benj created DRILL-7602:
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Summary: Possibility to force repartition on read/select
Key: DRILL-7602
URL: https://issues.apache.org/jira/browse/DRILL-7602
Project: Apache Drill
Issue Type: Improvement
Components: Execution - Flow, Query Planning & Optimization
Affects Versions: 1.17.0
Reporter: benj
It will be nice and usefull ion certain situations to have the capacity to do
repartition like in spark
(https://spark.apache.org/docs/latest/rdd-programming-guide.html)
either an automatically repartition in certain limit or possibility to indicate
the desired repartition or both options.
The only way (that I know now) to do that with Drill is to change
_store.parquet.block-size_ and regenerate the input file then do the request
(but it will be nice to have the ability to do that on read)
illustration : with 2 Parquets files _file1_ of 50Mo (1 million rows) and
_file2_ of 1Mo (5000 rows)
{code:sql}
CREATE TABLE dfs.test.`result_from_1_parquet` AS
(SELECT * FROM dfs.test.`file2` INNER JOIN dfs.test.`file1` ON ...)
=> ~ 50min
-- Tody we have to change the parquet block size to force multiple parquet files
ALTER SESSION SET `store.parquet.block-size` = 1048576;
-- Repartition data
CREATE TABLE dfs.test.`file1_bis` AS (SELECT * FROM dfs.test.`file1`);
-- then Launch the request
CREATE TABLE dfs.test.`result_from_1_parquet` AS
(SELECT * FROM dfs.test.`file2` INNER JOIN dfs.test.`file1_bis` ON ...)
=> ~ 1min
{code}
So it's possible to save a lot of time (depending of configuration of cluster)
by simply forcing more input file.
it would be useful not to have to regenerate the files with the ideal
fragmentation before request.
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