Re: Does oracle db serialize concurrent read-only SELECT ?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 18 Apr 2001 21:32:50 +0100
Message-ID: <987625751.16418.0.nnrp-12.9e984b29@news.demon.co.uk>

The 1,504 waits to and from clients make it look as if you have an arraysize of 1 in your client and have about 1,500 rows in the query - I thought you had said that you had changed this to 1,000.

Most of the time waited by this session the 3.93 seconds waiting for each row to be acknowledged by the client and the next to be requested by the client. The problem isn't at the database end of the system, it seems to be occurring at the client end of the system, or perhaps in the network layer between the server and the client.

There is some room for error here, as Oracle records time only the 1/100 of a second, and you only have 1,500 waits, which allows plenty of room for error in the significance of the 3.93 total seconds recorded.

--
Jonathan Lewis
Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

Practical Oracle 8i:  Building Efficient Databases
Publishers:  Addison-Wesley

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Jung Tjong wrote in message <3ADDEBA3.81C413A8_at_cisco.com>...


>Jonathan,

>

>The only events I saw for the sessions are  SQL*Net message to and from

>client

>and no file related events.

>Here is for one of the 5 sessions I created:

>

>       SID EVENT

>---------- ------------------------------------------------------

>TOTAL_WAITS TOTAL_TIMEOUTS TIME_WAITED AVERAGE_WAIT   MAX_WAIT

>----------- -------------- ----------- ------------ ----------

>        12 SQL*Net message to client

>       1504              0           0            0          0

>

>        12 SQL*Net message from client

>       1503              0         393   .261477046         60

>

>The numbers that seem large is the total_waits for all events and

>time_waited

>for the message from client event.

>For the 5 sessions, total_waits is 1504 for the "to client"

>and 1503 for the "from client".

>The time_waited for the "from client" ranges from 3xx to 5xx.

>I don't know the significance of these numbers. Do they look normal ?

>

Received on Wed Apr 18 2001 - 15:32:50 CDT