Repository navigation
PromQL: topk over cross-series aggregation (e.g. sum by) is unsupported #23
Description
Summary
topk applied to the output of a cross-series aggregation operator (e.g. sum by (...)) fails with an unsupported feature error. This is a valid and common PromQL pattern.
Reproduction
# P5 — topk over sum-by aggregation
topk(5, sum by (service) (http_requests_total))
Error:
ERR: unsupported feature: aggregate argument: Discriminant(0)
Expected
Should lower to Limit { Sort { Aggregate(Sum, by:[service]) { Scan } } } — the topk becomes a Sort+Limit over the inner aggregation result.
Reproduce via example
cargo run -p asap-control-lower --example topk_ir
Labels: P5
Activity
zzylol commentedon Jul 2, 2026
Verified fixed on latest
main(via PRs #28/#29, which added nested-aggregate lowering +ColumnRef::SampleValueresolution to the sole numeric column).topk(5, sum by (service) (http_requests_total))(P5) now lowers to exactly the Expected shape:No more
unsupported feature: aggregate argument. Reproduced viacargo run -p asap-control-lower --example topk_ir. Closing.