Search

Lessons (40)

• Dependencies, Data Sources, and Resource Lifecycle

  … Further reading: [Lifecycle reference](https://developer.hashicorp.com/terraform/language/meta-arguments/lifecycle), [data sources](https://developer.hashicorp …

• CQRS & Event Sourcing

  … you can use CQRS without event sourcing (very common), and event sourcing almost always needs CQRS for queries …

• Embeddings, Semantic Search, and RAG

  Use vector representations to retrieve relevant source material and ground language-model answers in your documents. The big …

• Developer Learning Plan and Document-Assistant Capstone

  … Ask it to answer from sources and abstain when evidence is insufficient. 5. Check responses: verify source identifiers …

• AWS Data Pipelines in Plain Language

  … Keep raw source data available under a deliberate retention policy. Transform into typed, validated records, and quarantine malformed …

• Batch vs Stream and Data Modeling

  Choose when work runs and shape data for correctness first, then deliberately denormalize proven read bottlenecks. The problem …

• Storage, Search and Location Queries

  … retry indexed events, compare source/index counts, and rebuild an index from source data after a mapping bug …

• Big Data: ETL, Warehouses and Streaming

  … They often expose hidden assumptions about mutable source data, schema changes and duplicate events.

• Caching, Consistent Hashing and Sharding

  Move reads close to users, distribute data safely, and understand cache and database consistency costs. The problem in …

• IAM Deep Dive: Policy Evaluation, STS and Cross-Account Access

  … Test with sample receipt data and a dedicated role; do not broaden to administrator access just to make …

• Cross-Service Data: How to Join Without a Database JOIN

  … Use an outbox in each source service so important events are not lost between the database commit and …

• Event-Driven Architecture

  … 2, "occurredAt": "2026-09-28T10:15:00Z", "source": "ordering-service", "correlationId": "req-7f3c", "data": { "orderId": "o42", "customerId": "c7 …

• Normalization & Denormalization

  … normalized source of truth can publish a controlled, rebuildable read model for a fast dashboard](/img/database/normalization …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … Set reserved concurrency or event source maximumConcurrency so a burst cannot overwhelm your database. AWS reference: [SQS event …

• System Design Interview Framework

  … 4. Model data and name each source of truth. 5. Define APIs with authorization and idempotency. 6. Deep …

• AWS Databases: Choose the Right One

  … read the source database and keep the app correct, while protecting it from excessive fallback traffic. Cleanup: for …

• Kafka vs RabbitMQ & the Kafka Ecosystem

  … code. - Source connectors pull data into Kafka: databases (Debezium CDC), S3, MQTT, Salesforce. - Sink connectors push data out …

• Secrets, Ephemeral Values, and Least Privilege

  … A plan often requires read access, but some providers or data sources need additional capabilities. Verify actual behavior …

• Choosing a Programming Language

  … Go, Rust"] S1[source] -- C1[compiler] -- B1[native binary] -- CPU1[CPU] end subgraph INT["Interpreted: Python"] S2[source …

• Drift, Troubleshooting, and Disaster Recovery

  … Reverting source code and applying it is a new infrastructure change. It may replace resources, lose data, or …

• Concurrency, Resilience & Distributed Workflows

  … CQRS and event sourcing are useful specialized patterns, not defaults; learn them in [Data in Microservices: Sagas & the …

• Serverless: Lambda and API Gateway

  … Do not use the module dictionary as a production database; execution environments can disappear or be replicated. Test …

• VPC Networking Without the Confusion

  … allow app port, source = ALB security group App → Database: allow 5432, source = App security group Using a security …

• What Is Apache Kafka?

  … live dashboards Data pipelines / CDC database changes → data warehouse Event sourcing the log IS the source of truth …

• Domain-Driven Design: Tactical Patterns

  … sourcing , see the Microservices lessons). Factories When creating an aggregate is complex (many rules, several sources of data …

• Clean Architecture in Depth

  … The control flow goes outward (use case → database), but the source-code dependency points inward (the Postgres adapter …

• C4 Architecture Diagrams: Context, Container, Component and Code

  … Label interfaces and boundaries, especially database, queue and external-service adapters. 5. Compare the diagram with the source …

• Advanced TypeScript for Frontend

  … true; data: T }; type ApiFailure = { ok: false; error: { code: string; message: string } }; type ApiResult<T = ApiSuccess<T ApiFailure …

• Putting AI Systems into Production

  … and monitoring Version prompts, model identifiers, retrieval configuration, source data, and evaluation sets. Before release, run regression tests …

• Prompting and Structured Outputs

  … source material or use retrieval. Do not ask it to “think harder” as a substitute for missing data …

• Safe AWS Deployments with IaC and CI/CD

  … Production data may need explicit retention policies and protection from stack deletion. An easy application pipeline For the …

• Architecture Patterns at Scale

  … Start with modules for catalog, checkout and fulfillment, with explicit interfaces and data ownership. 2. Extract a service …

• TypeScript in Practice

  … return ${state.data.length} users ; // data exists here ✅ case "error": return Failed: ${state.error} ; default: return assertNever(state …

• AI Evaluation, Safety, and Security

  Build representative tests, measure retrieval and model quality, defend against prompt injection, and handle sensitive data responsibly. The …

• AWS Messaging: Queues, Topics and Events

  … Still design safe retries. An EventBridge event json { "source": "academy.shop", "detail-type": "OrderPlaced", "detail": { "order id": "1001 …

• Transformers and Large Language Models

  … Models can produce plausible errors, reflect gaps or bias in training data, and struggle with ambiguous instructions or …

• Environments, Workspaces, and Multiple Accounts

  … dev may use a small database, while production enables replicas and deletion protection. Reuse the underlying module rather …

• Behavioral Patterns II: Chain, Template, Iterator, Mediator, Memento, Visitor

  … class DataImporter { // The template: fixed order of steps async run(source) { const raw = await this.read(source); const …

• Data Preparation and Model Training

  … Raw sources] -- C[Clean and validate] C -- L[Define labels and time window] L -- S[Split data] S …

• Terraform: Start Here

  … Example --- --- --- Resource Something Terraform manages An S3 bucket Data source A read of existing information An existing VPC …