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https://issues.apache.org/jira/browse/SPARK-15193?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15278393#comment-15278393
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Nicholas Chammas commented on SPARK-15193:
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Nope, a sampling ratio of 1.0 and None mean [different
things|http://spark.apache.org/docs/1.6.1/api/python/pyspark.sql.html#pyspark.sql.SQLContext.createDataFrame]:
{quote}
If schema inference is needed, samplingRatio is used to determined the ratio of
rows used for schema inference. The first row will be used if samplingRatio is
None.
{quote}
createDataFrame() is not consistent with jsonRDD() as of 1.6.1.
Looking in master, I can't seem to find jsonRDD() for Python anymore, so
perhaps that got removed. So actually, it looks like the default _did_ get
standardized, but to None. :/
> samplingRatio should default to 1.0 across the board
> ----------------------------------------------------
>
> Key: SPARK-15193
> URL: https://issues.apache.org/jira/browse/SPARK-15193
> Project: Spark
> Issue Type: Improvement
> Components: PySpark, SQL
> Reporter: Nicholas Chammas
> Priority: Minor
>
> The default sampling ratio for {{jsonRDD}} is
> [1.0|http://spark.apache.org/docs/1.6.1/api/python/pyspark.sql.html#pyspark.sql.SQLContext.jsonRDD],
> whereas for {{createDataFrame}} it's
> [{{None}}|http://spark.apache.org/docs/1.6.1/api/python/pyspark.sql.html#pyspark.sql.SQLContext.createDataFrame].
> I think the default sampling ratio should be 1.0 across the board. Users
> should have to explicitly supply a lower sampling ratio if they know their
> dataset has a consistent structure. Otherwise, I think the "safer" thing to
> default to is to check all the data.
> Targeting this for 2.0 in case we consider it a breaking change that would be
> more difficult to get in later.
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