Equality in Scala : A Dilemna or Compiler Smartness

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Calculating Top N items per Group (Without Window Functions)

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These kinds of questions are more common than you think: Out of a list of Twitter users, find their N recent tweets. Out of all the cities, find the top N cities in each country by population. Out of all orders on the e-commerce website, find the top N recent orders for each customer. Solving these questions becomes pretty easy if we use a window function like row_number(), but solving this without any window function makes the task challenging. Here we will see both approaches. Question: Display the top 3 recent values from every group Table : groups                                            Required Output: Method 1 (Using Window Function): WITH ranked AS ( SELECT group_id,value, ROW_NUMBER() OVER (PARTITION BY group_id ORDER BY value DESC ) AS rn FROM groups ) SELECT group_id,value FROM ranked WHERE rn <= 3 ; ...
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Inside Out - Leetcode SQL

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Parquet is best suitable for Nested Data , But Why ?

Yes, all the folks who are working with big data must have heard this statement, but very few of them are aware of the real reason why parquet has the upper hand when it comes to storing nested data. It is the underlying architecture and hierarchical data model of parqeut which is making things easy for the nested data. This architecture of parqeut follows the Dremel paper published by Google. Here is the blog post which justifies the famous statement: https://blog.twitter.com/engineering/en_us/a/2013/dremel-made-simple-with-parquet
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