Teddy Schmitz schrieb am 16.02.2017 um 05:38:
> As a quick follow up I just did an explain on the query,
>
>
> Aggregate (cost=258007258.87..258007258.88 rows=1 width=8)
> -> Nested Loop (cost=0.00..184292254.83 rows=14743000807 width=16)
> -> Seq Scan on t1 (cost=0.00..3796.41 rows=263141 width=8)
> -> Materialize (cost=0.00..1088.40 rows=56027 width=8)
> -> Seq Scan on t2 (cost=0.00..808.27 rows=56027 width=8)
>
>
> It seems it has to do a loop on 14 billion rows? Can someone explain why this would happen?
You are not joining those two tables.
"from t1, t2" is a cross join that will calculate the cartesian product of both tables
