC in one click — no signup, nothing stored. Methodology: Live DNS scan (MX/SPF/DMARC). Aggregate only — no email sent, no personal data. Sample updated Wed, 01 Jul 2026 12:31:00 GMT.
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How to right-size RDS instances without downtime
Quick Answer (TL;DR) Modifying an RDS instance class in place causes 5 to 15 minutes of downtime while AWS reboots the database. To right-size without downtime, use RDS Blue/Green Deployments (fastest, cleanest), a read-replica promotion (works on older engines), or a Multi-AZ failover to a resized standby. Blue/Green is the 2026 default for most workloads on MySQL, MariaDB, Postgres, and now SQL Server. Why this happens RDS instances are Managed EC2 hosts running the DB engine, and a class change (say db.m6i.large to db.m6i.xlarge ) requires stopping the process, migrating the EBS volumes to a new host, and restarting. AWS's default "modify" workflow does this in place and warns you about downtime. The workarounds exist because that reboot is unacceptable for user-facing services, so you build the new instance alongside the old one and cut over. Fix #1: Use RDS Blue/Green Deployments The 2026 default. Available for RDS MySQL, MariaDB, PostgreSQL, and SQL Server (added mid-2025). Steps: In the RDS console, select the instance and choose Actions → Create Blue/Green Deployment . Set the Green instance to your target instance class. AWS creates a full standby using logical replication, keeps it in sync, and validates health. When ready, click Switch over . Cutover typically takes under 60 seconds. Applications reconnect using the same endpoint. Command-line equivalent: aws rds create-blue-green-deployment --blue-green-deployment-name resize-prod --source arn:aws:rds:... --target-db-instance-class db.m6i.xlarge Best when: your engine supports it and you can tolerate the extra cost of running two instances for the sync window. Fix #2: Read-replica promotion For engines or versions that do not yet support Blue/Green, or for cross-region resizing. Steps: Create a read replica with the desired new instance class. Wait for the replica to catch up (near-zero lag). Point application writes to the read replica endpoint (requires connection-string change or DNS switch). Promote
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Article on Modelling, Joins, Relationships and Different Schemas In Power BI
Data Modeling, Relationships, and Schemas in Data Analytics In the fields of data analytics, data warehousing, and database management, modeling and schema design are the fundamental pillars used to organize and query information efficiently. This article provides a comprehensive guide to these core concepts. 1. Data Modeling Data modeling is the architectural process of designing how data is stored, interconnected, and accessed within a system. Core Questions Addressed: Storage: What specific data points need to be captured? Structure: How should individual tables be organized? Connectivity: How do these tables interact with one another? Levels of Data Models: Conceptual Model: A high-level business perspective focusing on entities and their relationships, devoid of technical specifications. Logical Model: Defines specific attributes, keys, and relationships. It is independent of the Database Management System (DBMS). Physical Model: The actual implementation within a database, including technical details like indexes, partitions, and storage requirements. 2. Relationships Relationships define the logic of how data in one table corresponds to data in another. One-to-One (1:1): A single record in Table A relates to exactly one record in Table B. One-to-Many (1:M): The most common relationship; for example, one Customer can place many Orders . Many-to-Many (M:M): Multiple records in one table relate to multiple records in another. This requires a Junction Table (Bridge Table) to function. Example: One Student can enroll in many Courses, and one Course contains many Students. 3. SQL Joins Joins are used to combine rows from two or more tables based on a related column. Join Type Description Inner Join Returns only the records that have matching values in both tables. Left Join Returns all records from the left table and the matched records from the right. Right Join Returns all records from the right table and the matched records from the left. Full Outer Join Returns
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Learn DynamoDB by running it - accesspatterns.dev
