This list contains the records that we will get rid of by removing from the sample Redshift table. Order by total_duplicates desc, venueid, duplicate_rn Īs seen below I numbered each repeating row using ROW_NUMBER() function and listed only the ones with value is equal or greater to 2 Select * from duplicates_cte where duplicate_rn > 1 ROW_NUMBER () OVER (PARTITION BY venueid) as duplicate_rn, *
Redshift rank function how to#
In this Amazon Redshift SQL tutorial, I want to demonstrate how to identify duplicate records in a Redshift database table and delete duplicates rows or remove duplicates from Redshift table using SQL.ĬOUNT(*) OVER (PARTITION BY venueid) as total_duplicates, If there are duplicate rows for example, these will prevent the activation of the constraints. On the other hand, on OLAP data platforms (OLAP stands for On-line Analytical Processing), these constraints are optional.Įspecially even the database enforces these constraints, for the sake of performance especially during data ingestion step, I mean while inserting huge amount of data into the data warehouse it is best practise to disactivate or disable the constraints on the target database table and then import data or copy data from external source into database table.Īt this step, while data import is completed and it is time to validate and ensure the data quality, database SQL developers and database administrators can try to active the constraints on table level. Unique key, primary key, foreign key and other constraints are enforced on OLTP (On-line Transaction Processing) database platforms to ensure data integrity. Just like the case for many data warehouse platforms, although Amazon Redshift database supports creation for primary key, foreign key constraints Redshift does not enforce these constraints.
In this Amazon Redshift tutorial for SQL developers I want to show how to delete duplicate rows in a database table using SQL commands. Delete Duplicate Rows from Amazon Redshift Database Table using SQL
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