If you are not sure about which column should be used in DISTKEY, probably EVEN distribution style is your best choice. data is distributed using round-robin techniques. Leaving out DISTKEY in Redshift distributionīy default, Amazon Redshift database data distribution uses the EVEN distribution style i.e. When data is inserted into table, hashed value will be pointing to only two slices on the node and data will be place on those slices, thus causing skew. Redshift Table Data Skew and How to avoid itįor example, consider Reshift table is distributed on the column that contains only flags such as Y or N.It is very important to identify the correct and proper distribution key when creating table definition and that require the extremely good knowledge on data. Bad distribution key can result in uneven distribution of a table across slices and will cause skew, of course that will hamper the system performance. If you specify the DISTKEY, Amazon Redshift uses a hash of the DISTRIBUTION KEY (DISTKEY) to distribute data records amongst nodes.Ī distribution method that distributes data evenly across all node slices is the single most important factor that can increase overall query performance. Amazon Redshift Distribution Types and Examples. You may read about distribution types and best practices: When you create tables you will have to tell the system which distribution it should use. Amazon Redshift uses the three types of distribution EVEN, KEY and ALL.
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