Terminology

2185 terms, tools, patterns and metrics an architect is expected to use precisely. Each one gets a short explanation of what it is, and — where it matters — what it is commonly confused with. Search filters as you type; the column headers sort.

All areas2185 Architecture Fundamentals77 Distributed Systems107 Data Architecture110 Cloud Architecture89 Networking88 API & Integration Architecture82 Reliability & Resilience75 Observability70 Performance & Capacity Engineering72 Security Architecture81 Cost Architecture & FinOps66 Business Architecture67 Architecture Communication67 Enterprise Architecture66 Legacy Modernization66 AI-Era Architecture69 Software Architecture & Engineering71 Architecture Patterns71 Architecture Decision-Making63 The Architect's Meta-Skills61 Delivery & Release Engineering66 Platform Engineering & Developer Experience70 Testing & Quality Architecture66 Data Platform Architecture64 Streaming & Real-Time Data69 Data Governance & Semantics69 Frontend & Experience Architecture66 Edge, Mobile & IoT68 Regulatory & Data Protection Architecture65 Assurance, Audit & Model Risk64

Kind Any concept785 practice729 pattern362 metric125 case-study77 tool62 protocol45

110 terms shown.

Term	Kind	Topic	What it is
Bloom Filter	tool	Data Architecture	A compact probabilistic structure that answers "is this key definitely absent, or possibly present?" — no false negatives, tunable false positives.
Bloom Filter Cache Guard	pattern	Caching Strategies	Placing a Bloom filter in front of an expensive lookup so that keys which certainly do not exist never reach it.
Cache Invalidation	concept	Data Architecture	The problem of removing or refreshing cached data when the underlying source changes, and the reason caching is harder than it looks.
Cache Penetration	concept	Cache Invalidation	Repeated lookups for keys that do not exist, which miss the cache every time by definition and pass straight through to the store.
Cache-Loss Survivability Cache Failure Blast Radius, Origin Protection	practice	Cache Invalidation	Designing so that losing the cache degrades the system rather than destroying it - because a cache absorbing most of the read traffic is a capacity dependency, not an optimisation.
Caching Strategies	pattern	Caching Strategies	Which cache pattern to use, how staleness is bounded, and the failure modes that only appear under load.
Caching Strategies in Practice Cache-Aside, Write-Through, Read-Through	pattern	Caching Strategies	The write and read strategies, the stampede that takes down origins, and why cache invalidation deserves its reputation.
Cardinality Estimation	concept	Query Optimisation	The planner's prediction of how many rows each step of a query will produce — the input that determines every other choice it makes.
CDC Initial Snapshot	concept	Change Data Capture	The consistent full copy taken when a CDC pipeline starts, before streaming begins — and the step that determines whether the target is correct.
Change Data Capture CDC	pattern	Data Architecture	Publishing a stream of a database's row-level changes by reading its replication log, without modifying the application that owns it.
Change Data Capture in Practice CDC	pattern	Change Data Capture	Turning a database's replication log into an event stream, so downstream systems learn about changes without the application publishing them.
Claim Provenance As-Of Metadata, Source-Tagged Data	practice	Data Architecture	Storing every externally sourced value with its timestamp, its source and a confidence derived from that source's history - so that downstream decisions about staleness are explicit rather than accidental.
Consistent Hashing Ring Hashing	concept	Partitioning & Sharding	A partitioning scheme where adding or removing a node moves only a small fraction of keys, instead of remapping everything.
Covering Index Index-Only Scan	concept	Indexing	An index that contains every column a query needs, so the query is answered from the index without reading the table at all.
CQRS Command Query Responsibility Segregation	pattern	Data Architecture	Separating the model used to change state from the model used to read it, so each can be optimised independently.
CQRS as a Data Architecture	pattern	CQRS	Treating the serving layer as a derived, rebuildable projection of an authoritative write store.
Crypto-Shredding Cryptographic Erasure, Key Destruction Deletion, Per-Subject Encryption	pattern	Data Lifecycle & Retention	Encrypting each data subject's personal data under a key unique to them, so that a deletion request is satisfied by destroying the key rather than by rewriting immutable or widely-replicated data.
Crypto-Shredding Cryptographic Erasure	practice	Data Lifecycle & Retention	Making data permanently unreadable by destroying its encryption key, so immutable copies in backups and archives are erased without being modified.
Data Catalog	tool	Data Governance	A searchable inventory of datasets with their schema, owner, meaning, freshness, quality and classification.
Data Governance	practice	Data Governance	Making data ownership, meaning, quality and access explicit — the mechanism that keeps a data platform trustworthy as it grows.
Data Lakehouse	concept	Data Architecture	A pattern that puts warehouse-style transactions, schema and governance on top of cheap open-format object storage.
Data Lifecycle	practice	Data Lifecycle & Retention	Managing data from creation through tiering to deletion — the discipline that keeps storage cost and legal exposure bounded.
Data Lineage	practice	Data Governance	A record of where each dataset came from, what transformed it, and what depends on it — traced at table and ideally column level.
Data Mesh	concept	Data Architecture	An organisational approach that gives domain teams ownership of their analytical data as a product, with a self-serve platform and federated governance.
Data Retention Policy	practice	Data Architecture	A defined rule for how long each class of data is kept, where, and what happens at the end of it.
Data Warehousing	concept	Data Warehousing	A separate analytical store modelled for questions rather than transactions, physically isolated from the systems that generate the data.
Database Index	concept	Data Architecture	A secondary structure that lets the engine find rows without scanning, trading write cost and storage for read speed.
Database per Service	pattern	Polyglot Persistence	Each service owning its own datastore, with no other service reading or writing it directly.
