---
title: "Latest reads"
description: "The engineering internet, summarised so you can actually read it."
---

# Latest reads
> The engineering internet, summarised so you can actually read it.

## Articles

### [Postgres as a CRON Server](https://yomu.fyi/post/postgres-as-a-cron-server.md)
- Company: [Supabase](https://yomu.fyi/company/supabase.md)
- Author: Paul Copplestone
- Published: Mar 5, 2021
- Type: Tutorial

Postgres databases can schedule and execute external webhook calls periodically by combining the pg\_cron and pgsql-http extensions. When configured, pg\_cron schedules recurring tasks using standard cron syntax directly inside the database engine. In conjunction, the pgsql-http extension dispatches HTTP requests such as GET, POST, PATCH, and DELETE to external endpoints within SQL queries. Because pg\_cron relies on background workers that start one process per server loop iteration, scheduled jobs do not interfere with core postmaster tasks or external client connections. Administrators can monitor job status, review execution logs, and unschedule active tasks directly through dedicated cron schema tables and helper functions.


### [Supabase Beta February 2021](https://yomu.fyi/post/supabase-beta-february-2021.md)
- Company: [Supabase](https://yomu.fyi/company/supabase.md)
- Author: Paul Copplestone
- Published: Mar 2, 2021
- Type: Announcement

Supabase published its February 2021 beta update marking one year of development as an open-source Firebase alternative. The release introduces dashboard interface improvements across the Table view, Auth section, and SQL Editor, which now features autocomplete suggestions for tables and columns. Authentication updates allow user redirection to specific site routes upon invoking signIn and signUp, while a new database management interface lets users configure Postgres replication settings and events for the realtime API. Infrastructure additions include a new deployment region in South Africa and a Docker Compose configuration intended to power local development in the forthcoming CLI. Documentation expanded with resources for GoTrue and Google OAuth, alongside ongoing RFCs covering connection pooling and local workflows.


### [4 Tips for Shipping Data Products Fast](https://yomu.fyi/post/4-tips-for-shipping-data-products-fast.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Mar 2, 2021
- Type: Explainer

Shipping data products under tight deadlines requires teams to stay focused while avoiding overengineering and building something users will not use. Shopify’s Data Science team recommends four practices: run a timeboxed design sprint with a small team and a designated Champion, prototype quickly—often with spreadsheets—and gather feedback throughout development. For first iterations, the post advises using simple approaches instead of machine learning when complexity would delay integration, polish, and user conversations; a sales forecasting prototype used linear regression with two input variables before a more complex model was built. User research should use specific questions and a diverse set of users, as feedback changed a confusing 0–100 scoring display to easier-to-interpret letter grades. Together, these practices provide a clearer path to launching useful products quickly.


### [SSH and User-mode IP WireGuard](https://yomu.fyi/post/ssh-and-user-mode-ip-wireguard.md)
- Company: [Fly.io](https://yomu.fyi/company/fly-io.md)
- Published: Mar 1, 2021
- Type: Explainer

Fly.io’s SSH feature addresses the need to access applications running in Firecracker micro-VMs without requiring users to build containers with an SSH service or install WireGuard. The first part uses 6PN, a private IPv6-based network routed across Fly’s WireGuard mesh, and Hallpass, a small Go SSH server bound to each instance’s 6PN address. Authentication relies on an organization’s root SSH certificate published in private DNS, while the API signs short-lived user certificates. To support users without WireGuard installed, flyctl combines wireguard-go’s userland protocol with gVisor’s user-mode TCP/IP stack, allowing ordinary Go networking code and DNS resolution to operate over the private network. The resulting certificate-based SSH path is built into flyctl and reaches internal DNS names such as dogmatic-potato-342.internal, although the user-mode implementation is substantially slower than kernel TCP/IP.


### [Cracking PostgreSQL Interview Questions](https://yomu.fyi/post/cracking-postgresql-interview-questions.md)
- Company: [Supabase](https://yomu.fyi/company/supabase.md)
- Author: Ant Wilson
- Published: Feb 27, 2021
- Type: Tutorial

The guide prepares candidates for PostgreSQL interviews by concentrating on transactional SQL rather than mixing it with analytical topics such as window functions, ranking, and aggregates. It covers relational modeling with foreign keys and join tables, PostgreSQL’s richer types, schemas, indexing strategies, and EXPLAIN ANALYZE for comparing estimated and actual query costs. It also addresses views, automatically updatable views and their limitations, database permissions, roles, PUBLIC grants, row-level security policies, and business logic implemented with PL/pgSQL functions and triggers. The guide recommends thinking in sets with SQL operations such as JOIN and UNION, using common table expressions for readable or recursive queries, and practicing these topics to build a strong foundation for PostgreSQL interview answers.


