August 6, 2010 at 11:17 am
Hi,
We have several web applications running using the SQL Server 2000 as the back end. These are mainly reporting applications where the data access mainly involves data read and no data writes.
My questions is whether these operations are generally termed as Sequential IO operations or Random IO Operations? What is the difference?
thanks in advance,
TZ
August 6, 2010 at 11:42 am
tzones2006 (8/6/2010)
We have several web applications running using the SQL Server 2000 as the back end. These are mainly reporting applications where the data access mainly involves data read and no data writes.My questions is whether these operations are generally termed as Sequential IO operations or Random IO Operations? What is the difference?
Lets focus on the "select" part of it.
In general you can find two kind of read operations triggered by a "select" statement, they are:
Sequential reads - when you are perfoming a full table scan and,
Direct reads - when you are accessing a data block after going to an index or you are accessing the datablock by rowid.
Different technologies call those operations in very dissimilar ways.
Just as an example Oracle calls "sequential read" a read that comes "in sequence to an index access" while it calls "scatered read" a read caused by a full table scan.
_____________________________________
Pablo (Paul) Berzukov
Author of Understanding Database Administration available at Amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.Viewing 2 posts - 1 through 1 (of 1 total)
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