We opened Chapter 1 with a single line, SELECT * FROM users WHERE id = 1 . For that line to leave the client and come back as a result row, the PostgreSQL backend went through five stages. First it decided which processing path the message should take; then the parser and analyzer turned the text into a tree and gave it meaning from the catalog. The rewriter expanded views and injected policies to transform the tree, the planner weighed the possible execution paths by cost and picked the cheapest one, and the executor followed that plan, pulling up one tuple at a time and sending them back to the client. Chapter 1 was a story about how a query is processed . What tree a given SQL becomes, what plan it turns into, in what order it runs. From start to finish, a chain of logical transformations. But what every one of those stages ultimately deals with is data. The executor pulls up tuples, yet where on disk those tuples lie and in what shape, how they come up into memory, Chapter 1 never asked. When the planner judged an index scan cheaper than a sequential scan, it never opened up what that index physically is. Chapter 1 followed only the logical journey of a query, leaving untouched the substance of the data that journey stands on. Chapter 2, Storage & Access Methods, opens up that substance. In what unit data sits on disk (page), where disk and memory meet (buffer manager), where and how a row survives (heap), and how that row is found quickly (B-tree and the specialized indexes). The very tuple the planner weighed by cost and the executor pulled up in Chapter 1, where it actually came from and how it came to be there, is what Chapter 2 reveals. If Chapter 1 was the logical life of a query, Chapter 2 is the physical dwelling of data. We now look at how the data a query reaches for actually lives on disk.

A scan node sits at the leaf of the tree and pulls rows from a single table. A join node sits in the middle and brings together the rows that its two children send up. It takes one row from users , one row from orders , checks whether they belong to the same user, and if they match, emits the combined row. PostgreSQL has three nodes for this one job: NestLoop, HashJoin, and MergeJoin. The reason a single task splits into three nodes is much like the reason scans did. There is more than one way to find matching pairs from two inputs, and which way is cheapest depends on the size of the inputs and the shape of the join condition. Deciding which way is cheapest, by costing the alternatives, was the planner's job in an earlier chapter. This section looks at what those three nodes actually do when they execute. Given the same two tables, the three find matches in completely different ways, and that difference in approach is exactly what tells them apart. How the three nodes route requests All three join nodes are internal nodes with two children. One child is called the outer, the other the inner. All three run on the Volcano model's pull framework: when the parent asks for the next row, the join node takes rows from its two children, builds one matched row, and sends it up. The only difference is the order and manner in which it routes pull requests to its two children. NestLoop pulls the inner from the start all over again for each outer row it receives. HashJoin slurps the inner in one pass to build an index in memory, then takes outer rows one at a time and probes that index. MergeJoin, on the assumption that both sides are sorted in the same order, advances both sides one step at a time in lockstep. NestLoop: rescan the inner for every outer row The simplest method is NestLoop. As the name says, the loops are nested. The outer loop takes one row from the outer; the inner loop scans the inner from beginning to end, looking for inner rows that match that outer row. Wh

You've probably seen that trending post — "I Asked AI to Write My Commit Messages and It Was Embarrassing." Same. But instead of accepting embarrassing output, I fixed it. Here's the thing: the problem isn't AI writing commit messages. The problem is how you ask it. One clear system prompt + the actual diff = surprisingly good results. The Setup No new packages. No API key. If you have Claude Code , you're already set. #!/usr/bin/env python3 import subprocess SYSTEM = ( " You are a git commit message generator. " " Output ONLY the commit message — no explanation, no markdown, no quotes. " " Follow Conventional Commits: type(scope): subject. " " Types: feat, fix, docs, style, refactor, test, chore. " " Subject: imperative, lowercase, max 72 chars. " ) diff = subprocess . check_output ([ " git " , " diff " , " --staged " ], text = True ) if not diff . strip (): print ( " Nothing staged. Run `git add` first. " ) raise SystemExit ( 1 ) msg = subprocess . check_output ( [ " claude " , " -p " , SYSTEM + " \n\n " + diff ], text = True , ). strip () print ( msg ) That's it. 20 lines. Uses the claude CLI under the hood — no API key, no config, just your existing Claude Code OAuth session. Why It Works The system prompt does the heavy lifting. Three constraints: Output ONLY the commit message — no preamble, no explanation Follow Conventional Commits — feat , fix , chore , etc. max 72 chars — keeps it readable in git log The diff is the context. You're not asking "write a commit message". You're asking "given these exact changes, what happened?" That's a much more answerable question. Usage # No setup needed if you have Claude Code. Just: git add . python /path/to/git_commit.py # → feat(server): add AI commit message generator via Claude CLI Or wire it into a git alias: git config --global alias.ai '!python /path/to/git_commit.py' # git ai The Results Before: update stuff fix bug WIP added the thing After: feat(api): add generate_commit_message tool to MCP server fix(auth): ha

