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Defeating the Multi-Tenant SaaS Concurrency Trap in PostgreSQL
Most backend engineers implement multi-tenant quota checks using a standard "read-then-write" pattern. In production, this pattern is highly unsafe: SELECT grading_scans_remaining FROM profiles; If greater than 0, execute the application logic. UPDATE profiles SET grading_scans_remaining = grading_scans_remaining - 1; Under high volume or rapid concurrent requests, two independent processes will read the exact same balance before either one deducts usage. This race condition allows multi-tenant users to bypass your billing gates entirely. To solve this, you have to bypass the frontend and application-level checks, enforcing an atomic database operation that serializes the row update first. I have open-sourced a reference framework that outlines explicit subscription enums, core multi-tenant schemas, and a native VS Code / Cursor snippets configuration to speed up your local database modeling. 📂 Check out the repository on GitHub: { https://github.com/dollykm49/PostgreSQL-SaaS-Multi-Tenant-Subscription-Architecture-reference-framework- } What's inside the repository: Strictly Typed Enums: Centralized business rules handled natively by the database engine. Granular Balance Tracking: Optimized data-layer mapping for profiles and reset states. postgres-saas.code-snippets Engine: A local IDE configuration file that lets you deploy this core schema straight from your code editor by typing pg- shortcuts. For teams building commercial applications looking to skip weeks of writing custom migrations, testing concurrency edge-cases, and debugging row-locking security rules, the repository also includes a link to the extended 28-page production system bundle. Feedback on the multi-tier validation parameters is highly welcome!
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Your LLM Fallback Probably Isn't a Fallback
At 04:00 UTC, every model call through our LLM gateway started returning HTTP 400. Not some calls. All of them. Our tier-1 CI gate flagged it, and the fix was committed at 04:26 UTC the same morning — about 26 minutes end to end. This is the post-mortem. What happened DeepSeek retired two API model names — deepseek-chat and deepseek-reasoner — at their V4 cutover around 2026-07-24 15:59 UTC. The replacements are deepseek-v4-pro and deepseek-v4-flash . Our gateway config still declared both retired names. Starting roughly twelve hours after the retirement, every model request routed through the gateway hit a 400 with the body: The supported API model names are deepseek-v4-pro or deepseek-v4-flash, but you passed . A live API check confirmed the shape of the cutover with four requests, same valid key: Model name Response deepseek-v4-pro HTTP 200 deepseek-v4-flash HTTP 200 deepseek-chat HTTP 400 deepseek-v4-pro-quantized HTTP 400 The two working names are the replacements. The two retired names — the ones our config referenced — returned 400. The fourth row is a name that does not exist at all, included because an earlier reading of a truncated error message had suggested it; shipping it would have left the platform broken. We'll come back to that. Why the fallback didn't help We had a fallback configured. Three separate model references in our policy config — the default CLI/workflow model, the chat model, and the shared fallback model — all pointed at the two retired names. All three lived under the same vendor and the same API key. When the primary call returned 400, the gateway tried the fallback. The log told the story in two adjacent lines: the 400 from the provider, and then Error doing the fallback: carrying the identical error. The fallback died in the same instant as the primary because it was the same thing wearing a different label. This is the structural problem. A fallback that shares a provider and an API key with its primary is not resilience. It protec
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You Might Not Need Kafka: Building a Job Queue with PostgreSQL
It's easy to reach for the popular tool before asking what your system actually needs. For job queueing, the usual advice is to use RabbitMQ or Kafka. The underlying burden of using these tools will be additional processes to deploy, monitor and reason about. But what if using your existing database is possible? I built a job queueing system with a PostgreSQL database that cleared the bar without adding infrastructure. The next question will be, does this solution meet the criteria of a job queue? A job needs a few things to execute properly within a system. It needs to be persistent, surviving unforeseen crashes. Jobs must not be processed more than once by workers; one job should be processed once by one worker. Also, a job's state has to be tracked through every step. A job state must show when it's pending, completed or failed. That's the bar any solution must clear. With the Postgres approach, persistence comes free. Jobs live in a table so when a worker dies mid-job, the job still exists in a row in the db. Whereas with in-memory queues, a crash loses everything still in memory. A broker like RabbitMQ has to be configured for persistence and if configured wrongly, jobs get lost. A database however is fundamentally built for durability. Now, let's say three workers poll the queue at the same instant and run the same query. They'll see the same pending job at the top and nothing stops them all from grabbing it. If that job is a payment, the customer gets charged three times for one service. All the workers successfully process the job with no indication of an error or alerts. This is the requirement that seems to demand a real message broker, and it's exactly where people assume a database can't compete. It can. Postgres has a specific tool for exactly this. The SQL clause FOR UPDATE is used to lock rows. This can be called on a job when a worker picks it up to process. By default other workers will get blocked during this process, they'll wait for the lock to r
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The Crash That Only Happened Sometimes — A SwiftUI Bug
This is a submission for DEV's Summer Bug Smash: Smash Stories powered by Sentry. I...
