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PostgreSQL ERROR: deadlock detected — What It Means and How to Fix It

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If you’ve ever seen the error "ERROR: deadlock detected" in PostgreSQL, chances are your application suddenly failed in production. This error is confusing, hard to reproduce, and often misunderstood. In this article, we’ll explain what it really means and how to fix it properly. What Is a Deadlock? A deadlock happens when two (or more) transactions block each other forever. Each transaction holds a lock and waits for another lock that will never be released. Simple Example Transaction A locks row 1 and waits for row 2 Transaction B locks row 2 and waits for row 1 PostgreSQL detects this situation and aborts one transaction to prevent an infinite wait. The Exact Error Message ERROR: deadlock detected DETAIL: Process 12345 waits for ShareLock on transaction 67890; blocked by process 54321. This means PostgreSQL killed one transaction to resolve the deadlock. Why Deadlocks Happen in PostgreSQL 1. Different Order of Updates The most common cause ...

Why Indexes Sometimes Make Queries Slower

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Indexes are often seen as the ultimate solution to slow SQL queries. While they usually improve performance, there are situations where indexes can actually make queries slower. Understanding when and why this happens is critical for building fast and scalable databases. In this article, we’ll explore why indexes sometimes hurt performance and how to avoid common mistakes. How Indexes Are Supposed to Help Indexes allow the database to quickly locate rows without scanning the entire table. In general, indexes help when: Tables are large Queries filter on selective columns Indexes are well maintained But this is not always the case. Reason 1: Low Selectivity Indexes An index on a column with very few unique values is often useless. Example CREATE INDEX idx_users_active ON users(active); If most rows have active = true , PostgreSQL may choose a sequential scan instead of the index. In some cases, forcing index usage adds unnecessary overhead. Reas...

The Power of Internal Linking for Developers

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As developers, we often focus on clean code and efficient algorithms, but if you're running a tech blog, there's one "algorithm" you can't ignore: Google's search ranking . One of the simplest yet most effective ways to boost your site's authority is through Internal Linking . Why Internal Linking Matters Internal links are hyperlinks that point to another page on the same domain. They help search engines understand the structure of your blog and establish a hierarchy of information. For a "Byte Nomad," this means keeping readers engaged with your content longer, reducing bounce rates. Boost Your Productivity While You Browse Contextual linking is the best way to implement this. For example, while you are reading about SEO or workflow optimization, you might need a tool to manage your time. We actually built a custom Minimalist Pomodoro Timer specifically for our community to use during deep work sessions. ...

Flutter Push Notifications V2: Advanced Patterns, Security, and Troubleshooting

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In our previous post , we compared the heavyweights of the notification world: FCM, OneSignal, and AWS. But once you’ve picked your champion, the real work begins. If you’ve ever wondered why your images don't show up on iOS, or why your app doesn't trigger logic when tapped while terminated, you're in the right place. Welcome to Part 2 of the ByteNomads guide to Push Notifications. Today, we’re moving beyond the "Hello World" ping and diving into advanced implementation patterns for 2026. 1. Data vs. Notification Payloads: The Isolate Trap The biggest mistake Flutter developers make is confusing notification messages with data messages. Notification Messages: Handled by the OS. If the app is in the background, the OS displays the tray icon and text automatically. Your Flutter code doesn't even run until the user taps it. Data Messages (Silent Pushes): Handled by your app. This triggers a background isolate. You...

The Ultimate Guide to Flutter Push Notifications in 2026: From Firebase to AWS and Beyond

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In the early days of mobile development, push notifications were a "nice to have" feature—a simple ping to tell a user they had a new message. Fast forward to 2026, and the landscape has shifted dramatically. In the Flutter ecosystem, notifications are now sophisticated instruments of engagement, capable of updating real-time data, triggering background tasks, and even displaying interactive widgets on a locked screen. As a Flutter developer, you are no longer just asking "How do I send a message?" but rather "How do I manage notification state, handle high-frequency updates, and ensure delivery across fragmented OS versions?" Today, we’re diving deep into the tech stack that makes this possible. 1. Understanding the Plumbing: The Gateway Architecture Before we pick a service, we must understand the "physics" of push notifications. No matter which Flutter plugin you use, your notification will eventually travel through one of t...

