clustering index
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A clustering index is an ordered file with two fields; the first field is of the same type as the clustering field of the data file, and the second field is a disk block pointer. There is one entry in the clustering index for each distinct value of the clustering field, and it contains the value and a pointer to the first block in the data file that has a record with that value for its clustering field. Could any one explain to me how the clustering index have one entry for each distinct value of the clustering field While these below link to an illustrations image show a pointer to the same value 1 in the same block http://imagizer.imageshack.us/a/img538/3491/AdYgxd.png[^]
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A clustering index is an ordered file with two fields; the first field is of the same type as the clustering field of the data file, and the second field is a disk block pointer. There is one entry in the clustering index for each distinct value of the clustering field, and it contains the value and a pointer to the first block in the data file that has a record with that value for its clustering field. Could any one explain to me how the clustering index have one entry for each distinct value of the clustering field While these below link to an illustrations image show a pointer to the same value 1 in the same block http://imagizer.imageshack.us/a/img538/3491/AdYgxd.png[^]
Read the quote a few more times; it matches the diagram. Try reversing the arrows and see if that helps you understand it.
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Read the quote a few more times; it matches the diagram. Try reversing the arrows and see if that helps you understand it.
I have read it many times but I cannot understand it. One entry for each distinct value while the are 2 pointers each of which pointing to the clustering field 1 in the same block file. I tried to reverse the arrows but the same issue 2 pointers 1, and 2 to the same clustering field in the same clustering file as you can see while other pointers point to a distinct values in each clustering block.
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I have read it many times but I cannot understand it. One entry for each distinct value while the are 2 pointers each of which pointing to the clustering field 1 in the same block file. I tried to reverse the arrows but the same issue 2 pointers 1, and 2 to the same clustering field in the same clustering file as you can see while other pointers point to a distinct values in each clustering block.
Hmmm, actually it looks like the diagram is slightly confusing. The two arrows to block 1 should both be pointing to the start of block 1.
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A clustering index is an ordered file with two fields; the first field is of the same type as the clustering field of the data file, and the second field is a disk block pointer. There is one entry in the clustering index for each distinct value of the clustering field, and it contains the value and a pointer to the first block in the data file that has a record with that value for its clustering field. Could any one explain to me how the clustering index have one entry for each distinct value of the clustering field While these below link to an illustrations image show a pointer to the same value 1 in the same block http://imagizer.imageshack.us/a/img538/3491/AdYgxd.png[^]
How about this: The records with Dept_number==1 start in block 0 The records with Dept_number==2 start in block 0 The records with Dept_number==3 start in block 1 The records with Dept_number==4 start in block 2 The records with Dept_number==5 start in block 3 The records with Dept_number==6 start in block 4 The records with Dept_number==8 start in block 5
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How about this: The records with Dept_number==1 start in block 0 The records with Dept_number==2 start in block 0 The records with Dept_number==3 start in block 1 The records with Dept_number==4 start in block 2 The records with Dept_number==5 start in block 3 The records with Dept_number==6 start in block 4 The records with Dept_number==8 start in block 5
This could be intended :). With this a pointer to the first block in the data file that has a record with that value for its clustering field This seems reasonable
