Need to speed up my UPDATE QUERY based on the EXPLAIN PLAN - sql

Question

I am updating my table data using a temporary table and it takes forever and it still has not completed. So I collected an explain plan on the query. Can someone advise me on how to tune the query or build indexes on them.
The query:
UPDATE w_product_d A
SET A.CREATED_ON_DT = (SELECT min(B.creation_date)
FROM mtl_system_items_b_temp B
WHERE to_char(B.inventory_item_id) = A.integration_id
and B.organization_id IN ('102'))
where A.CREATED_ON_DT is null;
Explain plan:
Plan hash value: 1520882583
-----------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------------
| 0 | UPDATE STATEMENT | | 47998 | 984K| 33M (2)|110:06:25 |
| 1 | UPDATE | W_PRODUCT_D | | | | |
|* 2 | TABLE ACCESS FULL | W_PRODUCT_D | 47998 | 984K| 9454 (1)| 00:01:54 |
| 3 | SORT AGGREGATE | | 1 | 35 | | |
|* 4 | TABLE ACCESS FULL| MTL_SYSTEM_ITEMS_B_TEMP | 1568 | 54880 | 688 (2)| 00:00:09 |
-----------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("A"."CREATED_ON_DT" IS NULL)
4 - filter("B"."ORGANIZATION_ID"=102 AND TO_CHAR("B"."INVENTORY_ITEM_ID")=:B1)
Note
-----
- dynamic sampling used for this statement (level=2)

Answer 1

For this query:
UPDATE w_product_d A
SET A.CREATED_ON_DT = (SELECT min(B.creation_date)
FROM mtl_system_items_b_temp B
WHERE to_char(B.inventory_item_id) = A.integration_id
and B.organization_id IN ('102'))
where A.CREATED_ON_DT is null;
You have a problem. Why are you creating a temporary table with the wrong type for inventory_item_id? That is likely to slow down any access. So, let's fix the table first and then do the update:
alter table mtl_system_items_b_temp
add better_inventory_item_id varchar2(255); -- or whatever the right type is
update mtl_system_items_b_temp
set better_inventory_item_id = to_char(inventory_item_id);
Next, let's define the appropriate index:
create index idx_mtl_system_items_b_temp_3 on mtl_system_items_b_temp(better_inventory_item_id, organization_id, creation_date);
Finally, an index on w_product_d can also help:
create index idx_ w_product_d_1 w_product_d(CREATED_ON_DT);
Then, write the query as:
UPDATE w_product_d p
SET CREATED_ON_DT = (SELECT min(t.creation_date)
FROM mtl_system_items_b_temp t
WHERE t.better_nventory_item_id) = p.integration_id and
t.organization_id IN ('102')
)
WHERE p.CREATED_ON_DT is null;

Answer 2

Try a MERGE statement. It will likely go faster because it can read all the mtl_system_items_b_temp records at once rather than reading them over-and-over again for each row in w_product_d.
Also, your tables look like they're part of an Oracle e-BS environment. In the MTL_SYSTEM_ITEMS_B in such an environment, the INVENTORY_ITEM_ID and ORGANIZATION_ID columns are NUMBER. You seem to be using VARCHAR2 in your tables. Whenever you don't use the correct data types in your queries, you invite performance problems because Oracle must implicitly convert to the correct data type and, in doing so, loses its ability to use indexes on the column. So, make sure your queries treat each column correctly according to it's datatype. (E.g., if a column is a NUMBER use COLUMN_X = 123 instead of COLUMN_X = '123'.
Here's the MERGE example:
MERGE INTO w_product_d t
USING ( SELECT to_char(inventory_item_id) inventory_item_id_char, min(creation_date) min_creation_date
FROM mtl_system_items_b_temp
WHERE organization_id IN ('102') -- change this to IN (102) if organization_id is a NUMBER field!
) u
ON ( t.integration_id = u.inventory_item_id_char AND t.created_on_dt IS NULL )
WHEN MATCHED THEN UPDATE SET t.created_on_dt = nvl(t.created_on_date, u.min_creation_date) -- NVL is just in case...