[teiid-issues] [JBoss JIRA] (TEIID-3429) Provide hooks to interrogate metadata prior to full import

[Steven Hawkins (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-3429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13064601#comment-13064601 ] 

Steven Hawkins commented on TEIID-3429:
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> I guess, you are thinking to expose as procedures, then they can be called using the jdbc interface.

Any interface yes.  Even the execute-query admin operation.

> My concern there is there is two ways we providing the exposure to the source metadata, one through "getSchema" method on admin API and through JDBC. It would be nice to provide single way.

A couple of things.  First is that DDL is not appropriate for this.  As mentioned in the description it doesn't make sense to send back partial DDL. The next is that it seems clearer to expose the source view of metadata rather than the Teiid view - as that is more idiomatic to the import process.  So these procedures would return values that represent source structure - source table name, schema, and catalog for jdbc rather than just a name in source.  Lastly the admin logic is somewhat of a one off - there's a lot more overhead in adding new handlers, support (or not) for embedded, etc.  The only benefit I can see from using the admin would be to deploy the vdb with connection type none such that it's not generally accessible.  Alternatively over admin you could have something that takes a translator name, a jndi name, translator properties, etc. to not require a vdb.

> Yes, without that tools like designer will not have access to raw metadata. Also this needs to be on empty (vdb with metadata not loaded based on some flag, except for methods you mentioned above) vdb, which is pre-cursor to when you are ready to do the import with full "importer" properties that can get the actual metadata.

Just to make sure I'm not missing something, are you simply reiterating or do want to see something different about this flow?

> Provide hooks to interrogate metadata prior to full import 
> -----------------------------------------------------------
>
>                 Key: TEIID-3429
>                 URL: https://issues.jboss.org/browse/TEIID-3429
>             Project: Teiid
>          Issue Type: Feature Request
>          Components: Server
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>
> To support the Desinger we should offer the ability to interrogate metadata prior to full import.
> Exploring metadata is effectively an entirely different mode of operation with respect to the current metadata processing logic on the Teiid side.  Also partial metadata isn't something that would neatly be expressed through DDL - tables without columns, a list of schema names, etc.
> Ways around that would be to expose source procedures for metadata interrogation:
>  
> getTableNames - which would probably give both the Teiid name and the name in source and consider the current translator metadata settings
> getProcedureNames 
> And importer specific info such as for JDBC getTableTypes, getCatalogNames, getSchemaNames
>  
> I'd want to keep it fairly high level though.  Getting column or key information I'd expect would be done through the normal full import.



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