I've created a function that allows me to do an huge update.
But I need to limit this function. I need to do 50k rows (example) and then stop it. After that I need to continue from the rows that I've stopped... I'll have to modify the call function select batch_number() as well.
How can I do that? Using for?
It is customary to restrict emails to a single list or at least make others aware when you do have a legitmate need to cross-post.
Specifically your post on -admin <“Break” in plpgsql Function - PostgreSQL 9.2>
Yes, it didn't belong on -admin in the first place but posting it here with a different title and not indicating on either thread that the other exists and/or is the valid one just makes it harder for others to follow along.
As for your general question I try to approach this problem in the following manner:
SELECT however many of something that you need (FOR UPDATE)
UPDATE those selected to indicate that they have been seen
PROCESS them as needed
repeat step 1 until it returns no records
It doesn't always work - and given a sufficiently large number of records it may be unadvisable - but it is set-oriented which is generally a plus in SQL.
The other way to assign batches is to use the integer modulus operator (e.g., 10 % 3 = 1 : read 3 remainder of 1) or integer division (10 / 3 = 3) to derive the batch number based upon an attribute of the data itself as opposed to its order of appearance in a result set.
David J.
