Grouping

No Hidden Groups

Empty input rows do not invent buckets.

highlighted = computed this step

No hidden groups

An empty input table does not invent group buckets.

no rows, no buckets\text{no rows, no buckets}

Show the empty result

The input has 0 rows and produces 0 groups.

groups=0\text{groups}=0

Grouping examples are tiny finite table transforms; SQL dialects, NULLs, AVG/rounding, planner behavior, indexes, performance, and product behavior are out of scope.

No hidden groups: base rowssourceRowidkindqtynonenonenonenone group by columnscolumnkind aggregate specsopcolumnascount_rowsrowsn group bucketskeysourceRowsrowCountnonenonenone aggregate rowskeynnonenone having keep/dropkeystatusreasonnonenonenone output rowskeynnonenone group factsfactvaluerowCount0groupByColumnCount1groupCount0aggregateCount1outputGroupCount0havingnonehiddenGroupsno

Read none

The diagram prints none rows for empty tables so absence is explicit.

absence is visible\text{absence is visible}

Summary

There is no hidden book, game, or tool group when no row supplies that key.

no hidden groups\text{no hidden groups}