diff --git a/fixtures/merger.json b/fixtures/merger.json
index 3608978..3688345 100644
--- a/fixtures/merger.json
+++ b/fixtures/merger.json
@@ -1461,17 +1461,7 @@
           "success": true,
           "sql": [
             [
-              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*) || to_jsonb(t3.*) || to_jsonb(t4.*)",
-              "FROM agreego.\"entity\" t1",
-              "JOIN agreego.\"organization\" t2 ON ",
-              "JOIN agreego.\"user\" t3 ON ",
-              "JOIN agreego.\"person\" t4 ON ",
-              "WHERE",
-              "  t1.id = '{{uuid:data.id}}'",
-              "  OR (\"first_name\" = 'LookupFirst'",
-              "  AND \"last_name\" = 'LookupLast'",
-              "  AND \"date_of_birth\" = '{{timestamp}}'",
-              "  AND \"pronouns\" = 'they/them'))"
+              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*) || to_jsonb(t3.*) || to_jsonb(t4.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"organization\" t2 ON t2.id = t1.id LEFT JOIN agreego.\"user\" t3 ON t3.id = t1.id LEFT JOIN agreego.\"person\" t4 ON t4.id = t1.id WHERE t1.id = '{{uuid:data.id}}' UNION SELECT to_jsonb(t1.*) || to_jsonb(t2.*) || to_jsonb(t3.*) || to_jsonb(t4.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"organization\" t2 ON t2.id = t1.id LEFT JOIN agreego.\"user\" t3 ON t3.id = t1.id LEFT JOIN agreego.\"person\" t4 ON t4.id = t1.id WHERE (\"first_name\" = 'LookupFirst' AND \"last_name\" = 'LookupLast' AND \"date_of_birth\" = '{{timestamp}}' AND \"pronouns\" = 'they/them'))"
             ],
             [
               "INSERT INTO agreego.\"entity\" (",
@@ -1614,17 +1604,7 @@
           "success": true,
           "sql": [
             [
-              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*) || to_jsonb(t3.*) || to_jsonb(t4.*)",
-              "FROM agreego.\"entity\" t1",
-              "JOIN agreego.\"organization\" t2 ON ",
-              "JOIN agreego.\"user\" t3 ON ",
-              "JOIN agreego.\"person\" t4 ON ",
-              "WHERE",
-              "  t1.id = '{{uuid:data.id}}'",
-              "  OR (\"first_name\" = 'LookupFirst'",
-              "  AND \"last_name\" = 'LookupLast'",
-              "  AND \"date_of_birth\" = '{{timestamp}}'",
-              "  AND \"pronouns\" = 'they/them'))"
+              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*) || to_jsonb(t3.*) || to_jsonb(t4.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"organization\" t2 ON t2.id = t1.id LEFT JOIN agreego.\"user\" t3 ON t3.id = t1.id LEFT JOIN agreego.\"person\" t4 ON t4.id = t1.id WHERE t1.id = '{{uuid:data.id}}' UNION SELECT to_jsonb(t1.*) || to_jsonb(t2.*) || to_jsonb(t3.*) || to_jsonb(t4.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"organization\" t2 ON t2.id = t1.id LEFT JOIN agreego.\"user\" t3 ON t3.id = t1.id LEFT JOIN agreego.\"person\" t4 ON t4.id = t1.id WHERE (\"first_name\" = 'LookupFirst' AND \"last_name\" = 'LookupLast' AND \"date_of_birth\" = '{{timestamp}}' AND \"pronouns\" = 'they/them'))"
             ],
             [
               "INSERT INTO agreego.\"entity\" (",
@@ -2219,12 +2199,7 @@
           "success": true,
           "sql": [
             [
-              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*)",
-              "FROM agreego.\"entity\" t1",
-              "JOIN agreego.\"order\" t2 ON ",
-              "WHERE",
-              "  t1.id = 'abc'",
-              "  OR (\"id\" = 'abc'))"
+              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"order\" t2 ON t2.id = t1.id WHERE t1.id = 'abc' UNION SELECT to_jsonb(t1.*) || to_jsonb(t2.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"order\" t2 ON t2.id = t1.id WHERE (\"id\" = 'abc'))"
             ],
             [
               "INSERT INTO agreego.\"entity\" (",
@@ -3499,12 +3474,7 @@
           "success": true,
           "sql": [
             [
-              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*)",
-              "FROM agreego.\"entity\" t1",
-              "JOIN agreego.\"invoice\" t2 ON ",
-              "WHERE",
-              "  t1.id = '{{uuid:data.id}}'",
-              "  OR (\"id\" = '{{uuid:data.id}}'))"
+              "(SELECT to_jsonb(t1.*) || to_jsonb(t2.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"invoice\" t2 ON t2.id = t1.id WHERE t1.id = '{{uuid:data.id}}' UNION SELECT to_jsonb(t1.*) || to_jsonb(t2.*) FROM agreego.\"entity\" t1 LEFT JOIN agreego.\"invoice\" t2 ON t2.id = t1.id WHERE (\"id\" = '{{uuid:data.id}}'))"
             ],
             [
               "INSERT INTO agreego.\"entity\" (",
diff --git a/src/merger/mod.rs b/src/merger/mod.rs
index ce5fcb2..0159fea 100644
--- a/src/merger/mod.rs
+++ b/src/merger/mod.rs
@@ -744,9 +744,19 @@ impl Merger {
       return Ok(None);
     }
 
-    let where_clause = format!("WHERE {}", where_parts.join(" OR "));
-
-    let final_sql = format!("{} {}", fetch_sql_template, where_clause);
+    // An OR across the hierarchy join is un-indexable — it forces a full scan
+    // of the subtype table on every child merge. UNION lets each arm use its
+    // own index (pk for the id arm, the lk_ unique index for the lookup arm)
+    // and still dedups, so TOO_MANY_LOOKUP_ROWS semantics are preserved.
+    let final_sql = if where_parts.len() == 1 {
+      format!("{} WHERE {}", fetch_sql_template, where_parts[0])
+    } else {
+      where_parts
+        .iter()
+        .map(|p| format!("{} WHERE {}", fetch_sql_template, p))
+        .collect::<Vec<_>>()
+        .join(" UNION ")
+    };
 
     let fetched = match self.db.query(&final_sql, None) {
       Ok(Value::Array(table)) => {