How to send array parameter to remote over dblink in oracle - oracle

Question

I have several instances: dbA, dbB, dbC.., then i want to query data from local and link to other instance over dblink, and expected is l_ids will be send to remote site cause l_ids is ligh and table#dbA is numerous, just as followering:
DECLARE
out_row_data SYS_REFCURSOR;
l_ids UDT_TBL_NUMBER; -- TABLE OF NUMBER(10)
l_sql VARCHAR2(18000);
BEGIN
l_sql := 'SELECT * FROM tableX#dbA
WHERE column IN (SELECT * FROM TABLE(:l_ids));'
OPEN out_row_data FOR l_sql
USING l_ids;
END;/
But execution plan shows data of tableX fetched first, then join with table(l_ids).
Another try, using driving_site hint to specify it, but didn't work either:
DECLARE
out_row_data SYS_REFCURSOR;
l_ids UDT_TBL_NUMBER; -- TABLE OF NUMBER(10)
l_sql VARCHAR2(18000);
BEGIN
l_sql := 'SELECT /*+ MONITOR driving_site(X) */ * FROM TABLE(:l_ids) GIDS
LEFT JOIN tableX#dbA X ON GIDS.column_value = X.column;'
OPEN out_row_data FOR l_sql
USING l_ids;
END;/
I have no idea now, above statement all process successfully, but execution plan aren't as expected.
Can someone help me or need more info? :(
Update
I think if driving_site is work, the tableX REMOTE operation shouldn't exist.
Streamline dynamic sqltext:
l_sql := '
WITH matched_Y AS (
SELECT *
FROM tableY#dbB
), matched_X AS (
SELECT /*+ MONITOR no_merge(X) */
column1
,sum(column2)
FROM
(
SELECT /*+ MONITOR driving_site(RX) DRSITE */ * FROM
TABLE(:ids) GIDS
LEFT JOIN tableX#dbA RX
ON GIDS.column_value = RX.column1
) X
LEFT JOIN TABLE(:currency_table) ct
ON column3 >= ct.column3
GROUP BY column1
), matched_X2 AS (
SELECT *
FROM (matched_X)
GROUP BY column1
)
SELECT *
FROM matched_Y g
LEFT JOIN matched_X2 w ON g.column1 = w.column1
ORDER BY g.column4 DESC';
Execution plan
**---------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | Inst |IN-OUT|
---------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | | 3141 (100)| | | |
| 1 | SORT ORDER BY | | 11790 | 9936K| 10M| 3141 (1)| 00:00:01 | | |
|* 2 | HASH JOIN RIGHT OUTER | | 11790 | 9936K| | 1001 (1)| 00:00:01 | | |
| 3 | VIEW | | 1 | 130 | | 60 (2)| 00:00:01 | | |
| 4 | HASH GROUP BY | | 1 | 96 | | 60 (2)| 00:00:01 | | |
| 5 | NESTED LOOPS OUTER | | 20 | 1920 | | 59 (0)| 00:00:01 | | |
| 6 | VIEW | | 1 | 94 | | 30 (0)| 00:00:01 | | |
|* 7 | FILTER | | | | | | | | |
|* 8 | HASH JOIN | | 1 | 109 | | 30 (0)| 00:00:01 | | |
| 9 | REMOTE | tableX| 1 | 107 | | 1 (0)| 00:00:01 | DBLIN~ | R->S |
| 10 | COLLECTION ITERATOR PICKLER FETCH| | 100 | 200 | | 29 (0)| 00:00:01 | | |
|* 11 | COLLECTION ITERATOR PICKLER FETCH | | 20 | 40 | | 29 (0)| 00:00:01 | | |
|* 12 | VIEW | | 11790 | 8439K| | 941 (1)| 00:00:01 | | |
| 13 | REMOTE | | | | | | | DBLIN~ | R->S |
---------------------------------------------------------------------------------------------------------------------------**

Answer 1

In a true distributed query, the optimization is done on the sending site. Because your local site may not have access to the CBO statistics on the remote site.
The driving_site hint forces query execution to be done at a different site than the initiating instance. This is done when the remote table is much larger than the local table and you want the work (join, sorting) done remotely to save the back-and-forth network traffic.
Your plan is behaving correctly, from the perspective of the driving site, and without proper knowledge of the filter operations done by the optimizer ( this part of the plan is not in your post ), I would suggest to try and get rid of the nested loops outer produced by the left join, to see whether a hash join can behave better.
WITH matched_Y AS (
SELECT /*+ materialize */ *
FROM tableY#dbB
), matched_X AS (
SELECT /*+ MONITOR no_merge(X) use_hash(ct,x) */
column1
,sum(column2)
FROM
(
SELECT /*+ MONITOR driving_site(RX) DRSITE */ * FROM
TABLE(:ids) GIDS
LEFT JOIN tableX#dbA RX
ON GIDS.column_value = RX.column1
) X
LEFT JOIN TABLE(:currency_table) ct
ON column3 >= ct.column3
GROUP BY column1
), matched_X2 AS (
SELECT *
FROM (matched_X)
GROUP BY column1
)
SELECT *
FROM matched_Y g
LEFT JOIN matched_X2 w ON g.column1 = w.column1
ORDER BY g.column4 DESC