It seems it has to do a loop on 14 billion rows? Can someone explain why this would happen?
Thanks,
Teddy
From: Teddy Schmitz Sent: Thursday, February 16, 2017 12:32:41 PM To: pgsql-general@postgresql.org Subject: Problems with Greatest
Hello,
I have a query using Greatest that hangs and never returns when called with two tables.
Postgres Version: 9.6
Tables
t1{ id bigint }
t2 { id bigint }
they are sharing a sequence
the query
select greatest(max(t1.id), max(t2.id)) from t1, t2;
The purpose was to call setval on the sequence after doing a bulk data load into the database. But this query never returns. I have tried it with various combinations,
select greatest(max(t1.id), 6) from t1; -> This returns select greatest(max(t1.id), 6) from t1, t2; -> This never returns.
The query does work if there is only a few hundred items between the tables but I'm importing about ~300,000 rows between the two tables. I looked at pg_stat_activity and it says the query is active
I worked around this problem using a union all query but I'm wondering if this is a bug or I am just using greatest wrong.