### [Simple considerations for simple people building fancy neural networks](https://yomu.fyi/post/simple-considerations-for-simple-people-building-fancy-neural-networks.md)
- Company: [Hugging Face](https://yomu.fyi/company/hugging-face.md)
- Author: Victor Sanh
- Published: Feb 25, 2021
- Type: Explainer

Building and training neural networks often presents frustrating debugging challenges because implementations can contain subtle errors while still running without crashes and achieving decent performance. The author shares a mental framework derived from natural language processing research to systematically construct and debug deep learning workflows. Practitioners should begin with thorough qualitative and quantitative dataset analysis before implementing simple baseline models to establish performance benchmarks. When coding the network, developers should verify implementation correctness by overfitting a tiny batch without regularization and tracking training dynamics such as losses, parameters, and gradients. Hyperparameter optimization should prioritize understanding underlying component behaviors through targeted random grid searches rather than launching hundreds of blind runs.


### [Keeping Developers Happy with a Fast CI](https://yomu.fyi/post/keeping-developers-happy-with-a-fast-ci.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Feb 24, 2021
- Type: Problem & solution

Shopify’s Test Infrastructure team tackled a 45-minute 95th-percentile CI time for its Core monolith, which had more than 170,000 tests and ran on every git push. They instrumented Buildkite commands and prioritized agent preparation, dependency building, and test execution using command frequency and duration. Disk I/O from writing large caches slowed Docker startup, so the team increased disk capacity and write speed, mounted most caches read-only, skipped unchanged database and asset work through hashes, parallelized setup, and expanded changed-file test mappings. These changes reduced container-start p95 from 90 to 25 seconds, raised builds avoiding the full suite from 45% to over 60%, improved test stability from 88% to 97%, and lowered overall CI p95 to 18 minutes.


### [One Small Step Closer to Containerising Service Binaries](https://yomu.fyi/post/one-small-step-closer-to-containerising-service-binaries.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Stan Halka
- Published: Feb 23, 2021
- Type: Problem & solution

Engineering teams at Grab initiated a transition to containerized microservices to standardize environments, enhance security, and decouple services from internal runtime tooling. During this migration, developers noticed that statically-linked Go service binaries were reaching bloated sizes over 100 MB. By analyzing the binaries using the open-source tool go-binsize-viz alongside the Go nm toolchain, the team visualized compiled symbols as interactive treemaps. This analysis revealed that 11 MB of unused message format symbols were being pulled in because a generic interface shared a directory with auto-generated streaming code. Restructuring the packages to isolate interfaces from generated code successfully decreased the binary size down to 78 MB.


### [Read Consistency with Database Replicas](https://yomu.fyi/post/read-consistency-with-database-replicas.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Feb 22, 2021
- Type: Explainer

Database replicas can improve read-heavy application performance and reduce pressure on primary servers, but differing replication lag can make multi-query reads produce incoherent datasets. Shopify’s Database Connection Management team compared tight consistency and GTID-based causal consistency before choosing opt-in monotonic read consistency, in which related reads are routed to one replica and therefore follow a consistent timeline rather than necessarily seeing the latest data. Their ProxySQL fork accepts a UUID in the consistent\_read\_id query comment, hashes it into a pseudorandom index over a weighted hostgroup server list, and disables later rebalancing that could override the selection. The implementation indexes configured servers before handling outages, though a selected server failure can still break consistency. The approach offers low overhead but tolerates occasional inconsistencies.


### [Bound to Round: 8 Tips for Dealing with Hanging Pennies](https://yomu.fyi/post/bound-to-round-8-tips-for-dealing-with-hanging-pennies.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Feb 16, 2021
- Type: Problem & solution

Financial software must round values when money cannot be transacted beyond two decimal places, creating precision loss and “hanging pennies.” The post demonstrates that rounding two percentage-based charges separately on $10.10 produces $0.53, while summing the unrounded amounts and rounding once produces $0.54; currency conversions can amplify the effect. Its eight recommendations include notifying stakeholders, using banker’s rounding, retaining maximum available precision in data types, applying one consistent method, marking rounding explicitly, consulting government standards, rounding only when required, and documenting rules for users. It identifies taxes, discounts, interest, distributed payments, shared liabilities, and rates as recurring sources of rational values in financial calculations. The conclusion is that rounding cannot be avoided in financial software, but teams can control where it occurs and how its consequences are handled.


