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Home -> Community -> Mailing Lists -> Oracle-L -> Re[2]: SQL*Net overhead
At the risk of someone flaming me badly;
Be careful with TDU/SDU. First these two have to be the same value or some very qwirky things begin to happen. Second they control the amount of data SQL*Net sends to the protocol adapter at one time, not the amount of data that is inside the packet. If you can get TDU/SDU to be equal to an even multiple of the real data packet size then things work out nicely. On the other hand if it's not an even multiple then you waste network bandwidth. As an example: If your typical packet size is 2K (which I understand is rather common) then you can set TDU/SDU to 2K, 4K, 6K, etc... (In actual bytes that is). In this case SQL*Net sends an amount of data to the TCP stack that can be equally broken up into packets, filling the packet. In this case to get say 10K of data from the database to the client takes 5 packets. If, on the other hand, you set it for 3K then SQL*Net sends the data in 1.5 packet size chunks thereby taking 7 packets (Each SQL*Net chunk takes 2 packets to send & this is 3 and a third chunks).
For HP-UX and Windows 95/NT sizes of 2048, 4096, and 8192 work very well. Anything above 8192 seems to slow things down.
Dick Goulet
____________________Reply Separator____________________Subject: Re: SQL*Net overhead
Nope, but think you can tune it using TDU/SDU in listener.ora and tnsnames.ora. The max value (last time I looked) was 32768.
Steve.Parker_at_lis.co.uk wrote:
>
> Has anyone performed any calculations on the
> overhead that SQL*Net imposes on top of the data
> that is passed between a client and server.
>
> e.g. if the client requests 1000 rows where each row is 345 bytes
> in size, what is the overall size of the data passed over the
> network, assuming TCP/IP ?
>
> Thanks in advance
>
> Steve Parker
> Technical Consultant
> LIS
>
> Logistics & Internet Systems Ltd.
> Knaves House, Knaves Beech Business Centre
> Loudwater, High Wycombe
> Buckinghamshire , HP10 9QR, United Kingdom
> Telephone: +44 (0) 1628 859800
> Facsimile: +44 (0) 1628 532688
> E Mail: steve.parker_at_lis.co.uk
>
> --
> Author:
> INET: Steve.Parker_at_lis.co.uk
>
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-- Author: Suzy Vordos INET: lvordos_at_uswest.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You mayReceived on Thu Jun 22 2000 - 12:39:56 CDT
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