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Paramount/WBD merger delayed for months as states' lawsuit moves toward trial
“Halting this merger while our case proceeds is a critical victory," NY AG said.
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My idle ClickHouse was merging 11 million rows every 30 seconds
I run a small self-hosted observability tool on the cheapest VPS I could find on purpose: 2 cores, 2 GB RAM, 20 GB SATA SSD . It ingests errors, traces and metrics from two low-traffic sites of mine. The stack is three containers — a Go app, PostgreSQL, and ClickHouse. One evening docker stats showed ClickHouse sitting on 880 MB of its 1 GB limit and the box swapping, with basically zero events coming in. So I went looking for where the memory and disk had gone. The answer turned out to be a good lesson in how a database can spend almost all of its I/O talking to itself. 543 KB of my data, 579 MB of ClickHouse talking about ClickHouse First thing I checked: how much data had my app actually stored versus how much ClickHouse had stored about itself . My application database: 543 KB, 16k rows The system database: 579 MB, 46.3M rows Roughly a thousand to one. Disk was 12 GB used out of 20 — on a tool that had recorded half a megabyte of real telemetry. The culprit was ClickHouse's own system logs, several of which have no TTL by default and therefore grow forever: trace_log — 404 MB, 26M rows (the query profiler writes here; it's on by default, sampling once per second) asynchronous_metric_log — 16.6M rows text_log — 132 MB plus query_log , latency_log Only metric_log , processors_profile_log and part_log ship with a TTL. Everything else just accumulates. Then I looked at the insert rate over 30 seconds: trace_log — 227 rows/s asynchronous_metric_log — 157 rows/s text_log — 44 rows/s my application — about 5 rows/s 98.8% of all inserts were ClickHouse narrating its own internals. The part that's expensive beyond disk Here's the number that made me stop. Over the same 30 seconds: rows inserted : 16,222 rows merged : 11,007,643 That's a 1 : 678 ratio. For every row written, the engine rewrote 678 already-sitting rows. The mechanics: MergeTree drops every insert into its own data part, then merges parts into bigger ones so reads stay fast. When the table is small this is
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Inside LioranDB's Full-Text Search Segments
A normal secondary index can answer: status = "active" It cannot efficiently answer: documents containing "distributed database" LioranDB therefore has a dedicated text-segment architecture. Tokenization Text is split on non-alphanumeric characters. Depending on index options, tokens can be normalized to lowercase and filtered through stopwords. "Building Distributed Databases" becomes ["building", "distributed", "databases"] Segment contents A LioranDB text segment can contain several files and structures: Term dictionary Posting lists Document map Document-length norms Optional term positions Bloom filter Segment metadata A posting connects a term to the local documents containing it. "database" → [doc 2, doc 8, doc 19] Positions can record where the term appears inside each document. That enables more advanced query behaviour and phrase-aware features. Global and local document IDs Each segment assigns compact local IDs to its documents. A separate document map translates them back to global document IDs. This keeps postings smaller while preserving the external identity of the record. Bloom filters Each segment also maintains a Bloom filter for terms. Before reading a segment's postings, the query path can test whether the term might exist there. A negative answer is definitive. A positive answer means the segment may contain the term and should be checked. Query modes The text query layer supports modes such as: AND OR It also emits scored documents and metrics including: Query time Postings read Candidate documents Segments searched Full-text search is essentially a specialized database living beside the document database. Its data structures, compaction behaviour, scoring, and caching needs are different enough that treating it as a plain secondary index would be a mistake. Built by Swaraj Puppalwar under Lioran Group . Learn more: LioranDB Lioran Developer Solutions Lioran Group
