Aggregation
Everything on SkillVeris tagged Aggregation — collected across the glossary, study notes, blog, and cheat sheets.
13 resources across 2 libraries
Study Notes(6)
DAX Aggregation Functions
Aggregation functions like SUM, AVERAGE, COUNT, and their X-suffixed iterator counterparts are the workhorses for summarizing data in DAX measures.
Aggregation Performance
Learn what drives aggregation performance in Elasticsearch, doc_values, shard sizing, caching, and approximate algorithms, and how to keep large aggregations f…
Aggregation Performance
Learn practical techniques for diagnosing and improving the performance of MongoDB aggregation pipelines, from index usage to explain plans.
Common Aggregation Stages
A practical tour of the most frequently used aggregation stages — $match, $project, $sort, $limit, $skip, and $unwind — and how they reshape documents.
The Aggregation Pipeline
Learn how MongoDB's aggregation pipeline transforms documents through an ordered sequence of stages to filter, reshape, and summarize data.
Aggregation Functions
Explore the built-in and custom aggregation functions available after groupby, including agg() for applying multiple statistics at once.
Interview Questions(7)
HAVING vs WHERE Clause
WHERE filters individual rows before any grouping or aggregation happens, while HAVING filters groups after GROUP BY has aggregated them, so HAVING is the only…
What is the Difference Between GROUP BY and ORDER BY?
GROUP BY aggregates rows that share a common value into summary rows, while ORDER BY simply sorts the result set without changing how many rows are returned.
How Do You Design Document Schemas in MongoDB?
MongoDB document schema design means choosing, for each relationship in your data, whether to embed related data inside a single document or reference it from…
What Are Time-Series Databases and When Should You Use One?
A time-series database is a storage engine purpose-built for data points indexed by time, optimizing for high-volume append-only writes, time-range queries, an…
Aggregation vs Composition in OOP
Aggregation and composition are both "has-a" relationships between objects, but composition implies strict ownership where the part cannot outlive the whole, w…
UML Class Diagram Relationships Explained
A UML class diagram models a system’s classes as boxes with attributes and operations, and connects them with relationship lines — association, aggregation, co…
Association vs Aggregation vs Composition
Association is any structural relationship where one object refers to another, aggregation is a weak has-a where the contained object can exist independently,…