High water mark if that is waht you mean then.....it refers to block storage..........it is the highest block which had rows in it.......suppose you delete some rows from a table then oracle will still keep the high water mark............however if you truncate a table then the high water mark would be deleted......
if you mean high water level then.............gimme a sec i ma busy.......tryin to fig out what this heck means...
Hi,
HIGH WATER MARK indicates the level upto which the last table block reached.As soon as u enter data into the table HIGH WATER MARK also rises.When u delete the rows from the table the HIGH WATER MARK remains where it is,it doesnot fall.This leads to more I/O since when Oracle performs scan of the table it scans upto the HIGH WATER MARK.
HIGH WATER MARK is reset only when u truncate or export the table,drop the table and import it again.
In case of any help please be free to ask me at rohitsn@altavista.com
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