| From: | Thomas Kellerer <spam_eater(at)gmx(dot)net> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Problems with Greatest |
| Date: | 2017-02-16 07:10:25 |
| Message-ID: | o83j8r$31t$1@blaine.gmane.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
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
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Alessandro Baggi | 2017-02-16 08:11:54 | Re: postgresql how to duplicate rows in result. |
| Previous Message | Teddy Schmitz | 2017-02-16 04:45:49 | Re: Problems with Greatest |