update NULL values of left joint table in Postgres

Question

I have these two tables in my database document and location.

select * from  Document     

id  locid   loccode
1   1010    30
2   2020    30
3   3030    30
4   4040    40

select * from location

locid   loccode date    Status
1010    30  20-10-2019  A
2020    30  20-10-2019  A
3030    40  20-10-2019  A
4040    40  20-10-2019  A
6060    30  20-10-2019  A
7070    40  20-10-2019  A
8080    30  20-10-2019  D
9090    40  20-10-2019  D

i want to update status in location table whose record (left join null values) not available Document. i try below query but it taking more time.

update location 
set status='D' 
from location A 
left join document B on A.locid=B.locid and A.loccode=B.loccode  
where b.id is NULL;

Please help me how to fix it

Answer 1

I would recommend not exists :

update location 
set status = 'D' 
where not exists (
    select 1 
    from document d
    where d.locid = location.locid and d.loccode = location.loccode
)

For performance, you want an index on document(locid, loccode) , so the subquery executes fast. An index on location(locid, loccode) might also help.