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From "Alan Gates (JIRA)" <>
Subject [jira] [Commented] (HIVE-9359) Export of a large table causes OOM in Metastore and Client
Date Mon, 19 Jan 2015 22:20:34 GMT


Alan Gates commented on HIVE-9359:

One question: in EximUtil.createExportDump - is there a streaming JSON writer you could use
so that we're not forced to hand-code JSON.  Maybe the JSON we're writing is simple enough,
but this looks like it could end in a mess if our JSON gets complex.

> Export of a large table causes OOM in Metastore and Client
> ----------------------------------------------------------
>                 Key: HIVE-9359
>                 URL:
>             Project: Hive
>          Issue Type: Bug
>          Components: Import/Export, Metastore
>            Reporter: Sushanth Sowmyan
>            Assignee: Sushanth Sowmyan
>         Attachments: HIVE-9359.patch
> Running hive export on a table with a large number of partitions winds up making the
metastore and client run out of memory. The number of places we wind up having a copy of the
entire partitions object wind up being as follows:
> Metastore
>    * (temporarily) Metastore MPartition objects
>    * List<Partition> that gets persisted before sending to thrift
>    * thrift copy of all of those partitions
> Client side
>    * thrift copy of partitions
>    * deepcopy of above to create List<Partition> objects
>    * JSONObject that contains all of those above partition objects
>    * List<ReadEntity> which each encapsulates the aforesaid partition objects.
> This memory usage needs to be drastically reduced.

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