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Cypher multihop: expand direct variable-length support beyond endpoint-only patterns #973

Closed
#1328
Closed
Cypher multihop: expand direct variable-length support beyond endpoint-only patterns#973
#1328

Description

@lmeyerov
lmeyerov
opened on Mar 30, 2026

Current state

Direct Cypher now supports the narrow endpoint-only single variable-length relationship subset, for example MATCH (a)-[*2]->(b) RETURN b and typed/reverse/undirected variants.

Latest tests also make the remaining boundaries explicit:

  • bounded/exact variable-length WHERE pattern predicates still fail fast
  • mixed connected patterns where the variable-length relationship is not the only relationship in the connected pattern still fail fast
  • named-path / path-value semantics remain separate work

Relevant coverage today:

  • graphistry/tests/compute/gfql/cypher/test_lowering.py::test_string_cypher_failfast_rejects_bounded_variable_length_where_pattern_predicates
  • graphistry/tests/compute/gfql/cypher/test_lowering.py::test_string_cypher_failfast_rejects_nonterminal_variable_length_relationship_patterns

Why track this separately

This is narrower than the broader GFQL path-semantics issue and is the next direct-Cypher parity step after the landed endpoint-only multihop subset.

Related but intentionally separate:

  • #722 covers broader path naming / path tracking / path-sensitive predicate semantics
  • #950 covers non-string params= research and is unrelated here

Desired scope

Expand direct Cypher variable-length support for the next user-visible families:

  1. Positive bounded/exact variable-length WHERE pattern predicates, for example:
  • MATCH (n) WHERE (n)-[:R*2]-() RETURN n
  • MATCH (n) WHERE (n)<-[:R*1..2]-() RETURN n
  1. Connected patterns where the variable-length relationship is not the only relationship in the connected pattern, for example:
  • MATCH (a)-[:LIKES*2]->()-[:LIKES]->(c) RETURN c.name
  • MATCH (a)-[:LIKES]->()-[:LIKES*3]->(c) RETURN c.name

Non-goals for this issue

Keep these out of scope unless they fall out cleanly:

  • named path alias materialization like RETURN p
  • path-value operators like length(p) / relationships(p)
  • relationship alias list-carrier semantics like RETURN r or count(r)
  • zero-hop *0 / *0..n forms unless explicitly designed

Success criteria

  • parser/lowering/runtime accept the targeted direct-Cypher shapes above
  • focused tests cover exact/ranged WHERE predicates and mixed connected patterns
  • unsupported named-path / path-value cases continue to fail fast with explicit validation errors unless intentionally implemented
  • user-facing docs are updated to widen the supported direct-Cypher multihop boundary accurately

Activity

  1. lmeyerov commented on Mar 30, 2026

    @lmeyerov
    lmeyerov
    on Mar 30, 2026
    ContributorAuthor

    While testing official SNB Interactive query shapes from pyg-bench, I hit the zero-hop open-range case *0.. used by IS2. Since this issue explicitly leaves zero-hop forms out of scope, I opened #983 to track that gap separately.

  2. lmeyerov
    added 11 commits that reference this issue on Mar 31, 2026

    feat(cypher): support variable-length rels in connected patterns (#973)

    aafaa99

    fix(cypher): correct range-hop pruning and empty graph guard (#973)

    bd948e6

    test+docs(cypher): add connected varlen tests, GPU validation, change…

    aefbdb5

    feat(cypher): support variable-length rels in connected patterns (#973)

    3253b8a

    fix(cypher): correct range-hop pruning and empty graph guard (#973)

    6d898c0

    test+docs(cypher): add connected varlen tests, GPU validation, change…

    adc3f3b

    feat(cypher): support variable-length rels in connected patterns (#973)

    8f07ba4

    fix(cypher): correct range-hop pruning and empty graph guard (#973)

    9994c60

    test+docs(cypher): add connected varlen tests, GPU validation, change…

    0be947a

    docs(changelog): move #973 entry to Development, add CI timeout note

    f68cd87

    feat(cypher): support variable-length rels in connected patterns (#973)…

    ffc5d35

  3. lmeyerov commented on Apr 2, 2026

    @lmeyerov
    lmeyerov
    on Apr 2, 2026
    ContributorAuthor

    Benchmark clarification from current-master dgx-spark rerun on 14dafaf6b951954d8de840f9236f3e874249ebac:\n\n- interactive-short-6 / message-forum no longer reproduces as a direct-Cypher blocker on current master\n - artifact: results/runs/dgx-spark-snb-interactive-is6-origin-master-14dafaf6b9-fresh-r1/\n - direct Cypher status: ok\n - direct_query_latency_ms = 28984.047\n- GFQL in the same run remains partial under #880, but the old benchmark-side claim that message-forum direct Cypher was still blocked by #973 is now stale.\n\nSo #973 may still matter for other shapes, but interactive-short-6 should be removed from the active benchmark blocker examples on current master.

  4. lmeyerov commented on Apr 4, 2026

    @lmeyerov
    lmeyerov
    on Apr 4, 2026
    ContributorAuthor

    Benchmark update from pyg-bench (2026-04-04, origin/master 14dafaf6b9):

    message-forum / interactive-short-6 direct Cypher is no longer an active benchmark blocker on current master.

    Measured artifact: results/runs/dgx-spark-snb-interactive-is6-origin-master-14dafaf6b9-fresh-r1/

    This lane is no longer in the active direct-Cypher benchmark blocker queue. The remaining open item on IS6 is the GFQL joined-row materialization workaround under #880.

  5. lmeyerov commented on May 7, 2026

    @lmeyerov
    lmeyerov
    on May 7, 2026
    ContributorAuthor

    Meta update: child issue #1001 is now closed via merged PR #1329.

    Update details:

    • Added exact-result + split-vs-connected parity regressions for the two-MATCH reentry varlen shapes (match5-25/26 family)
    • This hardens the already-supported behavior and prevents wrong-row regressions

    Remaining #973 scope is still the broader expansion items (notably bounded/exact variable-length WHERE pattern predicates and other boundary work listed in this meta issue).

  6. lmeyerov
    added a commit that references this issue on May 7, 2026

    Tests: amplify #973 bounded varlen WHERE coverage

    0b9c152
  7. lmeyerov
    closed this as completedin #1328on May 7, 2026
  8. lmeyerov
    added a commit that references this issue on May 7, 2026

    #973: expand direct-Cypher varlen WHERE support beyond endpoint-only (#…

    557acde

  9. lmeyerov commented on May 7, 2026

    @lmeyerov
    lmeyerov
    on May 7, 2026
    ContributorAuthor

    Land receipt: merged via #1328 on 2026-05-07.\n\nFollow-through completed before merge:\n- review-skill convergence artifacts under plans/issue-973/\n- targeted blackbox + whitebox amplification around bounded/exact varlen WHERE predicates\n- CI green, including tck-gfql on the merge head.

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