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Memtables: The Fast Write Buffer Inside LioranDB
Disk structures are durable, but updating them for every write is expensive. LioranDB uses memtables to absorb writes before flushing them to the on-disk B+ tree. What is a memtable? A memtable is an ordered in-memory map. In LioranDB, each entry contains either: Value ( bytes ) or: Tombstone A tombstone represents a deletion. The memtable also tracks: Approximate memory usage Minimum LSN Maximum LSN Entry count Put count Delete count The write path A simplified write path looks like this: Application write ↓ WAL durability ↓ Mutable memtable ↓ Immutable memtable queue ↓ Background flush ↓ Disk B+ tree The active mutable memtable accepts new writes. When it crosses a size limit, the engine rotates it into an immutable memtable. That immutable table is no longer modified and can safely be flushed in the background. Why ordered maps? LioranDB uses an ordered map for memtable entries. This helps because the flush process can emit keys in sorted order, which is friendly to the B+ tree and bulk-write paths. It also simplifies range merging between: Mutable data Immutable data On-disk pages Backpressure Background flushing cannot be allowed to fall behind forever. LioranDB therefore tracks limits such as: Maximum immutable memtables Maximum immutable bytes Partition-wide queue limits Maximum writer stall duration If the disk cannot drain the backlog quickly enough, the foreground write path slows down. That may sound undesirable, but controlled backpressure is much safer than consuming memory until the process dies. A memtable is not merely a cache. It is a pressure valve between CPU-speed writes and disk-speed persistence. Without that valve, the engine would either become slow on every commit or dangerously accumulate unbounded work. Built by Swaraj Puppalwar under Lioran Group . Links: LioranDB Lioran Developer Solutions Lioran Group
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Inside LioranDB: Why the Storage Engine Speaks Bytes, Not JSON
Most developers think of LioranDB as a document database. Internally, however, its storage engine does not understand documents, objects, fields, or JSON. It understands only: table + key bytes + value bytes That separation is intentional. The architecture LioranDB is split into two major layers: Application ↓ Document DBMS ↓ Transactional key-value engine ↓ WAL, memtables, B+ tree, pager and disk The engine exposes operations such as: get ( table , key ) put ( table , key , value ) delete ( table , key ) scan ( table , range ) The DBMS layer then adds document-oriented features: Collections JSON encoding Queries Updates Secondary indexes Text indexes Transactions For example, a secondary index can be represented as: idx:status:active → document_id A text index can be represented as: inv:database → posting_list The storage engine does not need to know what status , active , or database means. It only stores ordered bytes. Why this matters This architecture keeps the core engine small and reusable. The engine focuses on difficult low-level concerns: Durability Page management Transactions Recovery Ordering Concurrency Range scans The DBMS focuses on application-level semantics. This also makes it possible to build different data models over the same engine in the future. A document database is therefore not one giant component. It is a collection of carefully separated layers. That separation is one of the most important architectural decisions inside LioranDB. LioranDB is being developed by Swaraj Puppalwar under Lioran Group . Learn more: LioranDB Lioran Developer Solutions Lioran Group
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As US weighs response to Chinese AI, industry urges against broad open-weight restrictions
AI companies including Nvidia and Mistral urge policymakers to avoid broad restrictions on open-weight AI models as Washington debates responses to Chinese AI and alleged model distillation.
