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From Francis Liu <>
Subject Re: Is HiveMetastoreClient a public interface?
Date Fri, 30 Mar 2012 00:55:19 GMT
Hi Carl,

I see, thanks for clarifying that. It'd be brittle to write our own client
as HiveMetaStoreClient is not really that "thin" since it is already
performing callbacks for HiveMetaHook and someone might decide to add more
(or remove) logic into it.

The java API is an ask from one of our users for Hcatalog. Given that
HiveMetaStoreClient is a thin wrapper around public apis, then change
shouldn't be drastic? It seems the cleaner way to go about it is to create
an hcat client wrapper around HiveMetaStoreClient and have HCatClient as


On 3/29/12 3:34 PM, "Carl Steinbach" <> wrote:

>Hi Francis,
>The HiveMetaStoreClient library is a thin wrapper layer written around the
>Thrift generated client code. It is not a public API and is subject to
>change in the future. If "experts only" is doable, then I recommend
>integrating directly at the Thrift API level (which is a public API), e.g.
>call the Thrift generated code directly instead of accessing it through
>HiveMetaStoreClient library.
>On Thu, Mar 29, 2012 at 2:05 PM, Francis Liu <> wrote:
>> Hi Edward,
>> We would also need other apis such as dropping partitions and tables as
>> well as retrieving delegation tokens. "Experts only" is doable. The main
>> concern of it being public is wether in future releases, Hive developers
>> will do their best to make sure the interface is backwards compatible.
>> -Francis
>> On 3/29/12 1:04 PM, "Edward Capriolo" <> wrote:
>> >Ideally you want to do everything through the hiveQL language. Calling
>> >the read only methods are safe and would be easier/better then Calling
>> >'show tables' and attempting to parse. But I would consider the rest
>> >of the interface for "experts" only. Also this interface can change
>> >slightly between versions making it harder to build code against.
>> >
>> >Edward
>> >
>> >On Thu, Mar 29, 2012 at 2:50 PM, Francis Liu <> wrote:
>> >> No reponse from the user list. Reposting in the dev list:
>> >>
>> >> Hi,
>> >>
>> >> It seems like the HiveMetaStoreClient is the only way to
>> >>programmatically
>> >> access (and retreive)  the metastore for DDL and metadata queries as
>> >>well as
>> >> retrieving delegation tokens. It isn't documented anywhere, so I'd
>> >>to
>> >> know if it is advisable to have code make use of this directly or is
>> >>this an
>> >> internal API?  If the latter what would be the recommended way of
>> >> programmatically doing the previously mentioned operations?
>> >>
>> >> -Francis
>> >>
>> >>

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