Re: 3 round trips over network for simply "select sysdate from dual"
Date: Fri, 20 Jun 2008 06:52:55 -0400
I am surprised it only takes 3.
Hard to say what OCI is doing in the background of SQL Plus my guess it is doing a 'describe' first then an 'execute' and 'fetch'. Which would account for the three round trips.
check out this link
which details the round trips that OCI uses, how one translates that into what SQLPlus implements is anyones guess.
I could just as well be doing a |OCIPing first or a ||OCISessionBegin for that matter.
The only way to find out is to talk to one of the Programmers who wrote
qihua wu wrote:
> Hi, all
> When using tcpdump to check what happen over the network when do a
> simple query as
> SQL> select sysdate from dual;
> 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
> 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