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Temporal in Production: Sharp Edges & Good Practices
Originally published on nejckorasa.github.io . When a team moves from a monolith into microservices and event-driven, asynchronous systems, it inherits a class of problems that used to be someone else's: work that fails halfway through, steps that must not run twice, calls that return before the work is done. Temporal is a durable execution engine that handles a lot of this - you define a multi-step process, and it guarantees the process runs to completion even when workers crash in the middle. I've spent the better part of a decade building distributed systems in the money-movement core of banks - ledgers, payments, credit cards - a lot of it on Temporal, from short request-triggered workflows to ones that stayed open for weeks. This is the high-level guide I'd give a team making that jump: the principles worth internalising before you ship, not a full tutorial. Most of them aren't really about Temporal. They're the habits the async shift demands - Temporal just punishes you quickly when you skip one. Durable Execution: The Problem It Solves Distributed work fails in the middle. You call service A, it succeeds. You call B, it times out. The pod dies before C. Now you have half-finished work and no memory of how far you got. The usual fix is a pile of status columns, a cron job to find stuck rows, and retry logic hand-rolled for every step. Temporal's promise is that any process you start runs to the end. The runtime picture: there's a Temporal service (its own cluster), and your app runs worker processes that poll it and execute your code. As a workflow runs, Temporal records every step to an event history . If a worker dies, another picks the workflow up and replays that history to rebuild state, then carries on from where it left off, retrying anything that failed. The history is the source of truth, and it survives the crash. Most of the rules below fall out of that one fact. The Golden Rule: Workflows Decide, Activities Do There are two kinds of code in Tempora
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Own Your Pixels: Native Fidelity on Your Schedule
An iOS or Android update can change a screen you shipped without you changing a line of code. If your app builds its UI from UIKit, SwiftUI, Compose, or Material widgets, Apple or Google owns those widget implementations. Codename One does something different. It statically links our lightweight component implementation into your native app. The UI you test is the UI your users keep after the next OS update. An update can still break a platform API or permission contract, but it cannot swap our button implementation for a new one. What is Codename One? Codename One is an open-source framework for building native iOS, Android, desktop, and web apps from a single Java or Kotlin codebase. Learn more at codenameone.com . Lightweight does not mean a Java paint loop limping behind the platform. On iOS, components paint through our Metal pipeline. The moving Liquid Glass tab lens in this post is a Metal shader on the frame's existing command buffer, with no transfer of pixels back to the CPU. At the same time, last week's ParparVM work brought our ahead-of-time VM to geomean parity with warmed Java 25 across ten benchmarks. Six finished at or ahead of HotSpot. The tradeoff is that our UI does not inherit Apple's or Google's latest redesign for free. We have to study it, reproduce the parts that make sense, and test the result. That is work we take on so you can work on your app instead of working for the Apple and Google design teams. You decide when your app adopts a new look. The OS does not decide for you on upgrade day. The ParparVM and theme-fidelity branches ran in parallel. We wanted them in the same release, but each became too large to merge together safely. The fidelity work took longer. PR #5274 alone reports 53,000 additions across 1,147 changed files. Generated access registries, resources, screenshots, and native goldens account for much of that number, but the scale is still real. Five follow-up PRs fixed what the first pass exposed. Owning the component sta
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Grok 4.5 vs Claude Opus 4.8: Same Code, a Quarter of the Tokens?
