I am running a background task on my DB, which will copy data from tableA to tableB. For that, I'm writing a PL/PGSQL function which basically needs to do the following:
Select the data from tableA
The limit will be put when calling the function
insert the selected data on Step 1 onto new table
Question:
When I stop it and start it again, how can the query "know" that it has already processed some rows so it won't do it twice on the same rows? If it stopped on row number 100, I need it to continue on row number 101, for example.
How can I ask the function to return the number of processed rows?
I can add a column on TableB if needed, but not on tableA.
This is what I've done so far:
select data_copy(500);
CREATE or REPLACE FUNCTION data_copy(rows integer)
RETURNS SETOF bigint AS $$
declare
row record;
offset_num integer;
BEGIN
FOR row IN EXECUTE '
SELECT
id,
path,
name,
name_last,
created_at
FROM
tablea
WHERE
ready = true
ORDER BY 1 LIMIT ' || rows || ' OFFSET ' || rows || ''
LOOP
INSERT INTO tableB (id,path,name,name_last,created_at)