Resource limits and current boundaries

Sessions default to 256 path hops and 256 MiB of DataFusion tracked operator memory per statement. Configure subsequent statements with Session::set_query_limits.

use graphfusion::QueryLimits;
session.set_query_limits(QueryLimits {
    max_path_hops: 64,
    memory_limit_bytes: 128 * 1024 * 1024,
})?;

The memory budget is not a process RSS cap. It does not account for every imported graph buffer, optional/input barrier or final materialized result. Resource exhaustion is an error, following normal statement/transaction rollback behavior.

Path completeness

A finite path bound above the hop limit fails during planning. The planner does not substitute the configured limit and return a silently truncated answer. It combines bounds across concatenation, alternatives, repetition and whole-path modes.

Some unbounded forms obtain complete finite bounds from graph cardinality or restricted selective-WALK proofs. General history-dependent or compositional repeatable unbounded patterns are unsupported. Use a finite upper bound when those proofs do not apply.

Candidate enumeration currently happens before path ranking. Dense graphs, parallel edges and repeated groups can produce many candidates even for a shortest-path request. RETURN LIMIT caps output, not enumeration work.

Storage and API

• Graph updates materialize and rewrite the complete affected graph.
• Results are materialized; no streaming/prepared query API is exposed.
• Metadata records have a 64 MiB limit; unsupported definition nesting is rejected before publication.
• Persistent statement startup reloads recovery metadata and validates Parquet footers.
• Typed graph data operations, indexes, incremental file deltas and format migrations are not implemented.

The support matrix separates these execution limits from parser coverage.