| From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
|---|---|
| To: | Alessandro Gagliardi <alessandro(at)path(dot)com> |
| Cc: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: From Simple to Complex |
| Date: | 2012-02-02 14:52:17 |
| Message-ID: | CAHyXU0y5RaM6amFXnR-m=hQ0QmPsAA+Tw_erFe80JPY3_7iphQ@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On Wed, Feb 1, 2012 at 12:48 PM, Alessandro Gagliardi
<alessandro(at)path(dot)com> wrote:
> LIMIT 65536; Total query runtime: 14846 ms.
> - http://explain.depesz.com/s/I3E
> LIMIT 69632: Total query runtime: 80141 ms.
> - http://explain.depesz.com/s/9hp
>
> So it looks like when the limit crosses a certain threshold (somewhere north
> of 2^16), Postgres decides to do a Seq Scan instead of an Index Scan.
> I've already lowered random_page_cost to 2. Maybe I should lower it to 1.5?
> Actually 60K should be plenty for my purposes anyway.
also, is effective_cache_size set to a reasonable value?
merlin
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Gudmundur Johannesson | 2012-02-02 16:41:37 | Re: Index with all necessary columns - Postgres vs MSSQL |
| Previous Message | Merlin Moncure | 2012-02-01 19:35:35 | Re: Index with all necessary columns - Postgres vs MSSQL |