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Posted to issues@spark.apache.org by "Davies Liu (JIRA)" <ji...@apache.org> on 2014/11/18 21:21:33 UTC
[jira] [Updated] (SPARK-4476) Use MapType for dict in json which
has unique keys in each row.
[ https://issues.apache.org/jira/browse/SPARK-4476?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Davies Liu updated SPARK-4476:
------------------------------
Description:
For the jsonRDD like this:
{code}
""" {a: 1} """
""" {b: 2} """
""" {c: 3} """
""" {d: 4} """
""" {e: 5} """
{code}
It will create a StructType with 5 fileds in it, each field come from a different row. It will be a problem if the RDD is large. A StructType with thousands or millions fields is hard to play with (will cause stack overflow during serialization).
It should be MapType for this case. We need a clear rule to decide StructType or MapType will be used for dict in json data.
cc [~yhuai] [~marmbrus]
was:
For the jsonRDD like this:
{code}
""" {a: 1} """
""" {b: 2} """
""" {c: 3} """
""" {d: 4} """
""" {e: 5} """
{code}
It will create a StructType with 5 fileds in it, each field come from a different row. It will be a problem if the RDD is large. A StructType with thousands or millions fields is hard to play with (will cause stack overflow during serialization).
It should be MapType for this case. We need a clear rule to decide StructType or MapType will be used for dict in json data.
> Use MapType for dict in json which has unique keys in each row.
> ---------------------------------------------------------------
>
> Key: SPARK-4476
> URL: https://issues.apache.org/jira/browse/SPARK-4476
> Project: Spark
> Issue Type: New Feature
> Components: SQL
> Reporter: Davies Liu
> Priority: Critical
>
> For the jsonRDD like this:
> {code}
> """ {a: 1} """
> """ {b: 2} """
> """ {c: 3} """
> """ {d: 4} """
> """ {e: 5} """
> {code}
> It will create a StructType with 5 fileds in it, each field come from a different row. It will be a problem if the RDD is large. A StructType with thousands or millions fields is hard to play with (will cause stack overflow during serialization).
> It should be MapType for this case. We need a clear rule to decide StructType or MapType will be used for dict in json data.
> cc [~yhuai] [~marmbrus]
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