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author | Jason White <jason.white@shopify.com> | 2015-11-02 10:49:06 -0800 |
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committer | Davies Liu <davies.liu@gmail.com> | 2015-11-02 10:49:06 -0800 |
commit | f92f334ca47c03b980b06cf300aa652d0ffa1880 (patch) | |
tree | f692cc7d9ddae0329ab0b7b8201e0e4a3a9b17c9 /python | |
parent | 71d1c907dec446db566b19f912159fd8f46deb7d (diff) | |
download | spark-f92f334ca47c03b980b06cf300aa652d0ffa1880.tar.gz spark-f92f334ca47c03b980b06cf300aa652d0ffa1880.tar.bz2 spark-f92f334ca47c03b980b06cf300aa652d0ffa1880.zip |
[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
Author: Jason White <jason.white@shopify.com>
Closes #9392 from JasonMWhite/createDataFrame_without_take.
Diffstat (limited to 'python')
-rw-r--r-- | python/pyspark/sql/context.py | 8 |
1 files changed, 1 insertions, 7 deletions
diff --git a/python/pyspark/sql/context.py b/python/pyspark/sql/context.py index 79453658a1..924bb6433d 100644 --- a/python/pyspark/sql/context.py +++ b/python/pyspark/sql/context.py @@ -318,13 +318,7 @@ class SQLContext(object): struct.names[i] = name schema = struct - elif isinstance(schema, StructType): - # take the first few rows to verify schema - rows = rdd.take(10) - for row in rows: - _verify_type(row, schema) - - else: + elif not isinstance(schema, StructType): raise TypeError("schema should be StructType or list or None, but got: %s" % schema) # convert python objects to sql data |