Answer: no. Exactly day 7 means exactly, so day 6 and day 8 count for nothing. Join on activity_day = signup_date + 7, not a range, and the equality enforces "exactly" for free.
Quick SQL quiz.
A user signs up, comes back on day 6, then on day 8.
Day-7 retained: yes or no?
Answer in the replies. Try it first, free:
leetdata.ai/problems/day-n-r…
#dataengineering #sql
For engineers in India switching into data engineering:
All 200 leetdata.ai problems are free. SQL, Python, PySpark, hints, editorials. Plus 1 AI mock interview in week 1.
Practice for the rounds DSA prep skips.
leetdata.ai/problems
#dataengineering #sql
Good timing on that one. Support for the Azure Functions in-process model ends Nov 10, 2026, so the isolated worker move is the part that can't wait.
Ratings: 4.9, 4.8, 4.7, 4.7, 4.5
ROW_NUMBER: 1 2 3 4 5
RANK: 1 2 3 3 5
DENSE_RANK: 1 2 3 3 4
Ask for a "top 3" with RANK and you get 4 rows.
Top N per Group, free on leetdata.ai:
leetdata.ai/problems/top-n-p…
#dataengineering #sql
Replying to @sammiyoung01
Good pick. The Data Pipelines track on leetdata.ai opens with DAGs, sensors and idempotency, then has you debug real incidents like stuck sensors and retry storms. The beginner levels are free: leetdata.ai/paths/pipeline Airflow or Dagster first?
Want daily data engineering breakdowns, system architectures, and paper teardowns sent directly to your phone?
Join our new Data Engineering Weekly WhatsApp Channel! 🚀
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Key Highlights from Affirm’s ML & Decision Platform team:
• Separation of Concerns:Core transaction flows invoke the Intelligence Layer asynchronously or via tight SLA RPCs.
• Online/Offline Consistency: Unified feature tables bridge batch analytics and real-time decisioning.
Affirm processes billions in credit risk and checkout workflows every day.
How do they handle real-time ML inference without crashing checkout latency?
They built an isolated "Intelligence Layer." 🧵👇
💡 Key Takeaway:
GPU-accelerated analytics on Mac hardware is becoming plug-and-play. Registering physical optimizer rules allows high-performance Rust data frameworks like DataFusion to unlock massive speed gains effortlessly.
🛡️ Smart Guardrails:
The rule evaluates warm/idle GPU costs and hand-back cases (e.g., complex float NaNs or streaming Top-K queries where CPU is better).
If conditions aren't optimal or memory limits trigger, it seamlessly falls back to standard CPU execution.
🧠 Zero-Copy Architecture:
Because Apple Silicon uses unified memory, Apache Arrow buffers are read directly in place by the GPU.
No expensive data copying back and forth between CPU and GPU memory.
⚡ How it works:
The ArrowMetal rule (datafusion-arrowmetal Rust crate) intercepts execution plans in DataFusion's SessionContext.
When registered, EXPLAIN shows a MetalExec node in place of SortExec. The exact same SQL query runs on the Metal GPU pipeline!
🚀 Apache DataFusion can now leverage Apple Silicon GPUs for massive query speedups!
By registering a single optimizer rule via ArrowMetal, full SQL sorts run 6.9x to 28.8x faster on Apple Silicon—without changing a single line of SQL. 🧵👇
dataengineeringweekly.com/i/…
8 SQL problems. About 20 minutes end to end.
leetdata.ai's "Start here" set: the SQL a DE interviewer opens with. CASE WHEN order, BETWEEN bounds, blank vs NULL, a first CTE.
Easy on purpose. Screens slip here.
leetdata.ai/problems
#dataengineering #sql
Thanks for the correction, and for a great write-up from @avrahamr and Roy Noyman. Wix it is, noted for next time.
Replying to @sammiyoung01
Welcome, Samuel! A solid first step: the 8 "Start here" SQL problems on leetdata.ai take about 20 minutes and cover what DE interviewers open with. Which side are you leaning toward, pipelines or analytics?
👉 Practice for free now: leetdata.ai
#DataEngineering #SQL #PySpark #Career #TechInterviews #LeetData

