diff --git a/modules/fundamental/src/license/service/mod.rs b/modules/fundamental/src/license/service/mod.rs
index b44a3d742..63e7174ba 100644
--- a/modules/fundamental/src/license/service/mod.rs
+++ b/modules/fundamental/src/license/service/mod.rs
@@ -297,22 +297,29 @@ impl LicenseService {
             .distinct()
             .column_as(expanded_license::Column::ExpandedText, LICENSE_TEXT);
 
-        // Build query for non-expanded licenses: includes both
+        // Build query for licenses not yet linked to any SBOM: includes both
         //   (a) pre-loaded SPDX dictionary entries with no SBOM connection yet, AND
-        //   (b) CycloneDX licenses that exist in sbom_package_license but were never expanded.
-        // A LEFT JOIN on sbom_package_license (instead of INNER JOIN) ensures pre-loaded licenses
-        // with no SBOM attachment are included. Then filtering for sbom_license_expanded IS NULL
-        // removes SPDX licenses that have already been expanded (they appear in spdx_query instead).
+        //   (b) licenses from older SBOMs ingested before license expansion was implemented.
+        // Use NOT EXISTS instead of LEFT JOIN + IS NULL to find licenses without SBOMs.
+        // On large tables, LEFT JOIN scans all rows while NOT EXISTS
+        // uses a Nested Loop Anti Join with index-only scan.
+        let exists_subquery = sea_query::Query::select()
+            .expr(Expr::val(1))
+            .from(sbom_license_expanded::Entity)
+            .and_where(
+                Expr::col((
+                    sbom_license_expanded::Entity,
+                    sbom_license_expanded::Column::LicenseId,
+                ))
+                .equals((license::Entity, license::Column::Id)),
+            )
+            .to_owned();
+
         let mut non_sbom_query = license::Entity::find()
             .select_only()
             .distinct()
             .column_as(license::Column::Text, LICENSE_TEXT)
-            .join(JoinType::LeftJoin, license::Relation::PackageLicense.def())
-            .join(
-                JoinType::LeftJoin,
-                sbom_license_expanded::Relation::License.def().rev(),
-            )
-            .filter(sbom_license_expanded::Column::LicenseId.is_null());
+            .filter(Expr::exists(exists_subquery).not());
 
         // Apply filtering to both queries (without sorting - that's applied to the UNION result)
         let filter_only = Query {
diff --git a/modules/ingestor/src/graph/sbom/common/expanded_license.rs b/modules/ingestor/src/graph/sbom/common/expanded_license.rs
index 6fb55765a..341e74fe2 100644
--- a/modules/ingestor/src/graph/sbom/common/expanded_license.rs
+++ b/modules/ingestor/src/graph/sbom/common/expanded_license.rs
@@ -16,6 +16,18 @@ use uuid::Uuid;
 ///
 /// While SeaORM could express this via custom expressions, it would be significantly
 /// more verbose and harder to maintain than the raw SQL.
+///
+/// # Differences from Migration Backfill
+///
+/// The migration in m0002120_normalize_expanded_license/up.sql performs a similar
+/// operation but with key differences:
+/// - Migration: Pre-deduplicates by (text, sbom_id) and uses WHERE NOT EXISTS to skip
+///   already-backfilled SBOMs. Optimized for one-time bulk processing.
+/// - Ingestion: Filters by specific sbom_id parameter for single-SBOM processing.
+///   Uses ON CONFLICT for idempotent re-ingestion of the same SBOM.
+///
+/// Both use the same core logic (expand_license_expression_with_mappings + md5 hash
+/// matching) but optimize for their different use cases.
 pub async fn populate_expanded_license(
     sbom_id: Uuid,
     db: &impl ConnectionTrait,
diff --git a/modules/ingestor/src/graph/sbom/cyclonedx.rs b/modules/ingestor/src/graph/sbom/cyclonedx.rs
index 5ae3a824e..fe0019d69 100644
--- a/modules/ingestor/src/graph/sbom/cyclonedx.rs
+++ b/modules/ingestor/src/graph/sbom/cyclonedx.rs
@@ -138,11 +138,11 @@ impl<'a> From<Information<'a>> for SbomInformation {
 
 impl SbomContext {
     #[instrument(skip(connection, sbom, warnings), err(level=tracing::Level::INFO))]
-    pub async fn ingest_cyclonedx<C: ConnectionTrait>(
+    pub async fn ingest_cyclonedx(
         &self,
         mut sbom: Box<CycloneDx>,
         warnings: &dyn ReportSink,
-        connection: &C,
+        connection: &impl ConnectionTrait,
     ) -> Result<(), Error> {
         // pre-flight checks
 
diff --git a/modules/ingestor/src/graph/sbom/spdx.rs b/modules/ingestor/src/graph/sbom/spdx.rs
index 2a1e564d5..53d6e65da 100644
--- a/modules/ingestor/src/graph/sbom/spdx.rs
+++ b/modules/ingestor/src/graph/sbom/spdx.rs
@@ -103,11 +103,11 @@ impl<'a> From<Information<'a>> for SbomInformation {
 
 impl SbomContext {
     #[instrument(skip(db, sbom_data, warnings), ret(level=tracing::Level::DEBUG))]
-    pub async fn ingest_spdx<C: ConnectionTrait>(
+    pub async fn ingest_spdx(
         &self,
         sbom_data: SPDX,
         warnings: &dyn ReportSink,
-        db: &C,
+        db: &impl ConnectionTrait,
     ) -> Result<(), Error> {
         // pre-flight checks