GitHub user HyukjinKwon opened a pull request:
https://github.com/apache/spark/pull/17492
[SPARK-19641][SQL] JSON schema inference in DROPMALFORMED mode produces
incorrect schema for non-array/object JSONs
## What changes were proposed in this pull request?
Currently, when we infer the types for vaild JSON strings but object or
array, we are producing empty schemas regardless of parse modes as below:
```scala
scala> spark.read.option("mode", "DROPMALFORMED").json(Seq("""{"a": 1}""",
""""a"""").toDS).printSchema()
root
scala> spark.read.option("mode", "FAILFAST").json(Seq("""{"a": 1}""",
""""a"""").toDS).printSchema()
root
```
This PR proposes to handle parse modes in type inference.
After this PR,
```scala
scala> spark.read.option("mode", "DROPMALFORMED").json(Seq("""{"a": 1}""",
""""a"""").toDS).printSchema()
root
|-- a: long (nullable = true)
```
```
scala> spark.read.option("mode", "FAILFAST").json(Seq("""{"a": 1}""",
""""a"""").toDS).printSchema()
java.lang.RuntimeException: Failed to infer a common schema. Struct types
are expected but string was found.
```
This PR is based on
https://github.com/NathanHowell/spark/commit/e233fd03346a73b3b447fa4c24f3b12c8b2e53ae
and I and @NathanHowell talked about this in
https://issues.apache.org/jira/browse/SPARK-19641
## How was this patch tested?
Unit tests in `JsonSuite` for both `DROPMALFORMED` and `FAILFAST` modes.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/HyukjinKwon/spark SPARK-19641
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17492.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 #17492
----
commit dc24522502b3f7816d539da2c8efb09a3515bb70
Author: hyukjinkwon <[email protected]>
Date: 2017-03-31T04:52:27Z
JSON schema inference in DROPMALFORMED mode produces incorrect schema
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