Ofrecords 100million 031510 031510 prof navneet goyal

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Unformatted text preview: ggregates: Example Grocery Store 3 dimensions – Product, Location, & Time 10000 products 1000 stores 100 time periods 10% Sparsity Total no. of records = 100 million 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani 26 Aggregates: Example Hierarchies 10000 products in 2000 categories 1000 stores in 100 districts 30 aggregates in 100 time periods 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani 27 Aggregates: Example How many aggregates are possible? 1-way: Category by Store by Day 1-way: Product by District by Day 1-way: Product by Store by Month 2-way: Category by District by Day 2-way: Category by Store by Month 2-way: Product by District by Month 3-way: Category by District by Month 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani 28 Aggregates: Example What is Sparsity? Fact tables are sparse in their keys! 10% sparsity at base level means that only 10% of the products are sold on any given day (average) As we move from base level to 1-way the sparsity _Increases! _______ What affect sparsity will have on the size of the aggregate fact table? 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani 29 Aggregates: Example Let us assume that sparsity for 1way aggregates is 50% For 2-way 80% For 3-way 100% Do you agree with this? Is it logical? 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani 30 Aggregates: Example Table Base 1-way 1-way 1-way 2-way 2-way 2-way 3-way Prod. 10000 2000 10000 10000 2000 2000 10000 2000 Store 1000 1000 100 1000 100 1000 100 100 Time 100 100 100 30 100 30 30 30 Sparsity 10% 50% 50% 50% 80% 80% 80% 100% Grand Total 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani # Records 100 million 100 million 50 million 150 million 16 million 48 million 24 million 6 million 494 million 31 Aggregates: Example An increase of almost 400% Why it happened? Look at the aggregates involving Location and Time! How can we control this aggregate explosion? Do the calculations again with 500 categories and 5 time aggregates 03/15/10 03/15/10 Prof. Navneet Goyal, BITS, Pilani 32 Aggregates: Example Table Base 1-way 1-way 1-way 2-way 2-way 2-way 3-way Prod. 10000 500 10000 10000 500 500 10000 500 Store 1000 1000 100 1000 100 1000 100 100 Time 100 100 100 5 100 5 5 5 Sparsity 10% 5...
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This note was uploaded on 03/14/2010 for the course CSE SS ZG515 taught by Professor Naveneetgoyal during the Summer '10 term at Birla Institute of Technology & Science.

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