Filtering

Narrow traversal streams with predicates and exact search candidate sets

Guide

HelixDB filters in two places:

• A source predicate such as nWhere / n_where selects the initial candidates. It is eligible for index push-down, so filter here whenever you can.
• .where(...) filters the current stream at any later point in a traversal, for example after following an edge.

Both accept the same predicates. To restrict vector or full-text search to a candidate set, see Filter search candidates.

Common predicates

Intent	Builder
Equality	eq(property, value)
Comparison	gt, gte, lt, lte
Inclusive range	between
Set membership	isIn / is_in
Property exists	hasKey / has_key
Prefix	startsWith / starts_with
Boolean composition	and, or, not

Values can be literals or typed parameter expressions.

Filter a stream

Rust

g()
    .n_with_label("User")
    .where_(Predicate::gte("score", 100))
    .value_map(Some(vec!["$id", "name", "score"]))

Filter search candidates

To restrict vector or full-text search to a candidate set, build the traversal that decides membership and search within it. Do not filter search results afterward with .where(...): excluded high-ranking hits still consume the top k. See Prefiltered search.

Vector prefiltering

See Vector prefiltering.

Full-text search prefiltering

See Full-text search prefiltering.

Next steps

Typed parameters

Move request-specific filter values out of the AST.

Secondary indexes

Back equality and range predicates with an index.

Prefiltered search

Rank only the records a traversal reaches.