[jira] [Resolved] (SPARK-14166) Add deterministic sampling like in Hive

["Hyukjin Kwon (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-14166?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hyukjin Kwon resolved SPARK-14166.
----------------------------------
    Resolution: Incomplete

> Add deterministic sampling like in Hive
> ---------------------------------------
>
>                 Key: SPARK-14166
>                 URL: https://issues.apache.org/jira/browse/SPARK-14166
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 2.0.0
>            Reporter: Ruslan Dautkhanov
>            Priority: Minor
>              Labels: bulk-closed, sample, sql
>
> Would be great to have Spark support deterministic sampling too
> {quote}
> set hive.sample.seednumber=12345;
> SELECT *
> FROM table_a TABLESAMPLE(BUCKET 17 OUT OF 25 ON individual_id);
> {quote}
> Notice sampling is based on a hash(individual_id).
> https://cwiki.apache.org/confluence/display/Hive/LanguageManual+Sampling
> In this case sampling is deterministic. When we have new data loads, we get very stable samples and use it all the time in Hive.
> The only reason for "BUCKET x OUT OF y " syntax in Hive is "If the columns specified in the TABLESAMPLE clause match the columns in the CLUSTERED BY clause, TABLESAMPLE scans only the required hash-partitions of the table."



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