Re: DOCS: pg_plan_advice minor doc fixes - Mailing list pgsql-hackers

From jie wang
Subject Re: DOCS: pg_plan_advice minor doc fixes
Date
Msg-id CAJnZyeAdvzY01rTb_XDN3PfAPD0NZ61Ndf0J4j2H=GBTDVr5sQ@mail.gmail.com
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In response to DOCS: pg_plan_advice minor doc fixes  (Lakshmi N <lakshmin.jhs@gmail.com>)
Responses Re: DOCS: pg_plan_advice minor doc fixes
Re: DOCS: pg_plan_advice minor doc fixes
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Lakshmi N <lakshmin.jhs@gmail.com> 于2026年4月8日周三 15:09写道:
Hi hackers,

I noticed the following minor discrepancy in the pg_plan_advice docs, attached a patch to address this. 

(1) FOREIGN SCAN should be FOREIGN JOIN in the scan method advice tag. I tested with FOREIGN SCAN and can confirm it gives a syntax error while the other one works correctly.

postgres=# SET pg_plan_advice.advice = 'FOREIGN_JOIN((t1 t2))'; 
EXPLAIN (COSTS OFF, PLAN_ADVICE)
    SELECT * FROM fdw_t1 t1 JOIN fdw_t2 t2 ON t1.id = t2.t1_id;

SET
                   QUERY PLAN                    
-------------------------------------------------
 Foreign Scan
   Relations: (fdw_t1 t1) INNER JOIN (fdw_t2 t2)
 Supplied Plan Advice:
   FOREIGN_JOIN((t1 t2)) /* matched */
 Generated Plan Advice:
   FOREIGN_JOIN((t1 t2))
   NO_GATHER(t1 t2)
(7 rows)


(2) NESTED_LOOP_MEMOIZE is missing from the join method list in the doc though it is supported.  Verified this by running below:

postgres=# SET pg_plan_advice.advice = 'NESTED_LOOP_MEMOIZE(d)';
SET
postgres=# EXPLAIN (COSTS OFF, PLAN_ADVICE) select * from t1 f JOIN t2 ON f.id = t2.t1_id;
                 QUERY PLAN                
--------------------------------------------
 Hash Join
   Hash Cond: (t2.t1_id = f.id)
   ->  Seq Scan on t2
   ->  Hash
         ->  Seq Scan on t1 f
 Supplied Plan Advice:
   NESTED_LOOP_MEMOIZE(d) /* not matched */
 Generated Plan Advice:
   JOIN_ORDER(t2 f)
   HASH_JOIN(f)
   SEQ_SCAN(t2 f)
   NO_GATHER(f t2)
(12 rows)

Regards,
Lakshmi


Hi,

I found that this patch is not fully modified and is missing a part:
`Foreign Scan` --->  `Foreign Join`

Best regards,
--
wang jie 
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