Gelişmiş Veri İşleme (Python) Sıralama, Filtreleme ve Arama – Profesyonel Veri Manipülasyonu Rehberi Python’da veri işleme, sadece döngülerden ibaret değildir. Modern Python yaklaşımı; fonksiyonel programlama araçları , yüksek seviyeli built-in fonksiyonlar ve lambda ifadeleri ile daha kısa, daha okunabilir ve daha performanslı çözümler üretmeyi hedefler. Bu bölümde dört kritik alanı derinlemesine inceleyeceğiz: sorted() ile gelişmiş sıralama lambda ile karmaşık veri yapıları üzerinde sıralama filter() ve map() ile fonksiyonel veri dönüşümü any() ve all() ile toplu doğrulama (validation) Her bölümde gerçek dünya senaryoları ve hands-on örnekler olacak. 1. sorted() Fonksiyonu — Gelişmiş Sıralama Motoru 1.1 Temel Yapı sorted ( iterable , key = None , reverse = False ) Parametreler: iterable: Liste, tuple, set vb. key: Sıralama kriteri (fonksiyon) reverse: True → büyükten küçüğe 1.2 Basit Sıralama ```python id="s1" sayilar = [5, 1, 9, 3, 7] sonuc = sorted(sayilar) print(sonuc) --- ## 1.3 Ters Sıralama ```python id="s2" sayilar = [5, 1, 9, 3, 7] print(sorted(sayilar, reverse=True)) 1.4 Tuple Sıralama ```python id="s3" veri = (10, 5, 20, 15) print(sorted(veri)) --- ## 1.5 String Sıralama (ASCII mantığı) ```python id="s4" kelimeler = ["python", "ai", "data", "backend"] print(sorted(kelimeler)) 2. key Parametresi — Sıralamanın Beyni sorted() fonksiyonunun gerçek gücü burada başlar. 2.1 String Uzunluğuna Göre Sıralama ```python id="k1" kelimeler = ["python", "ai", "veri", "makineöğrenmesi"] sonuc = sorted(kelimeler, key=len) print(sonuc) --- ## 2.2 Sayıların Moduna Göre Sıralama ```python id="k2" sayilar = [10, 3, 7, 21, 14, 9] sonuc = sorted(sayilar, key=lambda x: x % 5) print(sonuc) 2.3 Tuple Sıralama (Gerçek Dünya) ```python id="k3" urunler = [ ("Laptop", 45000), ("Mouse", 500), ("Monitör", 12000) ] sonuc = sorted(urunler, key=lambda x: x[1]) print(sonuc) --- ## 2.4 Çok Katmanlı Sıralama Fiyat → sonra isim ```python id="k4" urunler = [ ("Laptop", 45000), ("Mouse", 500),

