diff --git a/backend/spi/spi-search/src/serv/pg/search_pg_item_serv.rs b/backend/spi/spi-search/src/serv/pg/search_pg_item_serv.rs
index c81decff5..86e2bbc2e 100644
--- a/backend/spi/spi-search/src/serv/pg/search_pg_item_serv.rs
+++ b/backend/spi/spi-search/src/serv/pg/search_pg_item_serv.rs
@@ -461,7 +461,7 @@ pub async fn search(search_req: &mut SearchItemSearchReq, funs: &TardisFunsInst,
                 ));
             } else if ext_item.op == BasicQueryOpKind::Len {
                 if let Some(first_value) = value.pop() {
-                    where_fragments.push(format!("(length(ext->>'{}')={})", ext_item.field, sql_vals.len() + 1));
+                    where_fragments.push(format!("(length(ext->>'{}') = ${})", ext_item.field, sql_vals.len() + 1));
                     sql_vals.push(first_value);
                 } else {
                     return err_not_found(ext_item);