Data Virtualisation

Querying across sources without moving data, and the performance ceiling that imposes.

5Questions

6Flashcards

4Terms

Drill this topic All of Data Platform Architecture

Questions

5 to work through

intermediate

A federation layer serves 60 analysts across four sources: the lakehouse, a Postgres replica, a managed warehouse and a SaaS REST connector. At 11:40 the REST connector's upstream begins answering in 40 seconds rather than 200 ms. Nothing errors and nothing is down. Walk through what happens to the other analysts over the next ten minutes.

3 min answer
intermediate

A group holds customer data in separate EU and US entities, and the rows may not be copied across the border. The board wants one revenue dashboard. The team puts a federation layer over both regions and queries in place rather than consolidating. What has that bought, when does the bill arrive, and how do they keep the option to reverse it?

2 min answer
intermediate

A platform proposes querying operational databases directly rather than copying data. When does that work?

2 min answer
advanced

A BI tool queries the operational read replica directly through a federation layer, avoiding a copy. At 09:03 replica lag starts climbing. By 09:12 checkout p99 has tripled. By 09:30 the replica is 40 minutes behind and support is reporting stale order status. What failed, and which design decision allowed it?

3 min answer
advanced

A vendor proposes replacing your ingestion pipelines with data virtualisation — query everything in place, no copies. Assess it.

1 min answer

Terminology

4 terms in this topic

pattern

Data Virtualisation

Querying data where it lives across multiple systems through a single logical layer, without physically consolidating it.

concept

Predicate Pushdown

Sending a filter to the layer that holds the data rather than fetching rows and filtering afterwards, which is the difference between reading megabyt…

pattern

Query Federation

Executing a single query across several underlying systems without moving the data, and the performance ceiling that pushdown determines.

pattern

Source Load Budget

An explicit cap on the concurrency, rows and duration that analytical reads may consume on an operational source - so a dashboard query cannot become…

Data Platform Architecture