fix #565: read ORDS vector body stream once

sql/adb/29_agent_ords_vector_search_ords.sql

@@ -48,19 +48,24 @@ BEGIN
     p_source         => q'!
 DECLARE
   v_rows           SYS_REFCURSOR;
+  v_body_text      CLOB;
   v_embedding_text VARCHAR2(32767);
 BEGIN
   cb_ords_handler_pkg.set_vpd_context(:auth_header);
 
+  -- ORDS exposes :body_text as a stream bind. Read it exactly once; referring
+  -- to the stream bind twice causes ORA-17270 (Duplicate stream parameter).
+  v_body_text := :body_text;
+
   -- JSON_QUERY accepts a numeric JSON array. The JSON_VALUE fallback also
   -- permits clients that send the vector as the text "[0.1,0.2,...]".
   v_embedding_text := JSON_QUERY(
-    :body_text,
+    v_body_text,
     '$.embedding' RETURNING VARCHAR2(32767)
   );
   IF v_embedding_text IS NULL THEN
     v_embedding_text := JSON_VALUE(
-      :body_text,
+      v_body_text,
       '$.embedding' RETURNING VARCHAR2(32767)
     );
   END IF;