Search the practice set
275 questions, 991 terms and 600 topics in 30 areas.
60 results for “Client Caching & Data Layer”
Stale While Revalidate
Serving cached data immediately while fetching a fresh copy in the background, which makes an interface feel instant at the cost of a brief inconsistency.
Client-Specific Aggregation
A dedicated backend per client type that shapes and combines downstream data for that client's needs, owned by the client team.
Airbnb's Service-Oriented Migration
Airbnb decomposed a large Rails monolith by first extracting a unified data-access layer, so that services were built on owned data rather than on shared database tables.
Cache Invalidation
The problem of removing or refreshing cached data when the underlying source changes, and the reason caching is harder than it looks.
Connection Proxy
A pooling layer between applications and a managed database that multiplexes many client connections onto a small number of database connections.
Figma's Postgres Sharding
Figma delayed sharding for years using replicas and vertical partitioning, then sharded Postgres horizontally without downtime using logical shards and a proxy layer.
Layered Architecture
Organising code into horizontal layers — presentation, application, domain, data — where each layer may only call the one beneath it.
Netflix's Recommendation Architecture
Netflix splits personalisation into offline, nearline and online layers so that expensive computation happens ahead of time and the request path stays fast.
Open Table Format
A metadata layer over files in object storage that supplies ACID transactions, schema evolution and time travel — the thing that turns a data lake into a lakehouse.
Origin Shield
An intermediate caching layer between CDN edge nodes and the origin, so a cache miss at many edges results in one origin request rather than many.
Read Timeout
The bound on how long a client waits for response data after a connection is established — distinct from the connect timeout, and the one that usually matters.
Server State Versus UI State
The distinction between data owned elsewhere and cached locally, and state that exists only in this session — conflating them causes most client state bugs.
Anti-Corruption Layer
A translation layer that converts a legacy or external system's model into your own, so its concepts do not leak into your domain.
Bronze Layer Contract
What the raw landing zone promises and refuses to promise — a faithful replayable copy of the source, with no correction applied.
Caching Strategy
The chosen pattern for how a cache is populated, read and invalidated — cache-aside, read-through, write-through or write-behind.
Capital One's Data Centre Exit
A major US bank closed all eight of its data centres and moved fully to public cloud, treating governance automation as the enabling technology rather than a constraint.
Change Data Capture
Publishing a stream of a database's row-level changes by reading its replication log, without modifying the application that owns it.
Client Runtime Constraint
The properties of the browser or device you do not control — CPU, network, version, extensions — which make the client a distributed system component rather than a rendering surface.
Client-Side Discovery
The caller queries the registry itself and chooses an instance, rather than sending to a stable address that something else resolves.
Control Plane and Data Plane
The separation between the machinery that makes changes to a system and the machinery that serves its traffic.
Cross-Zone Data Transfer
Charges incurred when data moves between availability zones within a region — invisible on architecture diagrams and a recurring surprise on cloud bills.
Data Catalog
A searchable inventory of datasets with their schema, owner, meaning, freshness, quality and classification.
Data Contract
An explicit, versioned, enforced agreement between a data producer and its consumers about schema, semantics, quality and change policy.
Data Discovery
Automatically scanning stores to find where sensitive data actually resides, as distinct from where the documentation says it should.
A regulated client requires that no traffic between their data centre and your SaaS platform traverses the public internet. Design the connectivity and justify the cost.
Two distinct requirements hiding in one sentence Traffic must not traverse the public internet — a routing requirement. The client must be able to demonstrate i
A product catalogue page does 40,000 reads per second against a database that can serve 5,000. Walk me through the caching design, including what happens at 3 AM when the cache is empty.
What the interviewer is testing Whether you can design a cache including its failure modes, rather than saying "put Redis in front of it". The base design Cache
Finance and Sales report different revenue for the same quarter. Both are convinced they are right. You are asked to fix the data. Where do you start?
