Terminology

454 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 areas454 Architecture Fundamentals16 Distributed Systems73 Data Architecture71 Cloud Architecture55 Networking13 API & Integration Architecture17 Reliability & Resilience16 Observability14 Performance & Capacity Engineering13 Security Architecture50 Cost Architecture & FinOps12 Business Architecture9 Architecture Communication8 Enterprise Architecture8 Legacy Modernization11 AI-Era Architecture15 Software Architecture & Engineering19 Architecture Patterns15 Architecture Decision-Making11 The Architect's Meta-Skills8

Kind Any concept166 practice107 pattern93 case-study26 tool26 protocol22 metric14

28 terms shown.

Term	Kind	Topic	What it is
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 Stampede Dog-piling, Thundering Herd on Cache	concept	Cache Invalidation	Many concurrent requests missing on the same expired key and all recomputing it simultaneously, converting one expiry into a load spike.
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.
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.
Data Lakehouse	concept	Data Architecture	A pattern that puts warehouse-style transactions, schema and governance on top of cheap open-format object storage.
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.
Database Index	concept	Data Architecture	A secondary structure that lets the engine find rows without scanning, trading write cost and storage for read speed.
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.
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.
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.
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.
OLTP vs OLAP	concept	Data Warehousing	Two workload shapes with opposite requirements — many small indexed transactions versus few large scans and aggregations — which is why they belong in different stores.
Operational vs Analytical Store	concept	Polyglot Persistence	The separation between the store serving the application's transactions and the one serving reporting and analysis, and the mechanism connecting them.
Partial Index Filtered Index	concept	Indexing	An index built over only the rows matching a predicate, so it is far smaller and cheaper to maintain than a full index.
Query Plan Execution Plan, EXPLAIN	concept	Data Architecture	The database's chosen strategy for executing a query, and the first thing to look at when one is slow.
Right to Erasure Right to be Forgotten	concept	Data Lifecycle & Retention	A data subject's right to have their personal data deleted, and an obligation that reaches every copy an architecture has created.
Schema Evolution	concept	Data Lakes & Lakehouses	Changing a table's structure over time while keeping existing data readable and existing consumers working.
Stream-Table Duality	concept	Streaming Data	The equivalence between a stream of changes and a table of current state — each can be derived from the other.
Surrogate Key Synthetic Key	concept	Relational Modelling	A system-generated identifier with no business meaning, used as the primary key instead of a naturally occurring business value.
Synchronous vs Asynchronous Replication	concept	Replication	Whether a write is acknowledged only after a replica has it, trading write latency against the amount of data a failure can lose.
Time Travel Data Versioning, Snapshot Query	concept	Data Lakes & Lakehouses	Querying a table as it existed at a previous version or timestamp, made possible by keeping the metadata and files of prior commits.
Watermark	concept	Streaming Data	A moving assertion that no events older than a given event-time will arrive, which is what allows an event-time window to be closed and emitted.
Windowing	concept	Streaming Data	Grouping an unbounded stream into finite chunks so aggregation can produce results, defined over event time rather than arrival time.
Write Skew	concept	Transactions & Isolation	An anomaly where two transactions each read a set of rows, make disjoint writes based on what they read, and together violate an invariant neither could have broken alone.
Write-Ahead Log WAL, Commit Log	concept	Data Architecture	Recording every change to a durable sequential log before applying it, so that a crash can be recovered by replaying the log.