![]() ![]() However, every query is always executed on a single CPU of a single machine. Most relational databases execute multiple queries in parallel if they have access to many cores/servers. It is best suited for storing OLAP workloads, summing over a long history. For more information about SORTKEY, see CREATE TABLE.The Amazon Redshift technology is a column-oriented storage in the cloud. ![]() ![]() When you alter the sort key, Amazon Redshift reorders the data. When data is loaded into a table, the data is loaded in the order of the sort key. Consider the following: You can define a maximum of 400 columns for a sort key per table. For more information about DISTSTYLE, see CREATE TABLE.ĪLTER SORTKEY ( column_name ) A clause that changes When specifying DISTSTYLE KEY, the data is distributed by the values in the DISTKEY column. The ALTER DISTKEY command is not supported for tables with interleaved sort keys. You can only run one ALTER DISTKEY command on a table at a time. If ALTER DISTKEY is running, then foreground vacuum returns an error. ![]() If ALTER DISTKEY is running, then background vacuum doesn't start on a table. If VACUUM is already running, then ALTER DISTKEY returns an error. Consider the following: VACUUM and ALTER DISTKEY cannot run concurrently on the same table. Users can modify sort keys for a given table as many times as needed and they can alter sort keys for multiple tables simultaneously.įor more information ALTER SORT KEY, please refer to the documentation.ĪLTER DISTKEY column_name or ALTER DISTSTYLE KEY DISTKEY column_name AĬlause that changes the column used as the distribution key of a Redshift will take care of adjusting data layout behind the scenes and table remains available for users to query. With the new ALTER SORT KEY command, users can dynamically change the Redshift table sort keys as needed. Currently Redshift customers who desire to change the sort keys after the initial table creation will need to re-create the table with new sort key definitions. The sort keys are used to maintain the sort order of the Redshift tables and allows the query engine to achieve high performance by reducing the amount of data to read from disk and to save on storage with better compression. The new capability simplifies user experience in maintaining the optimal sort order in Redshift to achieve high performance as their query patterns evolve and do it without interrupting the access to the tables.Ĭustomers when creating Redshift tables can optionally specify one or more table columns as sort keys. The maximum number of columns you can define in a single table is 1,600.Īmazon Redshift now supports changing table sort keys dynamically Amazon Redshift now enables users to add and change sort keys of existing Redshift tables without having to re-create the table. The maximum column name length is 127 characters longer names are truncated to 127 characters. You cannot use an ALTER TABLE ADD COLUMN command to modify the following table and column attributes: You cannot add a column that is the distribution key (DISTKEY) or a sort key (SORTKEY) of the table. You can add only one column in each ALTER TABLE statement. In the past when I ran into this kind of situation I created a new table and copied the data from the old one into it.Īdds a column with the specified name to the table. The new capability simplifies user experience in maintaining the optimal sort order in Redshift to achieve high performance as their query patterns evolve and do it without interrupting the access to the tables.Īt the moment I think its not possible (hopefully that will change in the future). Amazon Redshift now enables users to add and change sort keys of existing Redshift tables without having to re-create the table. ![]()
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