Window partition
A window partition is an independent subset of rows defined for separate evaluation by a window function.
DuckDB in Action
The PARTITION BY clause divides the input rows of a window function into groups that are processed independently.
- How it is used
- Calculates rankings and aggregates independently within categories while preserving one output row per input row.
- How deep it goes
- Explains independent partitions, visibility boundaries, ordering, ranking, and aggregates, but does not detail frame specifications.
- Examples
- Uses power readings to demonstrate top-three and top-two rankings, plus per-system average daily production.
- What you can do after
- Apply it via SQL to rank rows or calculate partition-specific aggregates without reducing the result to grouped rows.
Just Use Postgres!
A PARTITION BY clause divides rows processed by a window function into independent groups based on specified expressions.
- How it is used
- Uses partitioning to calculate per-group values while retaining detailed rows in streaming-play queries.
- How deep it goes
- Explains grouping, CTE evaluation, duplicate removal, and ordered running frames, but does not cover broader window-function internals.
- Examples
- Demonstrates per-song play totals, repeated totals beside users, and running totals ordered by user ID.
- What you can do after
- Apply it via SQL to compute independent group totals and ordered cumulative results without collapsing detail rows.
Related concepts
- lagused by · A lag is a temporal or positional offset that associates an observation with an earlier observation in an ordered sequence or time series.
- database tablepart of · A database table is a relational database structure that organizes records into rows and defined columns.
- window functionconfigures · A window function is an SQL operation that computes a value over related rows while preserving each individual row in the result.
- over clausepart of · An OVER clause defines the partitioning, ordering, and frame specification that determines the rows processed by a SQL window function.
- partitionkind of · A partition is a collection of pairwise disjoint nonempty subsets whose union is the set or space being divided.
- partitionkind of · A partition is a distinct subdivision of a larger data, storage, or work unit that can be stored, managed, or processed separately.
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