You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@spark.apache.org by "Cheng Su (Jira)" <ji...@apache.org> on 2020/07/31 17:44:00 UTC
[jira] [Commented] (SPARK-31470) Introduce SORTED BY clause in
CREATE TABLE statement
[ https://issues.apache.org/jira/browse/SPARK-31470?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17169042#comment-17169042 ]
Cheng Su commented on SPARK-31470:
----------------------------------
[~yumwang] - thanks for creating this jira! Would like to know more details underneath.
# For `SORT BY` here, are you more referring to local sort per spark task, or global sort, or some other techniques like z-ordering to handle multiple filters? (It seems that databricks delta already supported it - [https://databricks.com/blog/2018/07/31/processing-petabytes-of-data-in-seconds-with-databricks-delta.html])
# Where do we plan to store this metadata information in catalog, and what's the structure looking like?
# Are you more targeting improving filter performance, or other operators like join and group-by? (where I think a global sort should help save shuffle and sort for join and group-by)
# I feel it should be minor change to support the feature, but how do we drive alignments across compute engines like presto and impala in the future?
> Introduce SORTED BY clause in CREATE TABLE statement
> ----------------------------------------------------
>
> Key: SPARK-31470
> URL: https://issues.apache.org/jira/browse/SPARK-31470
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Yuming Wang
> Priority: Major
>
> We usually sort on frequently filtered columns when writing data to improve query performance. But there is no these info in the table information.
>
> {code:sql}
> CREATE TABLE t(day INT, hour INT, year INT, month INT)
> USING parquet
> PARTITIONED BY (year, month)
> SORTED BY (day, hour);
> {code}
>
> Impala, Oracle and redshift support this clause:
> https://issues.apache.org/jira/browse/IMPALA-4166
> https://docs.oracle.com/database/121/DWHSG/attcluster.htm#GUID-DAECFBC5-FD1A-45A5-8C2C-DC9884D0857B
> https://docs.aws.amazon.com/redshift/latest/dg/t_Sorting_data-compare-sort-styles.html
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org