xAI has a bold pitch for Grok 4.5: it codes about as well as Claude Opus 4.8, but does it with roughly a quarter of the tokens. That's not a "we're smarter" claim. It's a "we're just as good for far less money" claim, which in 2026 might matter more. Someone actually put it to the test, so let me walk through what the numbers say and why you should care. The claim and the pricing Grok 4.5 landed on July 8, 2026. xAI says it matches Opus 4.8 on coding while using about 4.2 times fewer output tokens to get there. The sticker price already favors Grok. It runs $2 per million input tokens and $6 per million output. Opus sits at $5 and $25. That's less than half the price on both sides before you even factor in the token efficiency. Stack the two together and the cost gap gets dramatic. What the benchmarks say The benchmarks mostly support the marketing, with a catch. On Terminal-Bench 2.1, which measures real command-line work, Grok 4.5 scored 83.3 percent to Opus 4.8's 78.9. But on SWE-Bench Pro, the harder test of fixing real open-source bugs, Opus still comes out ahead. So the honest read is not "Grok is better." It's "Grok is about as good, for a lot less." Different claim, and a more interesting one. The hands-on test Benchmarks are one thing, real work is another. The New Stack ran a head-to-head, giving both models the same three jobs in one real Rust project (the fd file-finder) inside Cursor, and tracked every token. I'm summarizing their results here, credit to them for actually measuring it. The three tasks were a bug fix, a multi-file refactor, and a feature build. The code both models produced was nearly interchangeable, so the story came down to tokens, time, and cost. On the small bug fix, Opus actually won. Both wrote an identical fix with all tests passing, but Opus did it faster and on fewer tokens. Grok's efficiency edge showed up on the bigger jobs. On the refactor, Grok used about 197K tokens versus Opus's 954K for the same result, roughly a fifth.
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Microsoft pressures LG into killing unwanted McAfee ads
Microsoft has intervened to stop Windows 11 users with LG monitors from being bombarded with annoying McAfee trial pop-ups. In response to complaints about the LG bloatware, Microsoft's Windows chief, Pavan Davuluri, said that LG has agreed to immediately disable the McAfee pop-up from its LG Monitor App Installer, and pledged that Microsoft will "keep […]
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How a Single beforeEach Killed Our CI for 36 Hours
Six failed CI runs. Thirty-six hours of GitHub Actions time. Every run timing out at exactly the 6-hour limit. The culprit was one line in tests/setup.js . The Setup We were building a multi-tenant platform with a PostgreSQL backend — around 76 database models handling everything from user accounts and billing to visitor logs and real-time notifications. The test suite had grown to roughly 1,140 test cases across 36 files. Standard stuff. CI ran on every PR. Tests passed locally. And then one day, CI just... never finished. The Anti-Pattern Here's what the test setup looked like: // tests/setup.js beforeEach ( async () => { const tableNames = await getTableNames (); // 76 tables await sequelize . query ( `TRUNCATE TABLE ${ tableNames . join ( ' , ' )} CASCADE;` ); }); The intent was clean isolation — every test starts with a blank slate. Reasonable in theory. Catastrophic in practice. The Math Do the multiplication: 76 tables × 1,140 tests = 86,640 TRUNCATE operations Each TRUNCATE TABLE ... CASCADE is not a cheap operation. PostgreSQL has to: Acquire exclusive locks on all referenced tables Walk the foreign key graph to find dependent tables Truncate each in dependency order Release locks With a moderately complex schema where most tables reference others (users → societies → members → invoices → payments → ...), a single TRUNCATE ... CASCADE on a central table can fan out into dozens of implicit truncations. Multiply that by 86,640 and you have a test suite that will never complete within any reasonable timeout. Why It Wasn't Caught Sooner Two reasons: 1. It used to be fast. When the suite had 50 tests and 20 tables, this pattern worked fine. 50 × 20 = 1,000 truncations — uncomfortable but survivable. Nobody noticed when the suite crossed a tipping point. 2. Local runs used a different database state. Locally, developers often ran a subset of tests with --grep or file-specific runs. The full suite was only ever run on CI, and CI was slow enough that most assumed i
