PolarDB这个sql trace PLAN是NULL是什么原因呢？

* 7. row *
TYPE: SQL
SQL_ID: 5dd0natwyujq5
SCHEMA_NAME: echemi_db_v0_3
DIGEST_TEXT: SELECT sdt . produce_id , sdt . customer_id , sel . company_name AS company_name_m , sel . prefix_domain_name , sdt . products_id , sdt . products_url_name , SUBSTRING ( sdt . category_id , ?, ... ) AS category_id_lv1 , sdt . produce_cas_no AS cas_no , sdt . produce_name , sdt . produce_url_name , sdt . goods_picture_s , sdt . goods_picture_m AS goods_picture , sdt . goods_picture_b , sdt . complete_flag , sdt . hot_flag , sdt . main_flag , sdt . grade_name , sdt . content , sdt . package_name , sdt . n_price_type , sdt . n_price_trade_term_type , sdt . n_price_trade_term_text , sdt . n_price , sdt . n_price_unit , sdt . n_price_currency , sdt . n_price_currency_symbol , CASE WHEN CEILING ( IFNULL ( sdt . n_min_price , ? ) ) = ? THEN ? WHEN sdt . n_price_end_date < CURDATE ( ) THEN ? ELSE ? END AS n_pending_flag , sdt . activity_id , sdt . activity_type , sdt . a_price_trade_term_type , sdt . a_price_trade_term_text , sdt . a_price , sdt . a_price_unit , sdt . a_price_currency , sdt . a_price_currency_symbol FROM t_e_all_produce_v1 sdt INNER JOIN t_e_all_seller_v1 sel ON sdt . customer_id = sel . customer_id WHERE sdt . delflag = ? AND sel . delflag = ? AND sdt . customer_id = ? AND sdt . products_id = ? AND sdt . produce_id != ? AND sdt . complete_flag = ? ORDER BY sdt . produce_update_date DESC LIMIT ?
PLAN_ID: NULL
PLAN: NULL
PLAN_EXTRA: NULL
ERROR_CODE: NULL
REF_BY: ["SQL_TRACE"]
FIRST_LOAD_TIME: 2024-04-17 13:24:13
LAST_HIT_TIME: 2024-04-29 14:42:42
EXECUTIONS: 213841
SUM_WAIT_TIME: 47130387
MIN_WAIT_TIME: 156
MAX_WAIT_TIME: 12521
SUM_EXEC_TIME: 0
MIN_EXEC_TIME: 0
MAX_EXEC_TIME: 0
SUM_ROWS_SENT: 125249
MIN_ROWS_SENT: 0
MAX_ROWS_SENT: 6
SUM_ROWS_EXAMINED: 24990973
MIN_ROWS_EXAMINED: 0
MAX_ROWS_EXAMINED: 98182
SUM_ROWS_AFFECTED: 0
MIN_ROWS_AFFECTED: 0
MAX_ROWS_AFFECTED: 0
SUM_LOGICAL_READ: 0
MIN_LOGICAL_READ: 0
MAX_LOGICAL_READ: 0
SUM_PHY_SYNC_READ: 0
MIN_PHY_SYNC_READ: 0
MAX_PHY_SYNC_READ: 0
SUM_PHY_ASYNC_READ: 0
MIN_PHY_ASYNC_READ: 0
MAX_PHY_ASYNC_READ: 0
EXTRA: NULL PolarDB这个sql trace PLAN是NULL是什么原因呢？