skr13
Last Activity: Dec 28 '10, 12:32 AM
Joined: Mar 1 '10
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Thanks a lot jkmyoung and weaknessforcats . I am doing this using multi dimensional linked lists and will probably use multimap. I have done bit vector mapping, but multimap seems to be more easier in processing the queries. I appreciate your help -
I do get what you are saying. But I need to precompute the data cubes and store them and the fire the queries. If there are, say 3 dimension(attri butes), I need to abstract the dimensions and compute the cuboids AB, BC, AC, A, B and C. I have done this statically. After that I use a bit map indexing scheme to handle the queries. But I can't imagine n dimensions using linked lists. I have this idea. In the linked list, each node will have n pointers...Leave a comment:
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I am using C++. For each attribute in the table there will be 1 dimension. If the table has 20 dimensions then I will need a 20-dimensional array. This 20 dimensional array will be a sparse array. Linked lists are slow but the memory will not be wasted. And just curious, how do you create 20D array at the runtime?Leave a comment:
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I need to query the table. For eg, SELECT FROM TABLE where CITY=X and TIME=t1.
For this i need to pre-compute the data cubes and store them. Actually I have the table for chunks.
struct chunks
{
int value,offset;
struct chunks *link;
};
It would be easier if the used arrays to compute data cubes but the problem is I will know the array dimension only during runtime. I would appreciate...Leave a comment:
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I used linked lists to create an element in the list only if the data is present and used the dimensionality to calculate the offset. Now i am storing the data and the offset in each element of the list, thereby I have saved lot of memory.Leave a comment:
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I will be using the chunks to aggregate the values present in them. For eg,
chunkArray[0][0][0] = 5;
chunkArray[0][0][7] = 9;
when i aggregate keeping the first 2 indices constant, i ll get 13.
Say A represents CITY, B represent ITEM and C represents TIME.
These are the 3 dimensions for the chunk.
CITY ITEM TIME
0- X 0-i1 0-t1
1- Y 1-i2 1-t2
...Leave a comment:
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Multidimensional sparse arrays using linked lists
Hi,
I am implementing an aggregation model to compute data cubes.
I have implemented the multiway array aggregation statically. That is if there are, say, 4 dimensions each of cardinality 16 and the chunk size of 4, I create chunkArray[4][4][4][4] and insert the measure at the appropriate position and aggregate the measure. The chunkArray is a sparse array and static implementation is not efficient. In order the dynamically...
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