I've been building on DynamoDB since around 2015, and these days I build tools for it: dynoxide , a DynamoDB engine, and Nubo , a native client. So I'm not neutral about it. It's the first database I reach for, and with reason - the operational overhead is close to nil, no connections to pool or instances to size, and it holds the same single-digit-millisecond reads whether the table has a thousand items or a billion. The data modelling is a craft, and a satisfying one. It's also one of the harder databases to learn, and that's the part I keep coming back to. DynamoDB punishes the instincts you bring from SQL. You don't normalise and join at read time; you work out the questions your app will ask first, and shape the data around those access patterns, until one table answers all of them. It's a real shift in how you think, and it's where a lot of people bounce off - it feels backwards right up until it clicks. The people who teach it best all teach it the same way. Alex DeBrie's The DynamoDB Book , the arc.codes team's examples, Rick Houlihan's re:Invent talks - the legendary ones, where he models half a dozen access patterns onto a single table at a hundred miles an hour - none of them hand you rules to memorise. They show you patterns and make you run them. I learned a lot of my DynamoDB from all three, and it stuck because I was building as I went. That last part is the bit that's hard to come by on your own. Reading about an access pattern and having it in your fingers are different things, and to run one - build the table, write the items, fire the query and see what comes back - you need an AWS account, or a local emulator installed and seeded. Enough friction that plenty of people read about single-table design without ever building one. There was a second thing pulling the same way. dynoxide had learned to run in the browser only last month, compiled to WebAssembly with no server behind it, and it was a preview I didn't fully trust. What it needed was a real
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DATA MODELLING RELATIONSHIPS AND SCHEMAS IN POWER BI
INTRODUCTION When I started using Power BI, I only thought of visuals like charts and graphs. However, as I progressed, I discovered a great data dashboard is built on great data models. Data Modelling is the process of organizing your data tables and defining how they relate to each other so Power BI can combine them into meaningful reports and dashboards. Good, designed data makes it easier and faster to maintain. Why is data Modelling Important Well-organized data makes it easier to manage data. Reduction of the duplicates. Ensures data consistency. Understanding Relationships Relationships allow the data table to give communication using fields. For example, Customer Table stores all information about a customer. Product Table store product details Sales Table stores all information about the transactions. Power BI connects the information between the customer’s name and Customer Id rather than repeating them it connects the information using joins. Going through relationships I discovered schemes. Scheme is the way tables are organized in databases. There are different types of schemes e.g. Star Schema, snowflake schema and Flat table. Star Schema A star schema is a data model with one central fact table and dimension table surrounding it. Fact table A table that stores events, transactions of what happened. • Total sales • average sales • quantity sold Dimension table A dimension table describes the items in the fact table. The table contains descriptive information. • The customer table describes the customer • How much sales were made The fact table sits in the center, while the dimension tables surround it—forming a star. Dashboard designs A good dashboard has to fit one page. A dashboard should show critical information. Update automatically when data changes. Focus on data understanding and decision making. Conclusion Power BI taught me that a great report are built from a a great dashboard which is achieved by having great models. Structuring a data into
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I Moved My Next.js Dashboard Logic Into Postgres. My Frontend Got Boring (And That's the Point).
My dashboard had a useMemo doing arithmetic it had no business doing. It was a Pokémon TCG Pocket collection tracker, but that part doesn't matter. What matters is that the home page needed to show three things: overall completion, completion per set, and which set you were closest to finishing. The way I'd built it, the browser was fetching every card and every owned record, then grinding through the math on each render to figure all of that out. It worked. It also got slower and harder to read every time the data grew or I added a metric. So I moved the aggregation out of React and into Postgres, and the surprising result was that my frontend got boring . Fewer hooks, less state, almost nothing left to break. That's the whole argument of this post: aggregation belongs in the database, and when you put it there, the React code that's left over is the kind of boring you actually want in the layer your users touch. What "fetching everything into React" actually looks like Here's the shape of the original dashboard. Load all the cards, load the user's owned rows, then derive everything on the client. const [ cards , setCards ] = useState < Card [] > ([]); const [ owned , setOwned ] = useState < OwnedCard [] > ([]); useEffect (() => { ( async () => { const { data : allCards } = await supabase . from ( " cards " ). select ( " * " ); const { data : ownedRows } = await supabase . from ( " user_cards " ) . select ( " card_id " ); setCards ( allCards ?? []); setOwned ( ownedRows ?? []); })(); }, []); const ownedIds = useMemo (() => new Set ( owned . map (( o ) => o . card_id )), [ owned ]); const perSet = useMemo (() => { const groups : Record < string , { total : number ; have : number } > = {}; for ( const card of cards ) { const g = ( groups [ card . set_id ] ??= { total : 0 , have : 0 }); g . total += 1 ; if ( ownedIds . has ( card . id )) g . have += 1 ; } return groups ; }, [ cards , ownedIds ]); const overall = useMemo (() => { const total = cards . length ; const ha
