GitHub user JasonMWhite opened a pull request:
https://github.com/apache/spark/pull/9392
[SPARK-11437] [PySpark] Don't .take when converting RDD to DataFrame with
provided schema
When creating a DataFrame from an RDD in PySpark, `createDataFrame` calls
`.take(10)` to verify the first 10 rows of the RDD match the provided schema.
Similar to https://issues.apache.org/jira/browse/SPARK-8070, but that issue
affected cases where a schema was not provided.
Verifying the first 10 rows is of limited utility and causes the DAG to be
executed non-lazily. If necessary, I believe this verification should be done
lazily on all rows. However, since the caller is providing a schema to follow,
I think it's acceptable to simply fail if the schema is incorrect.
@marmbrus We chatted about this at SparkSummitEU. @davies you made a
similar change for the infer-schema path in
https://github.com/apache/spark/pull/6606
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/JasonMWhite/spark createDataFrame_without_take
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/9392.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #9392
----
commit a7c395f9fe7bf43b1e63af060b425fa6047b25f9
Author: Jason White <jason.wh...@shopify.com>
Date: 2015-10-31T21:17:37Z
don't .take when converting RDD to DataFrame with provided schema
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