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gfql polars: the plain single-hop chain branch ignores prune_to_endpoints (pandas keeps only the arrival side) #2053
Description
Summary
Route-level sibling found while hoisting the chain admission predicates: the pandas/cuDF chain fast path declines prune_to_endpoints=True ("prune keeps only the arrival side → full path"), but the polars chain's plain single-hop branch admits the shape and returns both endpoints plus the edges, so polars and pandas disagree.
Repro
import pandas as pd, polars as pl, graphistry
from graphistry.compute.ast import n, e_forward
nodes = pd.DataFrame({"key": [1, 2, 3, 4, 5], "id": [10, 20, 30, 40, 50]})
edges = pd.DataFrame({"s": [1, 1, 2, 3, 3, 4], "d": [2, 3, 3, 1, 1, 5], "eid": range(6)})
ops = [n({"key": 1}), e_forward(prune_to_endpoints=True), n()]
graphistry.nodes(nodes, "key").edges(edges, "s", "d", "eid").gfql(ops) # nodes [2, 3], no edges
graphistry.nodes(pl.from_pandas(nodes), "key").edges(pl.from_pandas(edges), "s", "d", "eid").gfql(ops, engine="polars") # nodes [1, 2, 3], edges [0, 1]Unseeded [n(), e_forward(prune_to_endpoints=True), n()]: pandas [1, 2, 3, 5], polars [1, 2, 3, 4, 5].
Expected
Either the polars plain branch declines prune_to_endpoints like the pandas gate (polars_plain_single_hop_admits is the single place to do it once the predicate refactor lands) or it implements the arrival-side contract; both engines must agree.
Pins
A strict-xfail parity pin lives in graphistry/tests/compute/gfql/lazy/engine/polars/test_chain_admission.py over the shared route corpus and flips when this is fixed.
Activity
refactor(gfql): chain hot paths expose their shape admission predicates
refactor(gfql): chain hot paths expose their shape admission predicates
refactor(gfql): chain hot paths expose their shape admission predicates
lmeyerov commentedon Sep 6, 2026
Scope update from the route harness (#2061): the divergence is not only the plain single-hop branch. With every hot path declined (
GFQL_ROUTES_OFF=all, pygraphistry's test-side route switch), the polars general traversal returns the same rows as the plain branch, so the polars engine as a whole ignoresprune_to_endpointswhile pandas keeps only the arrival side.Probe on the issue's frames (
[n({"key": 1}), e_forward(prune_to_endpoints=True), n()]):Unseeded
[n(), e_forward(prune_to_endpoints=True), n()]: pandas general [1, 2, 3, 5], polars general [1, 2, 3, 4, 5] (plus the (4,5) edge).So declining the shape in
polars_plain_single_hop_admitswould only move the wrong answer from the lane to the full path. The fix is the arrival-side contract in the polars chain itself (or a typed decline until it exists). The harness pins this as a strict expected failure onpolars-plainkeyed by tag#2053(routes corpus + the pandas_BYPASS_SHAPESprune rows), so it flips when fixed.test(gfql): shape registry fed by the specialization tables + route h…
test(gfql): shape registry fed by the specialization tables + route h…
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
refactor(gfql): chain hot paths expose their shape admission predicates
test(gfql): shape registry fed by the specialization tables + route h…
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
refactor(gfql): chain hot paths expose their shape admission predicates
2 remaining items
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
refactor(gfql): chain hot paths expose their shape admission predicates
test(gfql): shape registry fed by the specialization tables + route h…
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
refactor(gfql): chain hot paths expose their shape admission predicates
test(gfql): shape registry fed by the specialization tables + route h…
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
refactor(gfql): chain hot paths expose their shape admission predicates
test(gfql): shape registry fed by the specialization tables + route h…
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
fix(gfql): polars declines prune_to_endpoints on every hop shape (#2053)
Merge pull request #2062 from graphistry/fix/gfql-2058-general-path-i…
lmeyerov commentedon Oct 3, 2026
Closing: fixed by #2065. Its "Closes #2053" did not fire because the PR merged into a stacked base (
fix/gfql-2058-general-path-int-dtypes) and the stack was re-landed under new SHAs, so GitHub never saw it reach master; the content is on master —test_prune_to_endpoints_is_a_typed_decline_on_polars_and_served_on_pandasand theprune_to_endpointsadmission guard inchain_specializations/admission.py. Polars declines single-hopprune_to_endpointswith a typed error instead of ignoring it.