How to Debug Slow SQL Queries Step by Step

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Slow SQL queries are one of the most common causes of performance problems in backend applications. The challenge is not just knowing that a query is slow — it’s understanding why . This step-by-step guide shows how to debug slow SQL queries in a systematic and practical way, using PostgreSQL as an example. Step 1: Identify the Slow Query The first step is knowing which queries are slow. Common ways to identify slow queries: Application logs Database monitoring tools User reports In PostgreSQL, you can enable slow query logging to capture problematic queries. Step 2: Reproduce the Query Once you have the slow query, run it manually in the database. SELECT * FROM orders WHERE user_id = 42; Always test queries using realistic data volumes. Queries that are fast on small datasets may fail at scale. Step 3: Use EXPLAIN The EXPLAIN command shows how PostgreSQL plans to execute a query. EXPLAIN SELECT * FROM orders WHERE user_id = 42; This output sh...

Why PostgreSQL Queries Become Slow Over Time (And How to Fix Them)

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PostgreSQL is known for being reliable and powerful. Yet, many developers experience the same issue: queries that were once fast become slower over time. This usually doesn’t happen by accident. In most cases, performance degradation has clear and fixable causes. In this article, we’ll explore why PostgreSQL queries become slow over time and what you can do to fix them. Why PostgreSQL Performance Degrades PostgreSQL databases evolve constantly: Tables grow Indexes become outdated Data distribution changes If the database is not maintained, query performance naturally suffers. Problem 1: Missing or Inefficient Indexes Indexes are critical for performance. Without them, PostgreSQL must scan entire tables. Example of a Slow Query SELECT * FROM orders WHERE user_id = 42; If user_id is not indexed, PostgreSQL performs a sequential scan. Solution CREATE INDEX idx_orders_user_id ON orders(user_id); Indexes dramatically reduce query time for large ta...

Advanced n8n Workflows: Building an Automated Incident Response Email System

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Most people use n8n for simple data transfers. But the real power of this tool lies in its ability to handle complex logic and multi-step integrations. Today, we’re building a Self-Healing Notification System : an automated workflow that identifies a code culprit after a crash and sends a detailed technical report via email. The Logic Flow Our workflow doesn't just send an email; it enriches data. Here is the pipeline: Webhook: Receives an error payload from your production server. HTTP Request (GitHub API): Fetches the last commit metadata for the failing service. Function Node: A custom JavaScript block to merge error logs with developer info. HTML Template: Generating a responsive, technical email body. SMTP/SendGrid: Dispatching the high-priority alert. 1. Handling the Webhook Payload Your server sends a POST request with the service_name and error_stack . In n8n, we use the Webhook Node . Ensure you set the HTTP Method to POST and the...

AI-Powered Product Owner: Automating Jira User Stories with Python and OpenAI

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The role of a Product Owner is often bogged down by the manual task of converting vague ideas into structured tickets. What if we could automate the "thinking" process? In this article, we will build a Technical AI Agent that takes a simple prompt and transforms it into a professional User Story directly inside Jira . The Architecture: How the AI Agent Works Our solution consists of three main layers: the Intelligence Layer (OpenAI), the Integration Layer (Python + Jira API), and the Project Management Layer (Jira Software). 1. Setting Up the Jira API To communicate with Jira, you need an API Token. Go to your Atlassian account security settings and generate one. You will need your Domain , Email , and the Token . # Requirements pip install jira openai 2. The Intelligence Layer (The "PO Prompt") The secret to a good AI Product Owner is the System Prompt . We need to instruct the AI to output data in a specific format (Gherkin or standard User Sto...

API Security Handbook: How to Prevent the Top 5 Most Common Attacks

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Building an API that works is easy. Building an API that is secure is a completely different challenge. With the rise of microservices, APIs have become the primary target for hackers. In this guide, we will explore the most critical security flaws and, more importantly, how to fix them before they are exploited. 1. Broken Object Level Authorization (BOLA) BOLA is currently the #1 threat to APIs. It occurs when a user can access or modify data belonging to another user just by changing an ID in the URL. The Attack: A user logged in as ID 123 sends a request to GET /api/orders/456 and successfully sees someone else's order. The Fix: Never trust the ID provided in the request alone. Always validate that the resource belongs to the authenticated user in your database query. // BAD: Trusting the URL ID var order = db.Orders.Find(id); // GOOD: Checking ownership var userEmail = User.Identity.Name; var order = db.Orders.FirstOrDefault(o => o.Id == id && o.UserE...