When you set the joining columns of joining tables as distribution keys, the joining rows from both tables are collocated on the compute nodes. KEY: The data is distributed by the values in the DISTKEY column. Row IDs are used to determine the distribution, and roughly the same number of rows are distributed to each node. It is not possible to specify more than one DISTKEY for each recommended optimization.ĮVEN: The data in the table is spread evenly across the nodes in a cluster in a round-robin distribution. Dist KeysĭISTKEYs are not automatically recommended by the system and they need to be manually created by the user. The system will create then a SORTKEY with one column or with multiple columns if the highest freq index is SINGLE or MULTIPLE, respectively.Ĭolumns that are normally recommended for index creation are used to define dist and sort keys. Since it is possible to specify only one SORTKEY(with one or more columns) at the table level, we decided to create a SORTKEY corresponding to the recommended index (with kind SINGLE or MULTIPLE) with the highest frequency. SORTKEYs are created analyzing the currently recommended indexes collected for each optimization.Īccording to the documentation, SORTKEYs can be specified both at column and table levels. It is possible to specify only one SORTKEY column (at column level) or multiple columns if defined at the table level. With respect to indexes, distkeys and sortkeys must be defined when the table is created. ![]() Redshift does not support indexes but supports distribution and sort keys that can be used to improve the performance of queries. BucketPrefix translator property is available since 2.1.7ĬreateBucket translator property is available since 2.1.15
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |