What is a level of detail calculation? AO A calculation performed for every row of the underlying data В A calculation that allows a user to perform aggregations that result in the value at a row level A calculation that dynamically adjust the number of rows displayed based on user interactions with a filter A calculation that automatically synchronize with external D databases
Added by Stephen R.
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LOD calculations are used in data analysis to define the granularity of the data being analyzed, allowing for more complex aggregations and insights. Show more…
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Materialize temporary tables (to disk for all operations-- including selection and projection). Each integer attribute is 4 bytes. Each VarChar (string) attribute is 48 bytes. 1024B per disk block. Data is stored as an N-Ary row store. Join order is alphabetical and left-deep. Block Nested Joins only. The smallest relation (whether original or materialized) is always used for the outer loop. Join attributes are stored redundantly in the joined table. You have 6 in-memory buffers for block storage. DBMS Catalog Information: Relation R = <int id (pri key), int age, int sal, int height>; |R| = 2048 Relation S = <int id (pri key), varchar name, int teamid, int year, int rid> |S| = 4096 NDV(R, id) = 2048 and NDV(S, rid) = 2048 128 records have year>2015 and teamid > 15 Target query: Select R.sal from R,S where S.year > 2015 and S.teamid > 15 and S.rid = R.id. Query tree A π sal Blocks Read In 10 Materialized Write Out 0 σ year > 2015 and teamid>15 Blocks Read In 320 Materialized Write Out (128 * 80)/1024 = 10 R.id=S.rid Blocks Read In 32+(32/4 * 256) = 2080 Materialized Write Out 320 R S Query tree B π sal Blocks Read In 3 Mat. Write Out 0 R.id=S.rid Blocks Read In 1 + (1 * 32) = 33 Mat. Write Out (128 * 20)/ 1024 = 2.5 → 3 π sid Blocks Read In 8 Mat. Write Out (128 * 4)/ 1024 = ½ → 1 block R σ S.year > 2015 and S.teamid > 15 Blocks Read In 256 Mat. Write Out (128* 64)/1024 = 8 S
Akash M.
i. With reference to the table below explain the concept of a Domain. ii. List 2 examples from the above tables of columns that could be defined as a domain. iii. Suppose you were required to implement (create and populate) in the tables using an SQL script containing a set of CREATE TABLE and INSERT operations. List the logical sequence the tables should be populated to ensure referential integrity is preserved. iv. TotalQtySold is a column that contains derived data. Write a SQL SELECT statement that computes a value for this column for a specific product. v. When do we need to store derivable data in the table and what are the advantages
This Dashboard is related to having insight into sales in a company. If the sales manager asks you to put a filter on the bar chart to show the sales amount for January by category for the years 2013 and 2014, you should drag and drop the "order date" field to which of the following options? Note: Look at the alphabetical tags in the images. A A or B B B or C
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