UPDATE with table join

[Tarlika Elisabeth Schmitz <postgresql(at)numerixtechnology(dot)de>]

I need to update some records in a table depending on values in another
table:

UPDATE 
 item SET export_time = now()
WHERE item_pk IN 
(
 SELECT
  item.item_pk AS pk
 FROM ITEM
 LEFT JOIN product product ON Item.product_fk = product.product_pk 
 WHERE product.xyz = 't' AND ...
)


Is this the most efficient way of doing this?
Is there a limit to the number of results that IN can cope with?

This needs to run on Postgres 7.4.

--


Best Regards,

Tarlika Elisabeth Schmitz


A: Because it breaks the logical sequence of discussion
Q: Why is top posting bad?