### [Persistent Storage and Fast Remote Builds](https://yomu.fyi/post/persistent-storage-and-fast-remote-builds.md)
- Company: [Fly.io](https://yomu.fyi/company/fly-io.md)
- Published: Feb 15, 2021
- Type: Announcement

Fly introduces persistent volumes for apps and a new remote-build path designed to make Docker image builds faster. Volumes are created through flyctl, backed by encrypted ext4 filesystems on Linux LVM2 thin pools, and attached one-to-one with app instances on compatible hosts. Volumes survive reboots and deployments and are described as performance-competitive with, usually slightly faster than, EBS, but raw-volume resilience remains the customer’s responsibility. Because volume count limits instance count and prevents an extra canary volume, volume-backed apps use rolling deployments; the post identifies replicated database clusters, caches, metrics, and restorable data as suitable cases. Remote builds now match jobs to automatically created builder apps with attached storage for cached layers and manifests; builders expose authenticated Docker servers, terminate after 10 minutes of inactivity, and are not restarted after successful exit.


### [The Tokio Upgrade from 0.2 to 1.x](https://yomu.fyi/post/the-tokio-upgrade-from-0-2-to-1-x.md)
- Company: [Fly.io](https://yomu.fyi/company/fly-io.md)
- Published: Feb 12, 2021
- Type: Tutorial

Fly.io’s Rust-based load balancer handles almost all of its traffic and stands on Tokio and Hyper, motivating an upgrade from Tokio 0.2 to 1.0. The team waited to upgrade until related crates including hyper, reqwest, async-compression, tokio-io-timeout, tokio-tungstenite, and sentry were ready; after a few weeks, most of the ecosystem had upgraded. The migration foregoes Tokio’s Stream implementations pending stabilization in the standard library, relaxes mutable-access requirements, changes AsyncRead and AsyncWrite polling to return Result<()>, and requires more explicit pinning for !Unpin futures. Because runtime::Handle lacked block\_on, the team worked around the restriction with Arc; standard TcpListener values also required set\_nonblocking(true) before TcpListener::from\_std. Other changes included renamed APIs and revised Hyper WebSocket upgrades, and the author says the major upgrade was not hard.


### [Using Betas to Deploy New Features Safely](https://yomu.fyi/post/using-betas-to-deploy-new-features-safely.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Feb 12, 2021
- Type: Explainer

Continuous deployment makes changing a running system risky, especially for a platform serving more than a million merchants and changing code multiple times daily. The post presents beta flags as a control mechanism: per-Subject BetaFlags support explicit activation, while BetaRollouts use a percentage and a digest-based modulo calculation to assign a stable, growing subset as rollout increases. It then places a higher-level Feature abstraction above those primitives, allowing direct targeting, percentage rollout, per-Subject opt-outs, and a 100% kill switch that can halt a feature without deleting thousands of database records. The guidance also covers testing permutations, notifying owners through BetaIdentifier metadata, and removing stale flags after rollout. These patterns provide operational control and safer deployment, while requiring substantial implementation and ongoing cleanup.


### [Technical Mentorship Reimagined: Time-bound and No Awkward Asks Necessary](https://yomu.fyi/post/technical-mentorship-reimagined-time-bound-and-no-awkward-asks-necessa.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Feb 10, 2021
- Type: Explainer

Shopify’s Engineering Mentorship Program was created to give developers a structured way to pursue technical and leadership growth alongside the company’s existing just-in-time collaboration. Survey findings indicated that developers wanted to learn from colleagues but struggled to make dedicated time, motivating a recurring program designed around those constraints. Each six-week cycle uses voluntary sign-up, automated matching based on expertise, reporting relationships, and job level, weekly one-hour meetings, goal setting, Slack support, and an optional guidebook. The time-bound format lets participants try a mentorship relationship without an open-ended commitment, while mentors also practice teaching and leadership; by 2020, more than 300 developers had participated as mentees and more than 200 as mentors, 98% of survey respondents said they would recommend it, and demand exceeded available mentor capacity.


### [Retrieval Augmented Generation with Huggingface Transformers and Ray](https://yomu.fyi/post/retrieval-augmented-generation-with-huggingface-transformers-and-ray.md)
- Company: [Hugging Face](https://yomu.fyi/company/hugging-face.md)
- Author: system
- Published: Feb 10, 2021
- Type: Problem & solution

Huggingface Transformers added the Retrieval Augmented Generation architecture to combine standard sequence-to-sequence models with external document retrieval for knowledge-intensive tasks. Scaling RAG fine-tuning across multiple GPUs previously created bottlenecks because the torch.distributed implementation forced the single rank 0 worker to handle all retrieval index lookups. To resolve this synchronization bottleneck, Ray was integrated into the contextual document retrieval mechanism using stateful actor abstractions. Dedicated Ray processes separate from the training workers now load the large index and process retrieval requests concurrently. This architectural separation delivers up to a 2x speedup per retrieval call and removes the strict dependency on PyTorch for training.


