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275 questions, 991 terms and 600 topics in 30 areas.
50 results for “Open Table Formats”
Lakehouse Table Format
A metadata layer over object storage that adds atomic commits, snapshots and schema evolution to files that otherwise have none.
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.
Half-Open State
The circuit breaker state that allows a limited number of trial requests through to test whether a failed dependency has recovered.
Netflix Open Connect
Netflix built its own CDN and placed appliances inside ISP networks, turning the most expensive part of its cost structure into hardware it controls.
Nines Table
The mapping between availability percentages and permitted downtime, and the cost curve that comes with it.
Route Table
The set of rules deciding where traffic leaving a subnet is sent, and the thing that actually makes a subnet public or private.
Stream-Table Duality
The equivalence between a stream of changes and a table of current state — each can be derived from the other.
Binary Serialisation
Encoding messages compactly using a schema rather than as self-describing text, trading readability for size and parse speed.
Changelog Stream
A stream whose records are keyed updates, so replaying it from the beginning reconstructs a table — the same information in the other of its two forms.
Covering Index
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
A pattern that puts warehouse-style transactions, schema and governance on top of cheap open-format object storage.
Data Lineage
A record of where each dataset came from, what transformed it, and what depends on it — traced at table and ideally column level.
Fallback Strategy
What a caller does instead when a circuit breaker is open — the part of the pattern that determines whether failing fast helps anyone.
Foreign Key Constraint
A database-enforced rule that a referencing value must exist in the referenced table — referential integrity that no application bug can violate.
Grain Declaration
Stating exactly what one row of a fact table represents, before any column is chosen, because every later decision depends on it.
Indexing Strategy
Choosing the set of indexes a table carries by working backwards from its actual queries, and accepting the write cost that each one adds.
InnerSource
Applying open-source collaboration practices inside an organisation, so that teams can contribute to code they do not own rather than waiting or duplicating.
Message Translator
A component converting a message between two systems' formats, so neither has to adopt the other's model.
Model Context Protocol
An open protocol that standardises how AI applications connect to external tools, data sources and prompts.
Operational Data Push
Sending modelled analytical data back into operational tools, which turns a warehouse table into a production dependency with none of the guarantees.
Outbox Pattern
Writing an outgoing message into a table in the same transaction as the business change, and relaying it to the broker separately, so the two cannot diverge.
Outbox Relay
The process that reads pending messages from an outbox table and publishes them to a broker, providing at-least-once delivery with no distributed transaction.
Predicate-Based Filtering
A policy that appends a filter to every query on a table based on who is asking, so one physical table serves many audiences safely.
Route Propagation
Automatically inserting routes learned from a VPN or dedicated connection into a route table, rather than maintaining them by hand.
SOLID
Five object-oriented design principles — single responsibility, open/closed, Liskov substitution, interface segregation, dependency inversion.
Schema Evolution
Changing a table's structure over time while keeping existing data readable and existing consumers working.
Small File Problem
The degradation that follows from many tiny files — metadata operations dominating, compression failing, and columnar formats losing their advantage.
Source NAT
Rewriting the source address of outbound packets so that many private addresses share one public address, with a translation table mapping replies back.
Star Schema
A dimensional model with one central fact table of measurements surrounded by denormalised dimension tables describing them.
Stream Enrichment
Attaching reference data to a stream by lookup against a materialised table rather than by joining two unbounded streams.
Time Travel
Querying a table as it existed at a previous version or timestamp, made possible by keeping the metadata and files of prior commits.
Transaction Log Stream
Change events derived from a database's write-ahead log — faithful to the table's mutations and to its internal model rather than to the business's.
XA Transaction
The X/Open standard interface for two-phase commit across heterogeneous resource managers, still common in enterprise middleware and rarely the right choice for new services.
A team is choosing between Iceberg, Delta and Hudi for a new lakehouse. How would you approach the decision?
The formats are more alike than the debate suggests All three provide the same core: atomic commits over object storage, snapshots and time travel, schema evolu
A dashboard has been wrong for three weeks. Nobody knows which upstream produced the table it reads. What is the governance failure, and what fixes it?
The failures, and there are three 1. No lineage. The question "which upstream produced this?" should be answerable in seconds by following a derived dependency
A dashboard query that took 200ms now takes 40 seconds. The table has grown to 200 million rows. Walk me through diagnosis and fix, including what you would not do.
What the interviewer is testing Whether you diagnose with evidence before changing anything, and whether you know the costs of the fixes you propose. Diagnosis,
A finance report double-counts revenue after a new fact table is added. What is the likely modelling error?
The likely error: a fan out join between fact tables at different grains The classic mechanism. You have an order lines fact at line grain and a shipments fact
A logic bug means six months of a derived table are wrong. You must reprocess without disrupting live consumers. How?
Establish the blast radius first Which downstream tables, reports and extracts consumed the wrong data, and did any of it leave the organisation — a regulatory
A table has 14 indexes and writes have become slow. How do you decide which to remove?
The approach 1. Get usage statistics, not opinions. Every major engine reports index scan counts — PostgreSQL's pg stat user indexes , SQL Server's sys.dm db in
A warehouse table now feeds the CRM through reverse ETL. It breaks, and the analytics team and the CRM team each say it is the other's problem. How do you resolve it?
The dispute is a design gap, not a personality problem A warehouse table built for analysis — nightly latency, best effort availability, schema changes made by
Open Table Formats
Iceberg, Delta and Hudi — transactions, snapshots and time travel over object storage.
Data Lakes & Lakehouses
Open formats on object storage with transactional metadata on top.
File Formats & Compaction
Columnar formats, the small-file problem, and the maintenance nobody schedules.
Message Formats
JSON, Protobuf, Avro — schema evolution and payload economics.
Stream-Table Duality
A changelog and a table as two views of the same thing, and materialising between them.
Build vs Buy
Differentiation versus table stakes, priced over five years.
InnerSource
Open-source collaboration practices applied inside an organisation.
OpenTelemetry
Instrumenting once against an open standard rather than a vendor agent.
Regulatory Reporting Pipelines
Submissions with fixed deadlines, fixed formats, and a regulator who audits the lineage.
Row & Column-Level Security
Restricting slices of a table rather than the whole table, and where it is enforced.