Denormalisation	practice	Data Architecture	Deliberately duplicating data across records to make reads cheap, accepting the write-time cost of keeping copies in step.
Derived Store Discipline One Authoritative Store Per Fact, No Dual Authority	concept	Polyglot Persistence	The rule that every fact has exactly one authoritative store and every other copy is explicitly derived, rebuildable and populated by a documented pipeline - the discipline that makes multiple datastores defensible.
Discord's Message Store Migrations	case-study	Data Architecture	Discord moved from MongoDB to Cassandra to ScyllaDB as message volume grew from millions to trillions, each time for a specific and different reason.
Discord: Hot Partitions at Trillions of Messages Discord Message Storage	case-study	Partitioning & Sharding	Discord partitions messages by channel and time bucket, because a single very busy channel would otherwise concentrate load on one partition.
Document Store	tool	NoSQL Stores	A store that keeps semi-structured documents — typically JSON — retrievable by key and queryable by their contents.
ETL and ELT	practice	ETL & ELT	Whether to transform before loading or after — a choice that follows from where compute is cheap and who owns the transformation.
ETL vs ELT	concept	Data Architecture	Whether data is transformed before loading into the target or after it, which decides where the compute happens and how much raw history you keep.
Event Sourcing	pattern	Data Architecture	Storing the full sequence of state-changing events as the system of record, and deriving current state by replaying them.
Event Sourcing in Practice	pattern	Event Sourcing	Storing state as an immutable sequence of events and deriving current state by replay — powerful where history is the domain, expensive everywhere else.
Event Store	tool	Event Sourcing	An append-only store of domain events organised into per-entity streams, serving as the system of record rather than as a log beside it.
Event Upcasting	pattern	Event Sourcing	Transforming an old event's stored form into the current shape as it is read, so historical events remain replayable after the schema changes.
Expand and Contract Migration Parallel Change, Expand-Migrate-Contract	practice	Data Governance	Changing a schema through a sequence of individually backward-compatible steps, so old and new application versions can run simultaneously.
Figma's Postgres Sharding	case-study	Data Architecture	Figma delayed sharding for years using replicas and vertical partitioning, then sharded Postgres horizontally without downtime using logical shards and a proxy layer.
Foreign Key Constraint	concept	Relational Modelling	A database-enforced rule that a referencing value must exist in the referenced table — referential integrity that no application bug can violate.
Freshness Tiering Hot Index, Recent-Document Tier	pattern	Indexing	Splitting a search corpus into a small aggressively-refreshed index of recent documents and a large lazily-refreshed main index, so sub-second freshness is paid for only on the documents that need it.
Graph Database	tool	NoSQL Stores	A store whose first-class citizens are nodes and the relationships between them, making multi-hop traversal cheap.
Hot Key Hot Partition, Hot Row, Key Skew, Celebrity Problem	concept	Partitioning & Sharding	A single key or narrow key range receiving a disproportionate share of traffic, so one partition saturates while the rest of the cluster is idle - the failure that no amount of horizontal scaling fixes.
Hot Key Hot Partition, Hot Shard	concept	Partitioning & Sharding	A single key or partition receiving a disproportionate share of traffic, so that a well-balanced key space still produces one overloaded node.
Hot Partition Hot Shard, Hot Key	concept	Partitioning & Sharding	One partition receiving disproportionate traffic, so the system saturates at a fraction of its aggregate capacity.
Hot, Warm and Cold Data	concept	Data Lifecycle & Retention	Classifying data by how frequently and how urgently it is accessed, so each tier can be stored on media priced for that access pattern.
Idempotent Pipeline	practice	ETL & ELT	A pipeline whose task can be re-run for the same input window any number of times and produce the same result.
Identity-Record Separation Pseudonymous Subject Reference, Retention-Erasure Split	pattern	Data Lifecycle & Retention	Holding regulated business records under a pseudonymous reference and the reference-to-person mapping in a separate governed store, so a retention obligation and an erasure right can both be satisfied.
Index Selectivity	metric	Indexing	The fraction of rows a predicate eliminates — the property that determines whether an index is worth using at all.
Indexing	concept	Indexing	Auxiliary structures that turn a scan into a lookup — the highest-leverage database intervention and the one most often applied blindly.
Indexing Strategy	practice	Data Architecture	Choosing the set of indexes a table carries by working backwards from its actual queries, and accepting the write cost that each one adds.
Integrated Cache Tier Cache-Behind-the-Client, Storage-Managed Cache, Transparent Cache	pattern	Caching Strategies	Placing the cache inside the storage layer's own client rather than in each calling application, so invalidation is driven by the change stream and consistency semantics are defined once instead of per team.
Join Strategies	concept	Query Optimisation	The three ways a database combines two row sets — nested loop, hash join and merge join — and the conditions under which each is correct.
Lakehouse	pattern	Data Lakes & Lakehouses	Open table formats over object storage that add transactions, schema enforcement and incremental updates to a data lake.
LinkedIn Databus: Change Capture as a Product Databus	case-study	Change Data Capture	LinkedIn built a change capture system so that derived stores — search, graph, caches — could stay current without every application dual-writing to them.
Log-Based CDC	pattern	Change Data Capture	Capturing changes by reading the database's own write-ahead log, which sees every change with no load on the source and no application involvement.
Materialised Read Model Projection, Read Model	practice	CQRS	A precomputed, query-shaped copy of data maintained asynchronously from the system of record - and the operational obligations that come with it.
Materialized View	pattern	Data Architecture	A precomputed, stored result of a query, refreshed on a schedule or from a change stream, read instead of recomputing.