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From Navis류승우 <>
Subject Re: Using Hive metastore as general purpose RDBMS
Date Mon, 27 Jan 2014 04:25:31 GMT
I've heard similar use cases from NCSoft(A big game company in Korea)
platform team but they might use their own StorageHandler
(and HiveStoragePredicateHandler) implementation.

We might introduce new injection point for partition pruning, If you can
implement the logic via an interface similar with

public interface HiveStoragePredicateHandler {
  public DecomposedPredicate decomposePredicate(
    JobConf jobConf,
    Deserializer deserializer,
    ExprNodeDesc predicate);

2014-01-23 Petter von Dolwitz (Hem) <>

> Hi Alan,
> thank you for your reply. The loose idea I had was to store one row in the
> RDBMS per Hive partition so I don't think the size will be an issue
> (expecting 3000 partitions or so). The end goal was to help to decide which
> partitions that are relevant for a query. Something like adding partition
> info to the WHERE clause behind the scenes. The way the data is structured
> we currently need to look up which partitions to use elsewhere.
> I'll look into ORC for sure. Currently we do not use any of the provided
> file formats but have implemented our own InputFormat that read gzip:ed
> protobufs. I suspect that we later on should investigate a possible
> performance gain coming from moving to a another file format.
> Petter
> 2014/1/22 Alan Gates <>
>> HCatalog is definitely not designed for this purpose.  Could you explain
>> your use case more fully?  Is this indexing for better query planning or
>> faster file access?  If so, you might look at some of the work going on in
>> ORC, which is storing indices of its data in the format itself for these
>> purposes.  Also, how much data do you need to store?  Even index size on a
>> Hadoop scale data can quickly overwhelm MySQL or Postgres (which is what
>> most people use for their metastores) if you are keeping per row
>> information.  If you truly want to access an RDBMS as if it were an
>> external data store, you could implement a HiveStorageHandler for your
>> Alan.
>> On Jan 22, 2014, at 2:02 AM, Petter von Dolwitz (Hem) <
>>> wrote:
>> > Hi,
>> >
>> > I have a case where I would like to extend Hive to use information from
>> a regular RDBMS. To limit the complexity of the installation I thought I
>> could piggyback on the already existing metatstore.
>> >
>> > As I understand it, HCatalog is not built for this purpose. Is there
>> someone out there that has a similar usecase or have any input on how this
>> is done or if it should be avoided?
>> >
>> > The use case is to look up which partitions that contain certain data.
>> >
>> > Thanks,
>> > Petter
>> >
>> >
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