By the time 1.4 ends, the planner has produced one PlannedStmt. Inside it is an execution tree built from Plan nodes, frozen into a form you can follow step by step, something like "go into the primary key index on users, fetch the one matching row, then output that whole row." But that is still only a blueprint. Reading actual pages off disk, picking out the rows that match the condition, handing results back to the caller: none of that has happened yet. The stage that takes that blueprint and produces actual rows is the executor. The difference between the planner and the executor is the difference between deciding and doing. The planner was the stage that weighed "which index, in what order, with what join method" by cost and chose . The executor takes the chosen approach and carries it out as is . There is nothing left to choose. It just runs the nodes baked into the plan tree and pulls rows out of them. To run it, the executor takes the Plan tree it received and turns it into a PlanState tree. The Plan tree is the static blueprint the planner made, and it does not change during execution. But to actually run, each node needs state that changes as execution proceeds: which row it is reading now, whether the hash table is fully built, what tuple it has buffered from a child. So when execution begins, a PlanState tree with the exact same shape as the Plan tree is created. The blueprint Plan tree is left untouched, and the running state lives in that PlanState tree instead. How the executor produces result rows is the heart of the stage. The executor does not build the entire result set at once and stack it up. Instead, it asks the topmost node of the tree for "the next row," and that request travels down the tree to the leaves. When a leaf scan node reads one row from a page and passes it up to its parent, that row climbs up one level at a time through joins and filters until it reaches the top. The top sends that single row to the caller (the client, or the targe

Everything from 1.4.1 through 1.4.9 happened inside a single function, standard_planner() . Building paths, costing them, searching for a join order, estimating cardinality from statistics: all of it runs inside that one function. Yet PostgreSQL does not call standard_planner() directly. It puts another function, planner() , one step ahead of it, and has planner() call standard_planner() . And planner() can be made to call some other function instead of standard_planner() . That replacement is what the planner hook enables. When pg_stat_statements measures per-query planning time, or pg_hint_plan rewrites a plan according to hints, it all goes through this hook. Let's look at how PostgreSQL provides a way to observe or change planning behavior without touching a single line of the core, and how external code plugs into it. All planner() does is check the hook The body of planner() is essentially this. if ( planner_hook ) result = ( * planner_hook ) ( parse , query_string , cursorOptions , boundParams ); else result = standard_planner ( parse , query_string , cursorOptions , boundParams ); planner_hook is a global function pointer. Its default value is NULL , in which case standard_planner() is called right away. A plain PostgreSQL build always takes this path: planner_hook is empty, so the incoming query goes straight to standard_planner() . The key here is the type of planner_hook . typedef PlannedStmt * ( * planner_hook_type ) ( Query * parse , const char * query_string , int cursorOptions , ParamListInfo boundParams ); This signature is identical, down to the character, to that of planner() and standard_planner() . It takes the same Query and returns the same PlannedStmt (the execution plan). So external code only has to write a planner function matching this type and store its address in planner_hook . Let's call this function, written by external code to register in planner_hook , a custom planner function. The moment its address is stored, every planning reque

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I bombed a system design interview last year — not because I didn't know the architecture, but because I spent the first 5 minutes fighting Excalidraw. So I built SystemDesignBoard — a free, keyboard-first whiteboard specifically for system design interviews. What it does You open it, press a key, and start drawing. No account, no onboarding, no drag-from-a-sidebar friction. R → place a Service node C → place a Database/Cache/Queue A → connect two nodes N → open the scratchpad for scale math The features I'm most proud of Animated connectors that show communication type Instead of just drawing arrows, connectors visually encode how services talk: ⇄ sync — paired dashes (request + ACK) ≋ stream — near-solid fast line with glow (continuous pipeline) This matters in interviews — your interviewer can glance at your diagram and immediately understand the communication pattern. Cloud provider badges Tag any node as AWS (EC2, Lambda, RDS, S3), GCP (GKE, Cloud Run, Firestore), or Azure. Each subtype has its own icon. Trade-off logging Right-click any node → Log Trade-offs → attach your CAP theorem stance, consistency level, and scaling strategy directly to the component. Diagram-as-Code Type: [Mobile App] -> [API Gateway] [API Gateway] -> [Auth Service] [Auth Service] -> [Users DB] [Feed Service] -> [Posts DB x3] [Feed Service] -> [Redis Cache] Hit Apply — it auto-lays out the whole architecture in seconds. Export to animated GIF Export your diagram as a GIF that shows live traffic flow animations. Great for sharing after an interview or in a design doc. Tech stack React + TypeScript + Vite @xyflow/react (ReactFlow v12) for the canvas Zustand + Immer for state with full undo/redo html-to-image + gifshot for PNG/GIF export It's free and open No signup required. Works entirely in the browser. Free during beta. 👉 systemdesignboard.com Would love feedback — especially from anyone who's done system design interviews recently. What's missing? What's annoying? Drop a comment below

