promql: add limit_ratio aggregation operator - #443
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v0.9.0 adds grammar rules for limitk and limit_ratio in the aggregate_op production. v0.8.0 declared these as `%expect-unused` tokens but never bound them in the grammar, so `limitk(...)` queries failed at parse time before this bump. The bump also widens the token id type from u8 to u16. Updated two local helper signatures (aggregate_op_name, binary_op_kind) to match. No behavior change.
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This PR adds first-class evaluator support for the limitk aggregation. It hooks AggregateOp::Limitk into the aggregation evaluation path with Prometheus-compatible grouping and filter-shape output. - implement limitk via AggregateKind::Limitk(i64), reusing the topk/bottomk per-group heap as a fixed-capacity push-only buffer (no eviction) - walk inputs in fingerprint-sorted order so selection is stable per query (Blake3 fingerprint already on SeriesSchema; diverges from upstream's xxhash) - extend lower_aggregate's shared K-param block to T_TOPK | T_BOTTOMK | T_LIMITK - extend physical-plan filter-shape to include Limitk - add limitk-focused operator tests covering by/without grouping, k=0/-1/k>n, mixed validity, multi-step independent selection, fingerprint-sort correctness, and out-of-order tile arrival - add limitk parity fixtures in aggregators.test (cardinality assertions; full label assertions where output is fully determined)
This PR adds first-class evaluator support for the limit_ratio aggregation. Inclusion is per-series via labelset hash: r >= 0 includes series whose hash < r; r < 0 includes hash >= 1 + r. r and r-1 partition the input. - implement limit_ratio via AggregateKind::LimitRatio(f64) on the absorb-then-finalise breaker path - compute per-series [0, 1) hash from the upper 64 bits of the u128 labelset fingerprint - widen param_values storage from i64 to f64 so the same scalar-param path serves both k (cast to i64 in k_for_step) and r (read directly in r_for_step) - extend lowering and physical planning to recognize limit_ratio (literal r and scalar(...) param both supported) - add limit_ratio operator tests covering extreme r, NaN r, negation-symmetric partition, per-series consistency across steps, validity skipping, dynamic r, and tile-arrival - add limit_ratio parity fixtures to aggregators.test (cardinality assertions; negation-symmetric sum)
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Summary
Adds evaluator support for
limit_ratiowith Prometheus-compatible grouping and filter-shape output.aggregators.testRelated Issues
Fixes #88
Stacked on
#442 — limitk. This PR's diff will include the limitk commits until #442 lands; rebase after.
Test Plan
cargo test -p opendata-timeseries --lib(825 pass)cargo clippy -p opendata-timeseries --lib --all-targets -- -D warningscargo fmt --checkChecklist
cargo fmtandcargo clippypass