| How to calculate the number of hash keys [message #501831] |
Thu, 31 March 2011 20:30  |
kytemanaic
Messages: 55
Registered: February 2009
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Member |
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Hi,
I was reading the documentation for oracle 11gr2, with reference to http://download.oracle.com/docs/cd/E11882_01/server.112/e17120/hash003.htm#sthref2548
Quote:
The following examples show how to correctly choose the cluster key and set the HASH IS, SIZE, and HASHKEYS parameters. For all examples, assume that the data block size is 2K and that on average, 1950 bytes of each block is available data space (block size minus overhead).
......
Note that 34 hash keys are assigned for each data block
The problem is I don't understand how they arrive at 34 hash keys
because another portion of the document states
Quote:
This space determines the maximum number of cluster or hash values stored in a data block. If SIZE is not a divisor of the data block size, then Oracle Database uses the next largest divisor.
if that is the case,
then number of hash keys should be 1900/55 = 34.55
which should have rounded up to 35.
Could anyone kindly clarifies? thanks a lot!
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