Function analyze

nodedb-sql/src/planner/bitmap_emit/predicate.rs:42–82

Inspect `plan` and return a `BitmapHint` if the plan qualifies for bitmap pushdown, or `None` if the plan should run without a prefilter. Only exact-match shapes on `Ready` indexed columns are considered. Ranges are never emitted (no statistics available to confirm selectivity).

(plan: &SqlPlan)

/// Only exact-match shapes on `Ready` indexed columns are considered.
/// Ranges are never emitted (no statistics available to confirm selectivity).
pub fn analyze(plan: &SqlPlan) -> Option<BitmapHint> {
    match plan {
        // Already a single-field equality index lookup — always qualifies.
        SqlPlan::DocumentIndexLookup {
            collection,
            field,
            value,
            ..
        } => Some(BitmapHint {
            collection: collection.clone(),
            field: field.clone(),
            primary_value: value.clone(),
            extra_values: Vec::new(),
        }),

        // Plain scan: inspect WHERE filters for indexed-column equality / IN-list.
        SqlPlan::Scan {
            collection,
            filters,
            ..
        } => {
            // The `SqlPlan::Scan` does not directly carry `IndexSpec` list — that
            // lives on `TableInfo` which the engine-rules layer consumed when it
            // chose *not* to rewrite to `DocumentIndexLookup`. However, when the
            // engine rules DID rewrite to `DocumentIndexLookup`, the caller should
            // match the first arm above.
            //
            // For plain `Scan` nodes we can still detect equality/in-list filters
            // but we have no way to confirm the column is indexed here — the planner
            // already had that information. We conservatively return `None` so we
            // never emit a sub-scan that would do a full table scan disguised as a
            // bitmap producer. Only the `DocumentIndexLookup` arm (already
            // index-backed) is emitted unconditionally.
            //
            // Future: if `Scan` carries index metadata, extend this arm.
            analyze_scan_filters(collection, filters)
        }

        _ => None,
    }
}

/// Attempt to extract an equality or bounded IN-list hint from scan filters.
///