How do I delete a fixed number of rows with sorting in PostgreSQL?

Question

I\'m trying to port some old MySQL queries to PostgreSQL, but I\'m having trouble with this one:

DELETE FROM logtable ORDER BY timestamp LIMIT 10;
         


        

Answer 1

Assuming you want to delete ANY 10 records (without the ordering) you could do this:

DELETE FROM logtable as t1 WHERE t1.ctid < (select t2.ctid from logtable as t2  where (Select count(*) from logtable t3  where t3.ctid < t2.ctid ) = 10 LIMIT 1);

For my use case, deleting 10M records, this turned out to be faster.