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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-374) Enable access to dynamic columns in * or cf.* selection
Date Tue, 18 Dec 2018 02:11:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-374?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16723588#comment-16723588
] 

James Taylor commented on PHOENIX-374:
--------------------------------------

The client already embeds the column type where needed in the server calls it makes. For example,
in the filter pushed to the server, we transmit the data type as part of the expression information.

The trickiest part is maintaining the correct order of columns in a .SELECT * or SELECT cf.*.
The client will need to use the DatabaseMetaData APIs to get the ResultSetMetaData to know
how to interpret the data received back from the server. Any declared columns should appear
first followed by dynamic columns.

> Enable access to dynamic columns in * or cf.* selection
> -------------------------------------------------------
>
>                 Key: PHOENIX-374
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-374
>             Project: Phoenix
>          Issue Type: New Feature
>            Reporter: nicolas maillard
>            Assignee: Chinmay Kulkarni
>            Priority: Critical
>
> As of recent work we can now read and write columns that are not in the schema, AKA dynamic
columns. the Select and Upsert allow dynamic columns to be specified. 
> I think two additions are still needed.
> - Alter dynamicly: In the Upsert and/or Select statement  the ability to add on the specified
dynamic column to schema. Say Upsert into Table (key, cf.dynColumn varchar SCHEMAADD) values
(..)
> and for select: 
>      - select key, cf.dynColumn varchar from T would only read
>      - select key from T(cf.dynColumn varchar ) would only read and wrtie to schema
> - Select a complete column Family: More complex, accessing a whole Column Family with
all rows known in schema or not.
>  select cf.* from T
> today this works for know columns it could be nice to have this for all columns of a
family in the schema or not. I'm trying right now to extend this to schema for unknown columns.
However every new row can a lot of very different unknowcolumns. The defined ones will be
first but the unknown one will be appended at the end.
> This means the metadata might need to be updated at every row to account for all new
columns discovered.



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