![]() Initially assigns the ALL distribution style to a small table. ![]() Sort key columns govern how data is physically sorted for a table on disk and can be. ![]() Selecting the right kind requires knowledge of the queries that you plan to execute. For example, if AUTO distribution style is specified, Amazon Redshift Amazon Redshift does not have indexes it does, however, have sort keys. Amazon Redshift supports two different types of Sort Keys, Compound Sort Keys, and Interleaved Sort Keys. Possible distribution styles are as follows:ĪUTO: Amazon Redshift assigns an optimal distribution style based on the tableĭata. For more information, see Working with data distribution styles. You can read about more techniques for optimizing Amazon Redshift performance. Depending on your data and cluster size, VACUUM REINDEX takes significantly longer than VACUUM FULL. By specifying a sort key, you can tell Redshift to only look in the part of the table. Without a sort key, Redshift has to scan the entire table to find the relevant data, which can take a long time. This tutorial will explain how to select appropriate sort keys. An INTERLEAVED sort key can use a maximum of eight columns. Sort keys are used in Redshift to improve query performance by allowing the database to more quickly narrow down the data that is being searched. In our case (and please be advised to analyze how you use/query your own data) we used timestamp as first sortkey. Amazon Redshift stores your data in 1MB blocks and for each block it keeps metadata about. If you have a table of sales and you select the purchase time as the sort key, the data will be ordered from oldest to newest purchase. The distribution style that you select for tables affects the overall One key step towards tuning your Amazon Redshift database is carefully selecting sort keys to optimize your queries. We are also using Redshift and we have about 2 billion records (+20 million every day) and I have to say, the less selective the sortkey is, the more ahead it should be in the sortkey list. A sort key is a field in your table that determines the order in which the data is physically stored in the database. As a table grows, the distribution of the values in the sort key columns can change, or skew, especially with date or timestamp columns. Keyword that defines the data distribution style for the whole table.Īmazon Redshift distributes the rows of a table to the compute nodes according to theĭistribution style specified for the table. When tables are initially loaded, Amazon Redshift analyzes the distribution of the values in the sort key columns and uses that information for optimal interleaving of the sort key columns.
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