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https://issues.apache.org/jira/browse/TRAFODION-1586?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sandhya Sundaresan resolved TRAFODION-1586.
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Resolution: Fixed
> Add support to create an external Trafodion table and map it to a native
> HBase table
> ------------------------------------------------------------------------------------
>
> Key: TRAFODION-1586
> URL: https://issues.apache.org/jira/browse/TRAFODION-1586
> Project: Apache Trafodion
> Issue Type: New Feature
> Reporter: Anoop Sharma
> Assignee: Anoop Sharma
> Priority: Minor
>
> Proposal to create an external table in Trafodion metadata and map it to an
> existing HBase table.
> Listed below are proposed syntax and semantics rules for this support.
> Proposed Syntax:
> create external table T (…column definitions…) map to hbase table T;
> this will create a Trafodion table in metadata with columns specified
> in ‘column definitions’ and
> map that definition to an externally created native HBase table T.
> alter table T add column b;
> alter table T drop column b;
> will add and drop column ‘b’ from Trafodion metadata. Underlying mapped
> HBase table will not be affected.
> drop table T;
> will drop external table T from Trafodion metadata. Underlying mapped
> HBase table will not be affected.
> Semantics:
> If table T is specified in a DDL or DML statement without an explicit
> schema (like: drop table T, or select * from T
> ,or create table Tlike like T),
> then it will be first searched as a regular table in default regular schema.
> If not found, then it will be searched as a mapped table.
> So a regular table T will take precedence over a mapped table T.
> It is recommended that one does not create a regular table and a mapped
> table with the same name to avoid confusion.
> Restrictions:
> To limit the initial scope of this work, there will be some restrictions.
> Some of these may be lifted
> at a later time.
> insert, update and delete statements on mapped tables will not be
> initially supported.
> a mapped table cannot be aligned format table
> A primary key clause must be specified
> external and hbase mapped table names must be the same
> All non-primarykey and non-nullable columns must have a default value.
> This is needed to handle missing values
> in the underlying HBase table.
> creation of a Trafodion index on a mapped table will not be supported
> This proposal will be updated with additional syntax and semantics rules
> going forward.
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