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Generate different sliding window candidates #556
Description
Sub-issue of #554.
Scope: the mechanism for producing valid sliding-window (W, S) candidate combinations for a given query/AQE — the "which window sizes and slide intervals are even legal here" question, separate from actually serving queries against them (#554's other sub-issue).
optimizer/candidate_gen.rs's window_candidates() (candidate_gen.rs:104-151) already does this conceptually for the offline cost-model/optimizer path (enumerating (WindowType, W_ms, slide_interval_ms, n_windows) tuples with the S | W, S | t_repeat_gcd, S < W constraints), but it's only reachable from the offline candidate_gen_dump/optimizer_cli cost simulators, not from the live planner path.
Needs its own design session — not scoped further here. See #554 and the design docs linked there for context.
Activity
milindsrivastava1997 commentedon Aug 20, 2026
Didn't realize. This is already implemented in candidate_gen.rs
milindsrivastava1997 commentedon Aug 27, 2026
Cross-window compatibility requirement from the #554/#557 scoping session:
When a Sliding value aggregation uses a
DeltaSetAggregatorfor key resolution, the DeltaSetAggregator must remain Tumbling-only. Let:W= Sliding valuewindow_size_msS= Sliding valueslide_interval_msD= Tumbling DeltaSetAggregatorwindow_size_msThe candidate is compatible only when both conditions hold:
D % S == 0— every DeltaSet bucket boundary lies on the Sliding value grid.W % D == 0— DeltaSet buckets exactly partition each Sliding value window.This relies on both grids sharing the existing Unix-epoch phase/alignment. If either divisibility condition fails (or the phases can differ), candidate generation/validation must reject the pairing loudly rather than allow a query-time partial or misaligned composition.
For Sliding
SetAggregator, the v1 rule remains stricter: it should share the value aggregation’s Sliding window size, slide interval, and grid phase. This exception is specifically for the Tumbling-onlyDeltaSetAggregatorrequired by #588/#606.