This is a submission for the June Solstice Game Jam Solstice Arcade: Festival of Light – Submission for June Solstice Game Jam 2026 Play Solstice Arcade Now! setuju / Solstice-Arcade-Festival-of-Light Game Solstice Arcade Solstice Arcade: Festival of Light A highly polished, multi-genre retro web game built for the June Solstice Game Jam 2026 . Experience interactive themes combining Solstice, Pride Month, Juneteenth, Alan Turing's cipher heritage, World Cup football soccer, and international Sushi Day. Collect all 14 Starlight Fragments , solve hidden ciphers, and challenge other operands in the global leaderboard! 🎮 Game Modes 1. Spectrum Architect (Solstice + Pride + Turing) Unravel ciphers using an interactive enigma-like rotor device. Experience high-fidelity color spectrum mappings where cryptography meets chromatic light calibration. Goal: Uncover 30 distinct color-clue riddles. 2. Solstice Sumo (Pride + World Cup) A hyper-fast physics canvas battle in a vibrant circle. Push your opponent out of bounds or secure celestial light balls. Goal: Outmaneuver opponents, maintain circular leverage, and trigger high-speed dashes. 3. Echoes of Galveston (Juneteenth + Rhythm) An interactive synchronized Web Audio beat-tapping rhythm game commemorating emancipation. High-density audio… View on GitHub 🎮 Game Description "Solstice Arcade: Festival of Light" is an interactive web experience celebrating humanity's diversity under the light of the longest day. Serving as an anthology of 5 mini-games, users solve puzzles and complete challenges honoring distinct cultural, historical, and mathematical milestones around the solstice, including Juneteenth, international sushi day, the World Cup, and Alan Turing's monumental contributions. ✨ Key Features 5 unique mini-games (Spectrum, Galveston, Sumo, ShadowChef, LongestSecond). Cinematic historical intros preceding each game mode. Hidden tasks & Starlight Fragments designed to reward exploratory interactions. Easter egg "The Shad

In the earlier posts of this series, we looked at practical query tuning tips and how to read and interpret query plans . A recurring theme in both was: "add an index here." But "add an index" is a bit like saying "use the right tool" — the interesting part is which one. PostgreSQL ships with several index types, each tuned for a different kind of data and query. Picking the wrong one means PostgreSQL quietly ignores your index and goes back to a sequential scan. In this post, we'll walk through the main index types, when each shines, and the special index variations (composite, partial, covering, expression) that often matter more than the type itself. Setting the Scene: Schema and Sample Data We'll reuse the same schema from the previous posts, with one small addition — a metadata JSONB column and a tags array on orders , so we can explore the more exotic index types. CREATE TABLE customers ( id SERIAL PRIMARY KEY , customer_name VARCHAR ( 255 ), email VARCHAR ( 255 ), created_at TIMESTAMPTZ DEFAULT NOW () ); CREATE TABLE orders ( id SERIAL PRIMARY KEY , customer_id INT REFERENCES customers ( id ), order_date TIMESTAMPTZ DEFAULT NOW (), total_amount NUMERIC ( 10 , 2 ), status VARCHAR ( 20 ), tags TEXT [], metadata JSONB ); -- Insert sample customers INSERT INTO customers ( customer_name , email ) SELECT 'Customer ' || i , 'customer' || i || '@example.com' FROM generate_series ( 1 , 1000000 ) AS s ( i ); -- Insert sample orders INSERT INTO orders ( customer_id , order_date , total_amount , status , tags , metadata ) SELECT ( RANDOM () * 1000000 ):: INT , NOW () - interval '1 day' * ( RANDOM () * 365 ):: int , ( RANDOM () * 500 + 20 ), ( ARRAY [ 'pending' , 'shipped' , 'delivered' , 'cancelled' ])[ FLOOR ( RANDOM () * 4 + 1 )], ARRAY [( ARRAY [ 'gift' , 'priority' , 'fragile' , 'bulk' ])[ FLOOR ( RANDOM () * 4 + 1 )]], jsonb_build_object ( 'channel' , ( ARRAY [ 'web' , 'mobile' , 'store' ])[ FLOOR ( RANDOM () * 3 + 1 )]) FROM generate_series ( 1 , 1000000 ) AS s ( i

