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https://issues.apache.org/jira/browse/HIVE-1918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992344#comment-12992344
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Namit Jain commented on HIVE-1918:
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Reading from:
http://download.oracle.com/docs/cd/B10500_01/server.920/a96652/ch02.htm#1005081
Importing into Existing Tables
This section describes factors to take into account when you import data into
existing tables.
Manually Creating Tables Before Importing Data
When you choose to create tables manually before importing data into them from
an export file, you should use either the same table definition previously used
or a compatible format. For example, although you can increase the width of
columns and change their order, you cannot do the following:
Add NOT NULL columns
Change the datatype of a column to an incompatible datatype (LONG to NUMBER,
for example)
Change the definition of object types used in a table
Change DEFAULT column values
Note:
When tables are manually created before data is imported, the CREATE TABLE
statement in the export dump file will fail because the table already exists.
To avoid this failure and continue loading data into the table, set the import
parameter IGNORE=y. Otherwise, no data will be loaded into the table because of
the table creation error.
Do you want to support this ? Seems like a reasonable thing to have -
currently, an error is thrown during import
if the table already exists ?
> Add export/import facilities to the hive system
> -----------------------------------------------
>
> Key: HIVE-1918
> URL: https://issues.apache.org/jira/browse/HIVE-1918
> Project: Hive
> Issue Type: New Feature
> Components: Query Processor
> Reporter: Krishna Kumar
> Assignee: Krishna Kumar
> Attachments: HIVE-1918.patch.1.txt, HIVE-1918.patch.2.txt,
> HIVE-1918.patch.3.txt, HIVE-1918.patch.txt, hive-metastore-er.pdf
>
>
> This is an enhancement request to add export/import features to hive.
> With this language extension, the user can export the data of the table -
> which may be located in different hdfs locations in case of a partitioned
> table - as well as the metadata of the table into a specified output
> location. This output location can then be moved over to another different
> hadoop/hive instance and imported there.
> This should work independent of the source and target metastore dbms used;
> for instance, between derby and mysql.
> For partitioned tables, the ability to export/import a subset of the
> partition must be supported.
> Howl will add more features on top of this: The ability to create/use the
> exported data even in the absence of hive, using MR or Pig. Please see
> http://wiki.apache.org/pig/Howl/HowlImportExport for these details.
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