Re: 3 round trips over network for simply "select sysdate from dual"

I used tcpdum tool on windows
run the command
tcpdump host databaseserver

On Fri, Jun 20, 2008 at 5:29 PM, Desai, Bhavik (MLITS) <Bhavik_Desai_at_ml.com> wrote:

> *Hi,*
>
> * *
>
> *Can I request you to show how did you take tcpdump for a query ?*
>
> * *
>
> -----Original Message-----
> *From:* oracle-l-bounce_at_freelists.org [mailto:
> oracle-l-bounce_at_freelists.org] *On Behalf Of *qihua wu
> *Sent:* Friday, June 20, 2008 2:44 PM
> *To:* oracle-l
> *Subject:* 3 round trips over network for simply "select sysdate from
> dual"
>
>
>
> Hi, all
>
> When using tcpdump to check what happen over the network when do a simple
> query as
> SQL> select sysdate from dual;
>
> SYSDATE
> ---------
> 20-JUN-08
>
> The tcpdump is as following, 3 round trips between the server and client.
> Why so many trips? Don't we only need to 1 round trip as client send the
> query and the server reply?
>
> 16:56:13.354672 IP host1 > host2.1580: . 7898:8 054(156) ack 6755 win 32768
> 16:56:13.354683 IP host2.1580 > host1: . 6755:6 836(81) ack 8054 win 32768
> 16:56:13.521731 IP host1 > host2.1580: . 8054:8 126(72) ack 6836 win 32768
> 16:56:13.521744 IP host2.1580 > host1: . 6836:6 853(17) ack 8126 win 32768
> 16:56:13.688967 IP host1 > host2.1580: . 8126:8 141(15) ack 6853 win 32768
> 16:56:13.688980 IP host2.1580 > host1: . 6853:6 874(21) ack 8141 win 32768
>
>
> And the expert says below: one additional roundtrip to initiate the query.
> Don't quite understand why we need additional roundtrip to initiate.
> http://www.adp-gmbh.ch/ora/sqlplus/arraysize.html
>
> Thanks,
> Qihua
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