The Playwright Playbook — Part 7: The CI/CD Setup Nobody Shows You "A test suite that only runs on your laptop isn't a test suite. It's a hobby." Six parts in, we have a serious framework. POM-based UI tests. Network interception. Multi-user contexts. A full API testing layer. Visual regression across four viewports. A complete debugging toolkit. Now it needs to run automatically. On every pull request. On every merge. On every deployment. Without you touching it. Most CI/CD tutorials for Playwright show you this: # The "tutorial" version everyone copies - run : npx playwright test That's not a CI setup. That's a shell command in a YAML file. A real production CI/CD pipeline for Playwright has: Sharding — split tests across multiple machines and finish in a fraction of the time Browser matrix — Chromium, Firefox, WebKit in parallel Docker — identical environment on every machine, every time Artifacts — HTML report, traces, screenshots, videos — downloadable from every run Failure notifications — your team knows within seconds, not the next morning Separate VRT workflow — visual regression on its own cadence, not blocking every PR Environment-specific pipelines — staging vs production, different configurations Let's build all of it. 🎯 🏗️ Where We Left Off After Part 6, our full project structure is: playwright-playbook/ ├── tests/ │ ├── auth/login.spec.ts ✅ Part 1 │ ├── tasks/task-management.spec.ts ✅ Part 1 │ ├── network/ ✅ Part 2 │ ├── multi-user/ ✅ Part 3 │ ├── multi-tab/ ✅ Part 3 │ ├── api/ ✅ Part 4 │ ├── visual/ ✅ Part 5 │ └── debug/trace-examples.spec.ts ✅ Part 6 ├── pages/ │ ├── LoginPage.ts ✅ Part 1 │ ├── TaskPage.ts ✅ Part 1 │ └── DashboardPage.ts ✅ Part 3 ├── api/ │ ├── TaskApiClient.ts ✅ Part 4 │ └── AuthApiClient.ts ✅ Part 4 ├── fixtures/ │ ├── auth.fixture.ts ✅ Part 1 │ ├── tasks.json ✅ Part 2 │ ├── empty-tasks.json ✅ Part 2 │ ├── tasks-har.har ✅ Part 2 │ ├── multi-user.fixture.ts ✅ Part 3 │ └── api.fixture.ts ✅ Part 4 ├── scripts/ │ └── record-har.ts ✅

I rebuilt StrictBlock (my app) from the ground up. StrictBlock is an iPhone app blocker and focus app designed to help people stop procrastinating, protect deep work, and build better focus habits. For this relaunch, I did not want to just “refresh the UI.” I wanted to redesign the full product experience around one question: How can I make starting a focus session feel simple, strict, and useful? The new version focuses on reducing friction. Users can create focus profiles for study, work, sleep, deep work, or Pomodoro sessions, then start blocking distracting apps and websites with less setup. I also redesigned the app around accountability. StrictBlock now includes streaks, trophies, weekly reports, widgets, session journaling, and consequences for ending sessions early. As a developer, this redesign was a good reminder that productivity apps are not only about features. They are about behavior. The UI, the flow, the defaults, and the friction all shape whether someone actually stays focused. StrictBlock is now live with a complete redesign. Would love feedback from other builders, iOS devs, and product engineers. Try it here: Download strictblock on appstore