Search the practice set
275 questions, 991 terms and 600 topics in 30 areas.
46 results for “Storage Layout & Partitioning”
Partition Pruning
The query planner skipping files whose partition values cannot satisfy the predicate, which is the single largest determinant of analytical query cost.
Block Storage
A virtual disk attached to one instance at a time, presented as raw blocks and formatted with a filesystem — the storage databases and stateful workloads run on.
Cumulative Layout Shift
The extent to which visible content moves unexpectedly during load, which correlates with mis-taps and is almost entirely preventable by reserving space.
Object Storage
Flat, HTTP-addressable storage for immutable blobs with rich metadata — effectively unlimited, cheap, and not a filesystem.
Storage Lifecycle Policy
Automated rules that move objects between storage classes as they age, matching cost to the declining probability that data will be read.
Storage Tiering
Moving data between access tiers as it cools, so rarely-read data is not paying hot-storage prices.
Bloom Filter
A compact probabilistic structure that answers "is this key definitely absent, or possibly present?" — no false negatives, tunable false positives.
Bulkhead
Partitioning resources so that exhaustion caused by one dependency or tenant cannot starve the others.
Cell-Based Architecture
Partitioning a service into complete, independent copies of itself, each serving a subset of customers, so a failure is bounded to one cell.
Consistent Hashing
A hashing scheme where adding or removing a node remaps only a small fraction of keys, instead of nearly all of them.
Data Lakehouse
A pattern that puts warehouse-style transactions, schema and governance on top of cheap open-format object storage.
Database Index
A secondary structure that lets the engine find rows without scanning, trading write cost and storage for read speed.
Dropbox's Move Off S3
Dropbox moved the majority of its file storage off Amazon S3 onto custom infrastructure, reporting savings that its S-1 filing put at roughly $75 million over two years.
Durability vs Availability
Two different storage guarantees — whether data survives, and whether it can be reached right now — routinely conflated because both are quoted in nines.
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.
File-Based Integration
Exchanging data as files on a schedule via SFTP or shared storage — dated, still ubiquitous, and workable when its failure modes are handled explicitly.
Hot Partition
One partition receiving disproportionate traffic, so the system saturates at a fraction of its aggregate capacity.
Instance Family
A group of instance types sharing a resource profile — general purpose, compute optimised, memory optimised, storage optimised, accelerated — chosen by which resource the workload…
Lakehouse Table Format
A metadata layer over object storage that adds atomic commits, snapshots and schema evolution to files that otherwise have none.
Local First Write
Committing to local storage first and treating the server as an eventual replica, which makes the interface responsive and connectivity an optimisation.
OLTP vs OLAP
Two workload shapes with opposite requirements — many small indexed transactions versus few large scans and aggregations — which is why they belong in different stores.
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.
Partial Index
An index built over only the rows matching a predicate, so it is far smaller and cheaper to maintain than a full index.
Pod
The smallest deployable unit in Kubernetes — one or more containers that share a network namespace, storage volumes and a lifecycle, scheduled together on one node.
Retention Cost
The storage bill for keeping a log replayable, which is set by retention multiplied by throughput multiplied by the replication factor.
Scale Cube
A model describing three independent axes of scaling — cloning, functional decomposition, and data partitioning — each addressing a different limit.
Sharding
Splitting one dataset across multiple independent databases by a partition key, so that each holds a disjoint subset.
Uber's H3 Spatial Index
Uber indexes the world with hexagons rather than squares, because uniform neighbour distance makes supply, demand and pricing computations correct as well as fast.
Wide-Column Store
A store organised as partitions of sorted rows, designed for very high write throughput and predictable single-partition reads at large scale.
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
Design the network layout for a three-tier application in one cloud region. What are the decisions you cannot easily change later?
What the interviewer is testing Whether you know which network decisions are cheap and which are effectively permanent. This is a knowledge question with a clea
Netflix built its own CDN; Dropbox moved storage off S3. Both are usually wrong. What conditions made them right, and how do you test for those conditions?
What the interviewer is testing Whether you can extract the conditions from a famous decision rather than the decision itself. These two cases are the most comm
A multi-tenant SaaS product has outgrown one database. You must shard. How do you choose the partition key, and what makes this decision so expensive to get wrong?
What the interviewer is testing Whether you exhaust cheaper options first, and whether you understand that a shard key is close to irreversible. First: do not s
Design a URL shortener handling 100 million new links per month and 10 billion redirects. Where is the real difficulty?
What the interviewer is testing The classic warm up. What is being assessed is not whether you can shorten a URL — it is whether you do capacity arithmetic befo
Discord stores trillions of messages. What is their partition key, and what problem does the second half of it solve?
The key (channel id, bucket) — where bucket is a fixed time window. What each half does channel id matches the read pattern. Clients read messages within a chan
Three designs need distributed locks: a nightly report, a per-customer state machine, and a global config reload. For each, is a lock the right answer?
The nightly report — a lock is acceptable Purpose: efficiency . Two instances generating the same report wastes compute and possibly sends two emails, but nothi
Storage Layout & Partitioning
Partition keys, clustering, and the scan the query planner is left able to skip.
Cloud Storage
Object, block and file storage, and the access patterns each suits.
Partitioning & Sharding
Splitting data across machines, and the one-way door of a partition key.
Storage Costs
Tiering, lifecycle policies, retrieval charges and minimum durations.
Bulkheads & Isolation
Partitioning resources so one dependency cannot starve the others.
Data Lakes & Lakehouses
Open formats on object storage with transactional metadata on top.
Data Platform Tenancy
Multiple domains on shared storage and compute, with separable access and cost.
Frontend Security
CSP, XSS, CSRF, token storage, and the trust boundary that ends at the browser.
Open Table Formats
Iceberg, Delta and Hudi — transactions, snapshots and time travel over object storage.