Difference between Nested Loop & Hash Join ??

[fasi rehman]

Hi Folks,   Can anyone explain me the difference between nested loop & hash join ??   Regards, Fasi

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[ddf]

On Sep 29, 10:58 am, fasi rehman <fasi_...@yahoo.co.in> wrote:
> Hi Folks,
>  
> Can anyone explain me the difference between nested loop & hash join ??
>  
> Regards,
> Fasi
>

>       From cricket scores to your friends. Try the Yahoo! India Homepage!http://in.yahoo.com/trynew


Hash join:

Oracle creates a hash key for the joined column values, then creates a
hash table of all values in the joined columns. Matching hash values
are retained for the result set.

Nested loop:

Drivinig table is the 'outer' loop, driven table is the 'inner
loop'. Value in outer loop is returned, values from driven table are
chosen and matches are retained. When driven table result set is
exhausted inner loop terminates, outer loop increments and inner loop
starts all over again. Continues until outer loop is exhausted.


David Fitzjarrell