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Elastic Open-Sources Atlas Agent Memory Based on Cognitive Science
Elastic open-sourced Atlas, a system built on Elasticsearch that maintains three categories of memory for agents. Atlas integrates with agents via MCP and maintains per-user isolation of memories. When evaluated on question-answering capability, it scored 0.89 Recall@10. By Anthony Alford
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Building a Denim Collection API: A Practical Guide to Handling Product Variants
If you've ever worked with e-commerce data, you know that "a pair of jeans" is never just one product. A single style might come in 5 washes, 8 sizes, and 3 inseam lengths. That's 120 potential SKUs. Handling this correctly in an API can be tricky, so let me share a pattern I've used for structuring product variants. The core problem is balancing flexibility with performance. You want customers to filter by size, color, and fit without making dozens of API calls. Here's a simple but effective approach using a normalized database schema with a flat query layer: -- Products table (the "parent") CREATE TABLE products ( id UUID PRIMARY KEY , name TEXT NOT NULL , description TEXT , base_price DECIMAL ( 10 , 2 ), category TEXT ); -- Variants table (the actual sellable items) CREATE TABLE variants ( id UUID PRIMARY KEY , product_id UUID REFERENCES products ( id ), sku TEXT UNIQUE NOT NULL , size TEXT , color TEXT , wash TEXT , inseam TEXT , price DECIMAL ( 10 , 2 ), -- can override base price stock_quantity INT , image_url TEXT ); The key insight? Keep the product metadata (description, care instructions, brand story) in the products table, but put all the sellable attributes in variants. This lets you run queries like: -- Find all size 28 jeans in "mid wash" under $80 SELECT p . name , v . color , v . wash , v . price , v . stock_quantity FROM products p JOIN variants v ON p . id = v . product_id WHERE p . category = &# 039 ; women - jeans &# 039 ; AND v . size = &# 039 ; 28 &# 039 ; AND v . wash LIKE &# 039 ; % mid %&# 039 ; AND v . price & lt ; 80 AND v . stock_quantity & gt ; 0 ORDER BY v . price ; For the frontend, I usually return a flattened structure: { "product": { "id": "abc -123 " , "name": "Classic Straight Leg Jean" , "description": "High-rise fit in stretch denim..." , "availableSizes": [ " 24 " , " 25 " , " 26 " , " 27 "
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Day 50 - How to Migrate Data from MySQL to ClickHouse®: A Step-by-Step Guide
Introduction As applications grow, traditional relational databases such as MySQL may struggle with analytical workloads involving millions of records and complex aggregations. While MySQL excels at Online Transaction Processing (OLTP), ClickHouse® is purpose-built for Online Analytical Processing (OLAP), enabling lightning-fast analytical queries on massive datasets. Migrating data from MySQL to ClickHouse® allows organizations to build high-performance reporting systems, dashboards, and real-time analytics without impacting transactional workloads. In this guide, you'll learn several approaches to migrate data from MySQL to ClickHouse®, along with their advantages, limitations, and ideal use cases. Why Migrate from MySQL to ClickHouse®? MySQL and ClickHouse® are designed for different workloads. Feature MySQL ClickHouse® Storage Model Row-based Columnar Best For Transactions (OLTP) Analytics (OLAP) Query Speed Fast for row lookups Extremely fast for large scans Aggregation Performance Moderate Extremely fast Scalability Primarily Vertical Optimized for analytical scaling Typical Use Cases Applications and transactional systems Reporting, dashboards, and analytics Migrating from MySQL to ClickHouse® makes sense when: Analytical queries are becoming slow in MySQL. You need real-time dashboards over large datasets. Reporting queries are impacting your production database. You regularly process millions or billions of rows. Migration Architecture MySQL │ ▼ Export / Synchronization │ ▼ Data Transformation │ ▼ ClickHouse® │ ▼ Dashboards / Analytics Migration Methods There are multiple ways to migrate data depending on your requirements. Method 1: CSV Export and Import (Recommended for Beginners) This is the simplest approach for performing a one-time migration of historical data. Step 1: Export Data from MySQL Run the following command inside MySQL: SELECT * INTO OUTFILE '/tmp/employees.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY ' \n ' FROM employ
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Gemma, the Epstein Files, and sandboxing cause a stir at the World's Fair
As the AI Engineer World’s Fair kicked off officially on Monday, the halls were filled for the...