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onPreviewKeyEvent vs onKeyEvent on Android TV: A Subtle D-Pad Bug
The bug report was simple: long-pressing the d-pad center button on a channel card should toggle the favorite — it wasn't working reliably. On some devices it fired once and stopped. On others it didn't fire at all on long-press. The fix was changing onKeyEvent to onPreviewKeyEvent in one Composable. The reason why is worth understanding. Background: Two Event Handlers in Compose Jetpack Compose exposes two modifier-level hooks for key input: Modifier . onKeyEvent { keyEvent -> .. . } Modifier . onPreviewKeyEvent { keyEvent -> .. . } They sound equivalent. They're not. The difference is where they sit in the event propagation chain . How Android TV Routes D-Pad Events When a user presses a key on a TV remote, Android routes the event through a dispatch tree: Activity └─ ViewGroup (root) └─ FocusedComposable └─ Child Composables The event travels down first (capture phase), then up (bubble phase): Capture (top → focused node): onPreviewKeyEvent handlers fire here, outermost first. Bubble (focused node → top): onKeyEvent handlers fire here, innermost first. onPreviewKeyEvent is the capture phase. onKeyEvent is the bubble phase. Why This Matters for Long-Press Android TV handles long-press recognition at the framework level. When you hold the d-pad center button: A KeyEvent.ACTION_DOWN fires immediately. If the key is held, the framework generates repeated ACTION_DOWN events at the key repeat rate. ACTION_UP fires when the button is released. The long-press callback that Compose's focus system uses for "confirm" actions (select, activate) consumes ACTION_DOWN during the bubble phase — specifically to prevent the holding action from also triggering the tap action. When the ChannelCard had a click handler wired for the primary action and onKeyEvent for the long-press toggle, the click handler's bubble-phase consumption of ACTION_DOWN was racing with the long-press handler. On some devices the click handler won, swallowing the event before the long-press code ran. The Fix
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Privacy-First Health: Running Llama-3 Locally on iPhone with MLX-Swift
In the age of "Cloud Everything," our most sensitive data—our heartbeat, our sleep cycles, our stress levels—often ends up on a server somewhere in Northern Virginia. But what if we could keep that data where it belongs? On your device. Today, we're diving deep into Edge AI and On-device LLMs . We will build a privacy-centric health coach that uses MLX-Swift to run Llama-3 directly on your iPhone's Apple Silicon. We’ll be pulling real-time Heart Rate Variability (HRV) data from the HealthKit API and generating semantic health summaries without a single byte ever leaving your phone. 🚀 Why Edge AI? 🛡️ When dealing with Private AI and sensitive medical metrics, the "Cloud-First" approach is a liability. By leveraging MLX-Swift and the Unified Memory Architecture of the A17 Pro/A18 chips, we achieve: Zero Latency : No round-trip to a server. Total Privacy : Your data stays in the Secure Enclave. Offline Capability : Health insights in the middle of the woods? Yes. The Architecture 🏗️ The data flow is simple but powerful. We fetch raw samples from HealthKit, preprocess them into a prompt-friendly format, and feed them into a quantized Llama-3 model managed by the MLX framework. graph TD A[iPhone HealthKit Store] -->|Fetch HRV Samples| B(Swift Data Controller) B -->|Normalize & Format| C{MLX-Swift Engine} D[Llama-3-8B-4bit Model] -->|Load Weights| C C -->|Local Inference| E[Neural Engine / GPU] E -->|Semantic Summary| F[SwiftUI Dashboard] F -->|User Feedback| A Prerequisites 🛠️ To follow this advanced tutorial, you'll need: Xcode 15.4+ and a physical iPhone (iPhone 15 Pro or newer recommended for 8GB+ RAM). MLX-Swift : Apple's framework for machine learning on Apple Silicon. Llama-3-8B (4-bit quantized) : To fit within the iOS memory footprint. HealthKit Permissions : Configured in your Info.plist . Step 1: Accessing HealthKit Data 💓 First, we need to grab that juicy HRV data. Heart Rate Variability is a key indicator of autonomic nervous system stress. import HealthKit c
