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BIND_AWARE hint not working in cursors from PL/SQL functions

bschneidAug 1 2013 — edited Aug 3 2013

I am using Oracle 11.2.0.3.0, Enterprise Edition

BIND_AWARE hint is not applied to cursors declared in PL/SQL functions.  It DOES work in procedures.

Example below - the only difference is one is a procedure, and one is a function.  When cursors are created, the one created from within the procedure gets V$SQL.IS_BIND_AWARE = 'Y' immediately, while the one created from within the function is 'N'.

How do I fix that?

CREATE OR REPLACE PROCEDURE PROC_BIND_TEST(v_region_id number) as

cursor

  c1 is select /*+ bind_aware */ /*+ proc_bind_test */ count(1)

  from sales where region_id = v_region_id

  begin

  for row in c1 loop

  null;

  end loop;

end;

/

CREATE OR REPLACE FUNCTION FUNCTION_BIND_TEST(v_region_id number)

return number

as

cursor

  c1 is select /*+ bind_aware */ /*+ function_bind_test */ count(1)

  from sales where region_id = v_region_id

begin

  for row in c1 loop

  null;

  end loop;

  return 0;

end;

/

exec proc_bind_test(12345);

select /*+ bind_aware */ function_bind_test(12345) from dual;

SELECT first_load_time , SQL_ID, CHILD_NUMBER, IS_BIND_AWARE, SQL_FULLTEXT

FROM V$SQL

where sql_text like '%bind_test%'

order by FIRST_LOAD_TIME desc;

Comments

mariam.kupa

Hello,

I have seen the same problem when using fast refresh materialized view that uses mview log also.

Do an explicit  select privilege for the mlog:

grant select on mlog$_<master_table> to <mview_schema>

https://deeparaja.wordpress.com/2012/07/17/materialized-view-fast-refresh-fails-with-ora-12018-ora-00942/

Martin Preiss

thank you for the answer and the link: but in my case the owner of table and mview is the same and the ora-942 is not related to the accessed table, but to an internal object and furthermore a transient object, that cannot be found in the dictionary at all (so the ora-942 makes sense - but not the idea to gather statistics for this object at all).

BobLilly

Hi Martin,

Have you tried the OPT_PARAM('optimizer_dynamic_sampling', '0') hint?

Regards,

Bob

AndrewSayer
Answer

I can replicate on my 12.2 instance, it looks like there's a problem with the lateral view existing in the execution plan. I can't see a no lateral view hint, and I couldn't see anything in the plan outline that looks relevant but you can hint to use an older optimizer environment, 11.1.0.7 did the trick for me (although it was the first I chose).

create materialized view t_mv

as

select /*+OPTIMIZER_FEATURES_ENABLE('11.1.0.7')*/t.col1, t.col2, r.val

  from t,

  LATERAL (SELECT MIN(val) AS val

            FROM JSON_TABLE ( t.col2, '$[*].target'

                              COLUMNS (val NUMBER PATH '$')

                              )

          ) r;

exec dbms_mview.refresh('t_mv','c')

PL/SQL procedure successfully completed.

I suggest you raise an SR as this could effect a lot of other things, and should be relatively painless as you've got an easily reproducible test case

Marked as Answer by Martin Preiss · Sep 27 2020
Donatello Settembrino

trying on a 12.2 with SYS user (disabling query rewrite) it seems to work correctly without modifying OFE

SQL> select user from dual;

USER

------

SYS

SQL> create materialized view t_mv

  2  disable query rewrite

  3  as

  4  select t.col1, t.col2, r.val

  5    from t,

  6    LATERAL (SELECT MIN(val) AS val

  7              FROM JSON_TABLE ( t.col2, '$[*].target'

  8                                COLUMNS (val NUMBER PATH '$')

  9                                )

10            ) r;

Creata vista materializzata.

SQL> exec dbms_mview.refresh('T_MV');

Procedura PL/SQL completata correttamente.

Mustafa KALAYCI

Hi Martin,

I have the same result but if you change the query as a subquery it works. of course mv does not support scalar subqueries so I created a view to achive that:

create or replace view v_x as

select t.col1, t.col2, (SELECT min(val) AS val

                         FROM JSON_TABLE ( t.col2, '$[*].target'

                                           COLUMNS (val NUMBER PATH '$')

                                          )

                       ) as val

from t;

drop materialized view t_mv;

create materialized view t_mv

as

select * from v_x;

exec dbms_mview.refresh('t_mv');

it works and when I checked the execution plan of the view I can see that VW_LAT*** view. I hope that gives some idea.

Martin Preiss

Hi Andrew,

thank you for the hint: I didn't consider this option since the lateral join was a 12c addition (if I recall  this right). This should work in the given context.

Regards

Martin

Martin Preiss

Hi Donatello,

SYS is special: I would not be surprised to see different strategies, when SYS is concerned.

Regards

Martin

Martin Preiss

Hi Mustafa,

thank you for adding this solution, which would also be a valid option.

Regards

Martin

Donatello Settembrino

in fact, I did not indicate it as a solution but it seemed "strange" to me that without changing the behavior of the optimizer (OFE) it would still work under SYS user.

Regards

Martin Preiss

strange indeed, but SYS tends to include strange effects.

AndrewSayer

Dom Brooks wrote:

Would be interesting to know what fix is responsible

https://blog.dbi-services.com/ofe-optimizer-features-enable/

https://blog.tanelpoder.com/posts/scripts-for-drilling-down-into-unknown-optimizer-changes/

I tried the obvious parameter (with lateral in the name) but it wasn't that. I started writing some scripts a while ago to brute force these things with explain plan, but only managed to get as far as it cycling through fix controls (and can confirm there's no fix control in it). Mauro Pagano's Pathfinder (which my scripts mimic) does include hidden parameters but it has to execute the SQL each time and needs to be run as SYS (which doesn't seem to have the problem) https://mauro-pagano.com/category/pathfinder/ . Might be worth kicking off overnight and checking the results in the morning.

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Locked on Aug 31 2013
Added on Aug 1 2013
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