Re: Hash Aggregate plan picked for very large table == out of memory

Thanks Tom. Here's more info:

What have you got work_mem set to?  

40960

What's the actual number of groups
(target_page_id values)?

Approximately 40 million (I'll have a more precise number when the query finishes running ).

Maybe this helps?

crystal=> select null_frac, n_distinct, correlation from pg_stats where tablename = 'page_page_link' and attname = 'target_page_id';
 null_frac | n_distinct | correlation
-----------+------------+-------------
         0 |     550017 |    0.240603
(1 row)

Mason