Assume neither number is wrong The instinct is to look for a bug. In practice the overwhelming majority of these cases are two defensible definitions with no me
A CDO proposes moving to a data mesh because the central data team is a bottleneck with a nine-month backlog. How do you assess the proposal?
Agree with the diagnosis, examine the prescription The bottleneck is real and it is structural rather than a matter of capacity. A central team receives data fr
A GDPR erasure request arrives for a customer. Where does their data actually live, and what makes this expensive to retrofit?
Where the data lives Longer than people expect, and enumerating it is most of the work: Primary database · read replicas · caches · search indexes · analytical
A business sponsor asks for a real-time data platform because "the competition has one". Reporting is currently a nightly batch that lands at 06:00 and nobody has complained. How do you handle this?
Do not answer the technology question "Real time platform" is a solution, and it has arrived without a problem attached. Answering it directly leads either to a
A client wants an assistant that answers questions from 50,000 internal documents which change weekly. RAG or fine-tuning? What actually determines the quality?
What the interviewer is testing Whether you understand what each technique actually does, and whether you know that RAG quality is a retrieval problem. Why RAG
A marketing site is a client-rendered single-page application. Organic traffic is poor and the team blames the search engine. What is your assessment?
The rendering choice is the problem A marketing page is identical for every visitor and highly cacheable. Rendering it in the browser pays for personalisation t
A new platform must serve a public partner API, three internal front-ends with different data needs, and high-volume service-to-service traffic. Choose the API styles and defend the choice.
Resist "pick one" These are three different problems with three different consumers. Standardising on one style optimises for architectural tidiness at the expe
A query that ran in 50ms for two years now takes 90 seconds. Nothing was deployed and the data volume grew normally. What happened?
The most likely cause: a plan flip The optimiser's choice is a function of estimated row counts. As the data grows or its distribution shifts, an estimate cross
A regulator asks whether customer data is encrypted. The team says yes, disks are encrypted. Is that a sufficient answer?
What disk encryption actually protects against Someone obtaining the physical medium or a raw storage snapshot. In a cloud context that means a provider employe
A service becomes unresponsive during an incident in a dependency it barely uses. Investigation finds the client had no read timeout. Explain the full mechanism.
The mechanism, step by step 1. The dependency slows. It has not failed — it accepts connections and eventually responds, just very slowly. This is the important
Choose storage for four workloads: a Postgres data directory, user-uploaded images, a shared build cache, and seven years of audit records.
Postgres data directory — block storage It needs low latency random reads and writes and a filesystem, and it attaches to one instance. That is precisely block
Client Caching & Data Layer
Stale-while-revalidate, invalidation and optimistic updates on the client.
Caching Strategies
Cache-aside, read-through, write-through and where each belongs.
Caching for Performance
Layer choice, hit ratio as a first-class metric, and cold-cache recovery.
Real-Time Serving Layer
Where a low-latency read of a streaming aggregate actually lands.
Semantic Layer
Metric definitions held once and served to every tool that asks.
Medallion Architecture
Bronze, silver and gold layers, and what each layer is allowed to guarantee.
Anti-Corruption Layer
Translating a foreign model at the boundary so it does not leak in.
Change Data Capture
Turning a database's replication log into a stream, and its coupling risk.
Client Feature Flags
Flag evaluation on a device you do not control, and the flicker and staleness it brings.
Client State Architecture
Server state, UI state and derived state, and why conflating them causes most bugs.
Data Access Models
Role, attribute and purpose-based access over analytical data, and how they compose.
Data Architecture
General material on structuring, storing and governing data.
Data Catalog
Discovery, ownership and technical metadata, and why catalogues go stale.
Data Classification
Knowing which fields are regulated, because every control depends on it.
Data Contracts
Producers committing to schema, semantics and freshness, and breaking builds when they do not.
Data Governance
Ownership, lineage, quality, catalogues and who may see what.
Data Governance & Semantics
General material on ownership, meaning, quality and control of data at enterprise scale.