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https://issues.apache.org/jira/browse/TAJO-1359?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14533769#comment-14533769
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ASF GitHub Bot commented on TAJO-1359:
--------------------------------------
Github user jihoonson commented on the pull request:
https://github.com/apache/tajo/pull/422#issuecomment-100076808
Thanks. I've verified that join and aggregation queries work well. Really
nice patch.
The one thing I'd like to comment is that it needs to improve the error
message.
Here is an example case.
```
default> select title, name.first_name, name.last_name from test t1, test
t2 where t1.name.last_name = t2.name.last_name;
ERROR: column "title" does not exist
default> select name.first_name, name.last_name from test t1, test t2 where
t1.name.last_name = t2.name.last_name;
ERROR: column name name.first_name is ambiguous
```
It would be great if the ambiguous exception occurs for the first case.
---
Comments from the [review on
Reviewable.io](https://reviewable.io:443/reviews/apache/tajo/422)
<!-- Sent from Reviewable.io -->
> Add nested field projector and language extension to project nested record
> --------------------------------------------------------------------------
>
> Key: TAJO-1359
> URL: https://issues.apache.org/jira/browse/TAJO-1359
> Project: Tajo
> Issue Type: Sub-task
> Components: parser, physical operator, planner/optimizer
> Reporter: Hyunsik Choi
> Assignee: Hyunsik Choi
> Fix For: 0.11.0
>
> Attachments: TAJO-1359.patch, TAJO-1359_2.patch, TAJO-1359_3.patch,
> TAJO-1359_4.patch, TAJO-1359_5.patch, TAJO-1359_6.patch, TAJO-1359_7.patch,
> TAJO-1359_8.patch
>
>
> We need to improve Projector class to get nested record fields, and we also
> add some language extension to specify certain nested records in table
> schema. Both works should be done together. Otherwise, we need to test an
> entire work process.
> Using dot '.' would be good for the syntax to specify nested fields. Many
> systems (Hive, Google BigQuery, and Drill) already use this syntax. Probably,
> many users are familiar with this form.
> For example, if *employee* is a root nested record field and it includes
> *age* and *name* fields, consisting two fields lastname and firstname, we can
> specify them individually as follows:
> {code}
> SELECT employee.age, employee.name.lastname, employee.name.firstname FROM ...
> {code}
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