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B+tree height after delete: PostgreSQL fast root
Many databases use B+tree indexes, but they all differ. It's a sorted structure. The leaf pages are logically sorted so that a specific key value belongs to one page. A lookup by value reaches a single leaf page and either directly finds an entry for that value or immediately knows there's no entry with that key. When a page becomes full, it is split into two pages, each covering its own dedicated range. To find the right page, an internal page holds the range of values for the pages below. This internal page can become full, and a new level is added above it. Finally, at the highest level, there's a single internal page that is the root. A lookup always starts at the root and goes down to the leaves, following the branches of internal pages. In a traditional B+tree lookup, the cost is proportional to the height of the tree because the search starts at the root and descends to a leaf: 1 page to read when all fits in one leaf that is also the root (0 levels of internal pages, total height is 1). With small keys, this level can typically index hundreds of rows. 2 pages to read when there's one root that can list all leaf pages (1 level of internal page, total height is 2). With small keys, this level can typically index tens or hundreds of thousands of rows. 3 pages to read when there's one level of branches under the root (so 2 levels of internal pages, total height is 3). With small keys, this level can typically index millions of rows. This means that finding one key within ten million rows may require traversing 3 index pages, where most of them are probably in cache given the small number of branches compared to the leaves. For a given index size, whatever the value you are looking for, it's always the same number of pages to read because the index is balanced (the commonly accepted meaning of the B in B+tree). This property is maintained because any page can split, but only splitting the root adds another level. I've described how the height of an index can incr
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Microsoft responds to LG monitors installing McAfee ads on Windows
App is installed through Windows Update when certain LG monitors connect to a PC.
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How I replaced if statements with a Dictionary delegate in C#
Let's say you need to implement a feature that returns a different package based on the user-provided coupon code. So you start with a model: public record Package { public int Id { get ; set ; } public string Name { get ; set ; } public double Price { get ; set ; } } And you write a function that returns a different package based on the coupon code: private static Package GetPackageFromCoupon ( string coupon ) { if ( coupon == "ABC" ) { return new Package { Id = 1 , Name = "PS5 Controller" , Price = 50.00 }; } if ( coupon == "EBC" ) { return new Package { Id = 2 , Name = "Iphone X" , Price = 200.00 }; } if ( coupon == "DDD" ) { return new Package { Id = 3 , Name = "X7 Mouse" , Price = 20.00 }; } return new Package { Id = 1000 , Name = "Soda" , Price = 1.00 }; } And invoke it from your main method: internal class Program { static void Main ( string [] args ) { var package = GetPackageFromCoupon ( "ABC" ); Console . WriteLine ( package ); Console . ReadLine (); } } Quick test Provide expected parameters and inspect the results. "ABC" => Package { Id = 1 , Name = PS5 Controller , Price = 50 } "EBC" => Package { Id = 2 , Name = Iphone X , Price = 200 } "DDD" => Package { Id = 3 , Name = X7 Mouse , Price = 20 } Works as expected. Also, if you enter something that doesn't exist: "a" => Package { Id = 1000 , Name = Soda , Price = 1 } The Problem What if you need to add more coupon codes and return different variations of the Package object? Well, it's gonna get pretty messy very soon. Quick solution - Dictionary Rather than writing every possible variation in the if block, create a dictionary where the key is the coupon code and the value is the Package: private static readonly Dictionary < string , Package > _packages = new () { [ "ABC" ] = new Package { Id = 1 , Name = "PS5 Controller" , Price = 50.00 }, [ "EBC" ] = new Package { Id = 2 , Name = "Iphone X" , Price = 200.00 }, [ "DDD" ] = new Package { Id = 3 , Name = "X7 Mouse" , Price = 20.00 }, }; The next step is to