### [Roboflow.com choose Supabase to power Paint.wtf leaderboard](https://yomu.fyi/post/roboflow-com-choose-supabase-to-power-paint-wtf-leaderboard.md)
- Company: [Supabase](https://yomu.fyi/company/supabase.md)
- Author: Rory Wilding
- Published: Feb 9, 2021
- Type: Problem & solution

Brad Dwyer and Erik Dunteman created Paint.wtf to experiment with OpenAI's CLIP model, allowing users to draw images evaluated against text prompts and scored on a leaderboard. While the team initially considered Firebase, the platform lacked built-in document counting functionality essential for their leaderboard architecture. To avoid implementing custom workarounds or exporting data to external systems, they selected Supabase to leverage PostgreSQL's native counting capabilities. After launching on Hacker News, Reddit, and Product Hunt, the platform experienced viral traffic that peaked at over two drawing submissions per second and surpassed one hundred thousand participating users within twenty-four hours. The PostgreSQL-backed infrastructure maintained reliable performance throughout the surge, delivering accurate and up-to-date score rankings under heavy load.


### [Hugging Face on PyTorch / XLA TPUs](https://yomu.fyi/post/hugging-face-on-pytorch-xla-tpus.md)
- Company: [Hugging Face](https://yomu.fyi/company/hugging-face.md)
- Author: ds, Lysandre
- Published: Feb 9, 2021
- Type: Announcement

PyTorch / XLA integrates Cloud TPU training into Hugging Face transformers while preserving the standard Trainer interface. The implementation adds an xla device type and uses lazy execution to trace intermediate representation graphs before lowering them to XLA Higher Level Operations for compilation. Parallel data loading through MpDeviceLoader overlaps CPU tracing with TPU execution, while xm.optimizer\_step coordinates gradient consolidation across data-parallel replicas. Checkpoints use xm.save to transfer tensors via CPU storage and restrict disk writes to the master process. Benchmarks on a Cloud TPU v3-8 system training bert-large-uncased on WikiText-103 demonstrate completion times of 178.4 minutes in FP32 precision and 106.4 minutes in BF16 precision.


### [Customer Support Workforce Routing](https://yomu.fyi/post/customer-support-workforce-routing.md)
- Company: [Grab](https://yomu.fyi/company/grab.md)
- Author: Suman Anand
- Published: Feb 5, 2021
- Type: Problem & solution

Grab replaced its third-party customer support routing software with an in-house workforce routing system for Livechat to gain better priority controls, bespoke configurations, and deeper analytics. The platform separates requests into distinct priority and business queues, using parallel workers that spend varied time slices dequeuing higher-priority issues like safety concerns. To prevent request starvation, workers operate out of sync across queue priority levels while dynamic queue limits cap incoming volume based on agent availability and performance. The system routes requests through an intermediate Agent Group layer, calculating eligibility scores from proficiency and concurrency metrics while managing per-agent locks to prevent over-allocation.


### [You should know about Server-Side Request Forgery](https://yomu.fyi/post/you-should-know-about-server-side-request-forgery.md)
- Company: [Fly.io](https://yomu.fyi/company/fly-io.md)
- Published: Feb 5, 2021
- Type: Tutorial

Server-side request forgery (SSRF) lets attackers make an application server issue HTTP requests, potentially reaching internal resources behind its security perimeter and taking over the hosting environment. The post describes two common patterns—user-supplied URLs and user data incorporated into URLs—and presents Smokescreen, an egress proxy, as a mitigation. Smokescreen checks that requested IP addresses are publicly routed, blocking private IPv4 ranges and IPv6 ULA space, while ACL actions can open, report, or enforce traffic rules. The Fly modification authenticates clients with a shared PROXY\_PASSWORD, maps authenticated requests to an authed role, and includes deployment instructions for Fly and Docker plus Go and Node.js examples that send authenticated HTTPS requests through the proxy.


### [Supabase Beta January 2021](https://yomu.fyi/post/supabase-beta-january-2021.md)
- Company: [Supabase](https://yomu.fyi/company/supabase.md)
- Author: Paul Copplestone
- Published: Feb 2, 2021
- Type: Announcement

Supabase released a collection of platform updates during January 2021 covering database tools, authentication integrations, regional availability, and infrastructure performance. Client libraries added support for PostgREST exact, planned, and estimated count queries to eliminate counting friction commonly experienced in platforms like Firebase. Authentication capabilities expanded to include Facebook and Azure login providers, an in-dashboard GoTrue audit trail, a helper function for user emails, and a prebuilt React Auth Widget. The platform also enabled new database hosting regions in London and Sydney while transitioning storage to GP3 for improved throughput. Furthermore, migrating API subdomains to Route53 alongside custom Let's Encrypt certificates yielded read performance benchmark gains of up to twelve percent.


[Newer posts](https://yomu.fyi/posts/page/224.md) · [Older posts](https://yomu.fyi/posts/page/226.md)