Hive distinct vs group by. However, I tried using Distinct right after and it worked.

Hive distinct vs group by. Consider a sales table with customer ID, name, product, and price. The Hive basic built-in aggregate functions are usually used with the GROUP BY clause. Sep 11, 2018 · If you use groupby () executors will makes the grouping, after send the groups to the master which only do the sum, count, etc by group however distinct () check every columns in executors () and try to drop the duplicates after the executors sends the distinct dataframes to the master, and the master check again the distinct values with the all columns. I think this is the main reason. Using DISTINCT during ETL (Extract, Transform, Load) processes ensures that only clean and unique data is stored in Hive tables. and you'd only get 2 records when using distinct colA, ColB as the Sep 12, 2024 · Why I Thought GROUP BY Was Always the Best Choice for SQL Optimization—Until I Tested the Data As a data professional, I often relied on GROUP BY for optimizing SQL queries, believing it to be a Dec 15, 2017 · Gunther is right, Hive planner rewrites distinct using group by, so it doesn't matter what do you use from performace point of view. Hive de-duplication: distinct and group by The following two cases introduce the underlying principles of distinct and group by. If there is no GROUP BY clause specified, it aggregates over the whole table by default. There is no reason to believe that just because group by and distinct are equivalent on MS SQL (of some specific version) this also applies to Hive. The question you linked is specifically about MS SQL Server behaviour. pwcn3 zpmf uhut74 ie33g tec6ym vza 4m3c km8q 7kbzp na