In my data ‘table1’, there are multiple records for each app_id. I’m trying to get a latest app_id entry. Which one of the below queries would be quick or better to consider in terms of performance …
Tag: window-functions
Window functions filter through current row
This is a follow-up to this question, where my query was improved to use window functions instead of aggregates inside a LATERAL join. While the query is now much faster, I’ve found that the results are not correct. I need to perform computations on x year trailing time frames. For example, price_to_maximum_earnings is computed per row by getting max(earnings) over
Syntax Error trying to return row number from database
SELECT ROW_NUMBER()OVER(ORDER BY id), x, y, id FROM coordonnees ORDER BY id I’m trying to return the row number of each row (the table named coordonnees with 3 columns: id, x, y), but this code doesn’…
What’s the default window frame for window functions
Running the following code: The result is: There is no window frame defined in the above code, it looks the default window frame is rowsBetween(Window.unboundedPreceding, Window.currentRow) Not sure my understanding about default window frame is correct Answer From Spark Gotchas Default frame specification depends on other aspects of a given window defintion: if the ORDER BY clause is specified and
PostgreSQL unnest() with element number
When I have a column with separated values, I can use the unnest() function: How can I include element numbers? I.e.: I want the original position of each element in the source string. I’ve tried with window functions (row_number(), rank() etc.) but I always get 1. Maybe because they are in the same row of the source table? I know
SQL: difference between PARTITION BY and GROUP BY
I’ve been using GROUP BY for all types of aggregate queries over the years. Recently, I’ve been reverse-engineering some code that uses PARTITION BY to perform aggregations. In reading through all the documentation I can find about PARTITION BY, it sounds a lot like GROUP BY, maybe with a little extra functionality added in. Are they two versions of the