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Ever looked at std::any and wondered what’s going on behind the scenes? Beneath the intimidating interface is a classic technique called type erasure: concrete types hidden behind a small, uniform wrapper. Starting from familiar tools like virtual functions and templates, we’ll build a minimal std::any . By the end, you’ll have a clear understanding of how type erasure works under the hood. submitted by /u/david-alvarez-rosa [link] [留言]

Hi everyone, I am Felix, a famliy doctor from ZH, Switzerland. A couple of month ago I started this little project called shii • haa, a breathing app that uses the phone`s microphone for live biofeedback My prior work in emergency medicine and intensive care was closesly linked to breathing, mostly in critical situations... and let me to reevaluate my own way of breathing. over time one question popped into my mind: can medical knowledge and biofeedback make an app actually promote self-awarenes

Nintendo's music app works in a lot more places now.

Ableton already has Max for Live, which allows users to build MIDI effects, synths, and samplers for its digital audio workstation (DAW). But now with its Extensions SDK, features can be added to Ableton Live with common JavaScript. Where Max is largely limited to MIDI and audio processing, Extensions can touch almost any part of […]

T-SQL on Microsoft Fabric - Episode 1: Mastering Data Retrieval with SELECT, WHERE, and ORDER BY Learning Goals In this lesson, you will learn how to: Read data from tables using SELECT Filter rows with WHERE Sort query results with ORDER BY Get familiar with standard T-SQL syntax Practice directly in Microsoft Fabric Warehouse 1. Understanding Database and Schema In Fabric Warehouse, objects are commonly organized like this: Warehouse | |-- sales | |-- Customers | |-- Orders | |-- hr | |-- Employees | |-- finance |-- Transactions Schemas help you: Group related tables Manage permissions Organize large systems more effectively 2. Create a Schema Create a schema for the sales dataset: CREATE SCHEMA sales ; Check existing schemas: SELECT * FROM sys . schemas ; 3. Create Tables Create the Customers table: CREATE TABLE sales . Customers ( CustomerID INT , CustomerName VARCHAR ( 100 ), City VARCHAR ( 50 ), Country VARCHAR ( 50 ) ); Create the Orders table: CREATE TABLE sales . Orders ( OrderID INT , CustomerID INT , OrderDate DATE , Amount DECIMAL ( 10 , 2 ) ); 4. Insert Sample Data Customers INSERT INTO sales . Customers VALUES ( 1 , 'John Smith' , 'New York' , 'USA' ), ( 2 , 'Emma Brown' , 'Chicago' , 'USA' ), ( 3 , 'David Wilson' , 'London' , 'UK' ), ( 4 , 'Sophia Taylor' , 'Manchester' , 'UK' ), ( 5 , 'Michael Lee' , 'Singapore' , 'Singapore' ); Orders INSERT INTO sales . Orders VALUES ( 101 , 1 , '2026-01-10' , 1200 . 00 ), ( 102 , 1 , '2026-01-15' , 800 . 00 ), ( 103 , 2 , '2026-01-20' , 2500 . 00 ), ( 104 , 3 , '2026-02-01' , 500 . 00 ), ( 105 , 5 , '2026-02-05' , 3200 . 00 ); 5. SELECT Get all columns: SELECT * FROM sales . Customers ; Get specific columns: SELECT CustomerName , Country FROM sales . Customers ; 6. Alias Rename columns in the output: SELECT CustomerName AS Customer , Country AS Nation FROM sales . Customers ; 7. WHERE Filter rows using conditions. Customers in the USA: SELECT * FROM sales . Customers WHERE Country = 'USA' ; Orders greater than 100

Your API is fast. Your code is clean. Your architecture looks solid on paper. Then you hit 500,000 records and everything slows down. Queries that ran in 12ms now take 4 seconds. Your dashboards lag. Users start filing support tickets. Your on-call engineer is staring at a query plan at midnight wondering what went wrong. Nine times out of ten, the answer is indexing. Not missing indexes — wrong indexes. Indexes that exist but don't help. Indexes that actively hurt write performance without meaningfully improving reads. This is a breakdown of the most damaging database indexing mistakes in production SaaS systems — and how to fix them before they become incidents. Mistake 1: Indexing Everything "Just in Case" The most common mistake isn't under-indexing. It's over-indexing out of anxiety. New engineers especially fall into this pattern — add an index on every column that appears in a WHERE clause, just to be safe. Seems responsible. It isn't. Every index you add is a write tax. On every INSERT, UPDATE, and DELETE, PostgreSQL (or MySQL) has to update every index on that table. On a table with 8 indexes, every write touches 8 data structures. At low volume, this is invisible. At 10,000 writes per minute, it becomes your bottleneck. The fix: Audit your indexes regularly. In PostgreSQL: SELECT schemaname , tablename , indexname , idx_scan , idx_tup_read , idx_tup_fetch FROM pg_stat_user_indexes ORDER BY idx_scan ASC ; Any index with idx_scan = 0 or near zero hasn't been used since your last stats reset. That's a candidate for removal — not immediately, but after investigation. Mistake 2: Not Understanding Index Selectivity An index on a boolean column ( is_active , is_deleted ) is almost always useless. Here's why: selectivity measures how many distinct values exist relative to total rows. A boolean column has two values. If 95% of your rows have is_active = true , an index on that column tells the query planner almost nothing useful. It will often skip the index entire

submitted by /u/NoPercentage6144 [link] [留言]

When most people think about Java, they immediately picture enterprise applications, banking systems, massive backend services, or decades-old corporate software. While Java has earned its reputation in the enterprise world, that is only part of the story. Today, Java can run on devices as small as a Raspberry Pi, opening the door to hardware projects, edge computing, home automation, education, and hands-on learning experiences. Combining Java with Raspberry Pi creates a powerful platform for experimentation, learning, and building real-world solutions that go far beyond traditional enterprise development. Raspberry Pi teaches us about hardware. Java allows us to apply professional software engineering practices to that hardware. Together, they create a powerful platform for learning, prototyping, and building real-world IoT and edge computing solutions. Java Is More Than Enterprise Software Java's enterprise success has sometimes created the misconception that it only belongs in large organizations. In reality, modern Java offers: Excellent support for Linux and ARM architectures. High performance and low resource consumption. Modern frameworks such as Spring Boot, Quarkus, and Micronaut. Strong support for IoT and edge computing. Access to hardware through mature libraries. One of the largest developer ecosystems in the world. The Raspberry Pi highlights a different side of Java—one focused on creativity, experimentation, and direct interaction with the physical world. Instead of building another web application, you can build systems that sense, react, and interact with their environment. Java at the Edge One of the most exciting technology trends today is Edge Computing. Traditionally, devices send data to cloud services where processing and decision-making occur. Edge computing shifts part of that processing closer to where the data is generated. A Raspberry Pi running Java can: Process sensor data locally. Apply business rules before sending information to th

"The propellant farm, oxygen, liquid hydrogen, and LNG tanks are all in good shape."

X will now let you 'react with video' to posts.

submitted by /u/goto-con [link] [留言]