aggregate

The groups of query. The core plans the residual operators the storage declares RESIDUAL: it removes them from the query it sends down, asks for every group when an operator needs them all, and applies dense fill, windows, HAVING and top-N (or the limit) to the rows that come back. An aggregation without groups always has its summary row: when the backend emits none, because no record matched, the core emits the empty summary (EmptyAggregationValues). Such a query has no HAVING (the protocol requires a group for one, AggregationQuery rejects it at construction), so a storage's native HAVING can never be what removed a summary row; with groups, rows a HAVING removes are not replaced. When it reads every group, budget's QueryBudget.maxResidualGroups bounds how many it processes, dense fill rows included: HAVING can discard every fill row, so without counting them a sparse fine-grained dense histogram would generate rows until the timeout.