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Co-locating Data and Application Code for a 4.5x Performance Gain
Modern web application architectures typically run each layer in its own process, like a NodeJS server and database both running in their own processes. They communicate via a network connection or localhost socket. This separation introduces protocol overheads, TCP stack latency, and data serialization/deserialization costs on every single query. Planck is designed around the concept of Zero-Distance Architecture that co-locates data and application code. It combines the database engine and a WebAssembly application runtime into a single, unified process. By running your application code directly inside the database process, database calls become direct in-memory function calls rather than network round-trips. This article provides a practical guide to getting started with Planck. We will look at the core toolchain, walk through setting up a self-contained local benchmark, compare its performance against a NodeJS, ExpressJS, MongoDB stack, and look at how to build more complex features. The Toolchain: Planck, planctl, and Workbench Running and managing a zero-distance app requires three main components. Planck itself is the core binary. It functions as both the storage engine (a WiscKey-style, LSM-tree-based engine) and the WebAssembly host. Instead of running a database in one process and your application server in another, you run a single Planck process. It loads your compiled WebAssembly application directly into its memory, running it in the same process space as the database. To manage this runtime, you use planctl. This is the command-line tool for developers. It handles the compilation of your code, packages it, and deploys it to the Planck host. It also allows you to perform database operations, like creating stores and defining indexes, export/import, backup/restore directly from your terminal. Finally, there is the Workbench. This is a web console that comes built into the platform. It provides a visual dashboard to monitor your applications, view databa
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Stop Guessing, Start Modeling: Relationships, Schemas & Joins in Power BI
A database without relationships is just a spreadsheet with delusions of grandeur. If you've ever stared at a Power BI report showing wrong numbers...totals that don't add up, filters that filter nothing, there's a good chance your data model was broken. Not a bug. Just two tables that should've been talking to each other… and weren't. This is your practical guide to data modeling, schemas, relationships, and joins in Power BI, what they are, how they connect, and how to stop getting burned by them. What Is Data Modeling and How Does It Work? Data modeling is the process of defining how your tables connect to each other inside Power BI's engine (called VertiPaq). Think of it like drawing a map between your tables, telling Power BI this column in Table A is the same thing as this column in Table B. When you load multiple tables into Power BI, it doesn't automatically know they're related. A Sales table and a Products table, sitting separately, can't filter each other. Data modeling builds the bridges. Power BI's model view lets you: Define relationships between tables Set cardinality and cross-filter direction Build star or snowflake schemas Create calculated columns and measures using DAX Under the hood, Power BI compresses and stores each column separately ( columnar storage ). Relationships are resolved in-memory at query time, which is why a well-structured model is blazing fast, and a messy one will bring your report to its knees. Key Concepts | Concept | What It Means | |--------------------------|-----------------------------------------------------| | Fact Table | Stores measurable events (sales, transactions, logs)| | Dimension Table | Stores descriptive context (products, customers) | | Primary Key (PK) | Unique identifier column in a dimension table | | Foreign Key (FK) | Column in a fact table referencing a PK in a dim | | Relationship | The defined link between a PK and FK across tables | | Cardinality | Describes how many rows on each side match | | Cro
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South Korea to spend $1T on more memory chip production and humanoid robots
South Korea targets physical AI lead and commercial humanoid robots by 2028.
