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From Mich Talebzadeh <mich.talebza...@gmail.com>
Subject Re: Difference between MANAGED_TABLE and EXTERNAL_TABLE in org.apache.hadoop.hive.metastore.TableType
Date Thu, 01 Dec 2016 21:29:18 GMT
Adding to Alan's points external tables are used often as a staging area.
For example, ingesting data from HDFS location on a daily basis and putting
that data into Hive managed tables. That location of that external table
can change pointing to a new HDFS directory created by say Flume etc
through ALTER table like below

ALTER TABLE ${DATABASE}.EXTERNALMARKETDATA set location
'hdfs://rhes564:9000/data/prices/${TODAY}';


HTH

Dr Mich Talebzadeh



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On 1 December 2016 at 17:53, Alan Gates <alanfgates@gmail.com> wrote:

> Hive does not assume that it owns the data for an external table.  Thus
> when an external table is dropped, the data is not deleted.  People often
> use this as a way to load data into a directory in HDFS and then “cast” a
> table structure over it by creating an external table with that directory
> as its location.
>
> Alan.
>
> > On Dec 1, 2016, at 06:15, Huang Meilong <imsrch@outlook.com> wrote:
> >
> > Hi all,
> >
> > I found an enum TableType in package org.apache.hadoop.hive.metastore.
> What's the difference between MANAGED_TABLE and EXTERNAL_TABLE?
> >
> > Will the table be an EXTERNAL TABLE with setting table type
> EXTERNAL_TABLE when creating table?
> >
> > I found the code to determine whether a table is an external table in
> MetaStoreUtils.java
> > https://github.com/apache/hive/blob/master/metastore/
> src/java/org/apache/hadoop/hive/metastore/MetaStoreUtils.java#L1425
> >
> > I'm confused what is EXTERNAL_TABLE in TableType for?
>
>

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