Re: "DB Link are Inherently Slow" -- True or False?

  • From: Hemant K Chitale <hkchital@xxxxxxxxxxxxxx>
  • To: david@xxxxxxxxxxxxxxxxxx, Oracle List <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 15 Jul 2008 23:37:39 +0800


When you are fetching data over a DBLink (eg a SELECT for very many rows), you may find that the arraysize is small. Thus, even fetching 500 rows might result in 35 to 40 (or more) round trips depending on the arraysize.
You could trace the round-trips -- each round-trip introduces latency.

At 09:23 PM Tuesday, David Aldridge wrote:
I am being persistently told by a DBA that DB links are inherently slow and not suited to bulk transfer of data.

Does anyone have any experiences to share on the sort of practical MBytes/sec throughput we ought to be getting on a 10GBit network between two databases having no intervening firewalls, routers, or other potentially performance limiting network components? We're seeing 2MBytes/sec using data pump import in network mode with parallelsim of 10 (ie. sourcing data through a db link from another db on a different host) :(


Hemant K Chitale
http://hemantoracledba.blogspot.com


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