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OCI Database Auto Backup Window Time Slots Reference
The Database resource in Oracle Cloud Infrastructure Database service provides an optional auto_backup_window option in its API during creation ( Terraform resource: oci_database_database ). The database resource can be used in an OCI Base DB system or Exadata Cloud VM Cluster pluggable database (PDB) for example. The time window enum value selected for initiating automatic backup for the database system is available in twelve two-hour UTC time windows as the following: Slot Description SLOT_ONE 12:00AM - 2:00AM UTC SLOT_TWO 2:00AM - 4:00AM UTC SLOT_THREE 4:00AM - 6:00AM UTC SLOT_FOUR 6:00AM - 8:00AM UTC SLOT_FIVE 8:00AM - 10:00AM UTC SLOT_SIX 10:00AM - 12:00PM UTC SLOT_SEVEN 12:00PM - 2:00PM UTC SLOT_EIGHT 2:00PM - 4:00PM UTC SLOT_NINE 4:00PM - 6:00PM UTC SLOT_TEN 6:00PM - 8:00PM UTC SLOT_ELEVEN 8:00PM - 10:00PM UTC SLOT_TWELVE 10:00PM - 12:00AM UTC Timezone used for the slots is always UTC regardless of the timezone used in the database. For example, if the user selects SLOT_TWO from the enum list, the automatic backup job will start in between 2:00 AM (inclusive) to 4:00 AM (exclusive) If no option is selected, a start time between 12:00 AM to 7:00 AM in the region of the database is automatically chosen. Reference Terraform resource: oci_database_database OCI API Reference: Database DbBackupConfig Safe harbor statement The information provided on this channel/article/story is solely intended for informational purposes and cannot be used as a part of any contractual agreement. The content does not guarantee the delivery of any material, code, or functionality, and should not be the sole basis for making purchasing decisions. The postings on this site are my own and do not necessarily reflect the views or work of Oracle or Mythics, LLC. This work is licensed under a Creative Commons Attribution 4.0 International License (CC-BY 4.0) .
科技前沿
Trump administration threatens 92 GW of new electricity supply with red tape
The Trump administration's moves threaten $121 billion in new solar and wind power, two energy sources that are the biggest contributors to new capacity in the U.S.
开源项目
Inside the Advisory Database and what happens when vulnerability volume breaks records
The GitHub Advisory Database is processing more vulnerability reports than ever before. Here's what's driving the surge, how we're responding, and how the community can help. The post Inside the Advisory Database and what happens when vulnerability volume breaks records appeared first on The GitHub Blog .
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Inside Target’s LLM-Based System for Semantic Matching in Marketing Forecast Pipelines
Target built a generative AI system to improve marketing campaign forecasting by retrieving and ranking similar historical campaigns. Using embeddings, vector search, and LLM ranking, it replaces rule-based workflows. Evaluation shows 75% top-1 and 100% top-3 coverage. The system reduces manual effort, improves consistency, and uses feedback loops to refine retrieval using campaign outcomes. By Leela Kumili
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How to Fix Excel CSV Date Import Problems (US / UK Format Guide)
You export a CSV from a UK system and double-click it in US Excel — 28/05/2026 suddenly looks like May 28, or something even stranger. The file isn't corrupt. Excel is guessing your date format based on your computer's locale. This short guide covers why that happens, how to import CSV correctly, and how to batch-fix dates that are already wrong. For the full walkthrough with examples, see the official guide: How to Fix Excel CSV Date Import Problems . Why Excel breaks CSV dates A CSV is plain text. It does not store whether a value is a date or a string. When you double-click to open, Excel parses using your regional settings: US Excel: MM/DD/YYYY UK / Europe: DD/MM/YYYY Dates like 03/04/2025 are the most dangerous — both parts are ≤ 12. US Excel may read April 3; UK Excel reads March 4. Excel won't warn you. Other common traps: Dates exported as serial numbers (e.g. 44927 ) Two-digit years triggering century guesses Re-saving as CSV destroys formats a second time The right way: don't double-click the CSV Open Excel first — don't double-click the .csv file Data → Get Data from Text/CSV (older Excel: Data → From Text) Set date columns to Text if you need to preserve the original string Confirm the source region (US / UK), then convert to a single format For team data exchange, agree on ISO 8601: YYYY-MM-DD in your schema — unambiguous, sorts correctly as text, and works in JSON APIs and databases. Ambiguous value US reads as UK reads as Safe format (ISO) 03/04/2025 2025-04-03 2025-03-04 Confirm source region 28/05/2026 — 2026-05-28 2026-05-28 05/28/2026 2026-05-28 — 2026-05-28 Already broken? Fix dates in the browser (no server upload) I built a free tool cluster on FormatList — everything runs locally in your browser : 1. Date Format Fixer — bulk repair Paste a date column or upload .csv / .txt Ambiguous rows highlighted; optional US / UK preference Export ISO / US / UK or download a fixed CSV Best for: normalizing a whole column to ISO before a database or API imp
