[jira] [Updated] (SPARK-25396) Read array of JSON objects via an Iterator

["Dongjoon Hyun (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-25396?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dongjoon Hyun updated SPARK-25396:
----------------------------------
    Affects Version/s:     (was: 2.4.0)
                       3.0.0

> Read array of JSON objects via an Iterator
> ------------------------------------------
>
>                 Key: SPARK-25396
>                 URL: https://issues.apache.org/jira/browse/SPARK-25396
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.0.0
>            Reporter: Maxim Gekk
>            Priority: Minor
>
> If a JSON file has a structure like below:
> {code}
> [
>       {
>          "time":"2018-08-13T18:00:44.0860000Z",
>          "resourceId":"some-text",
>          "category":"A",
>          "level":2,
>          "operationName":"Error",
>          "properties":{...}
>      },
>     {
>          "time":"2018-08-14T18:00:44.0860000Z",
>          "resourceId":"some-text2",
>          "category":"B",
>          "level":3,
>          "properties":{...}
>      },
>   ...
> ]
> {code}
> it should be read in the `multiLine` mode. In this mode, Spark read whole array into memory in both cases when schema is `ArrayType` and `StructType`. It can lead to unnecessary memory consumption and even to OOM for big JSON files.
> In general, there is no need to materialize all parsed JSON record in memory there: https://github.com/apache/spark/blob/a8a1ac01c4732f8a738b973c8486514cd88bf99b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/json/JacksonParser.scala#L88-L95 . So, JSON objects of an array can be read via an Iterator. 



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