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When to denormalize, when to join: A ClickHouse guide (2026)
Denormalization has been the standard approach to analytical data modeling for good reason. Moving joins, lookups, and business rules out of query time and into ingestion gives you the fastest possible reads for a known access pattern. For most of the past decade, it was often the practical default for latency-sensitive analytics. Earlier columnar engines and distributed query processors could execute joins, but many workloads paid for them through higher latency, higher compute cost, spill-to-disk, or distributed coordination overhead. That constraint has loosened. Modern columnar databases with advanced join algorithms have reduced the cost of runtime joins enough that normalization is now a genuinely viable option for many analytical workloads. Denormalization still delivers faster reads, but normalization can bring operational benefits: simpler pipelines, flexible schemas, and cleaner governance. Engineers can now make the decision based on their actual workload characteristics, rather than being forced into one approach by engine limitations. This guide is a decision framework for making that choice in ClickHouse. It starts with why denormalization became the default, explains what has changed in join performance, then compares the tradeoffs on both sides so you can decide where to denormalize, where to join, and where to use ClickHouse primitives that bridge the gap. For a broader evaluation framework covering latency, concurrency, ingest throughput, SQL flexibility, and cost across real-time OLAP options, see our guide to choosing a database for real-time analytics in 2026 . For a deeper comparison of how ClickHouse executes star schema joins against Druid, Pinot, and cloud DWHs, see our star schema and fast joins guide . TL;DR Denormalization and normalization are both valid modeling strategies. The right choice depends on your workload. Denormalization's tradeoffs are primarily operational : pipeline complexity, write-path overhead, data freshness lag, back
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Connecting the Dots: Understanding Database Relationships and SQL Joins
Have you ever wondered how apps like university portals know which courses a student is enrolled in, or how they pull up an instructor's full schedule in seconds? The answer lies in database relationships - one of the most important concepts in backend development. In this article, we'll explore: What database relationships are and why they matter The three types of relationships: One-to-One, One-to-Many, and Many-to-Many How relationship schemas work (primary keys, foreign keys) How SQL Joins let you pull connected data from multiple tables To keep things grounded, we'll use one running example throughout: a University Management System . By the end, you won't just understand the theory, you'll see exactly how these concepts connect in a real-world scenario. What Are Database Relationships? A database relationship defines how data in one table connects to data in another. Instead of storing the same information repeatedly, relational databases organize data into separate tables and link them using keys . Think about our university system. We have a table for students and another for courses . A student can enroll in multiple courses, and each course can have many students. Rather than storing a student's full details on every course record, we store the student's info once and create a relationship between the two tables. This keeps data clean, reduces duplication, and makes updates easy. If a student's email changes? Update it in one place - done. Here's a simple visual of what that looks like: +------------------+ +------------------+ | Students | | Courses | +------------------+ +------------------+ | student_id (PK) | | course_id (PK) | | name | | title | | email | | credits | +------------------+ +------------------+ \ / \ / \ / Enrollments (links students ↔ courses) Now let's look at the three types of relationships you'll encounter. Types of Database Relationships 1. One-to-One (1:1) Each record in Table A matches exactly one record in Table B and vice versa