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https://issues.apache.org/jira/browse/DRILL-3180?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14701776#comment-14701776
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Magnus Pierre commented on DRILL-3180:
--------------------------------------
Some findings:
The plugin is much improved, but I found some issues that might be looked at:
Metadata for tables only available if URL does not contain target database and
only contain the path to the server. (MYSQL) - This is not how it need to work
since it excludes many databases such as Netezza that demands to have a target
database as part of the URL. (at least when I tried them)
I personally do not think it is a good idea to have the connection to the
database as part of the constructor method for the plugin. It is not possible
to create a plugin statement in drill for a db that is not online, even though
the information is valid. One alternative is to actually check enabled or not
in the json before deciding to connect to db.
The constructor need to throw the correct error message in case of valid json
but invalid connection otherwise it will be hard to understand where the real
problem lies.
SHOW TABLES does not work for schemas returned from JDBC plugin.
Join pushdown works for simple constructs such as:
select * from
mp.employees.`employees` e
INNER JOIN
mp.employees.`salaries` s
ON e.`EMP_NO` = s.`EMP_NO`
WHERE s.`to_date` > CURRENT_DATE
But is not happening when writing it as:
select * from
mp.employees.`employees` e
INNER JOIN
mp.employees.`salaries` s
ON e.`EMP_NO` = s.`EMP_NO`
AND s.`to_date` > CURRENT_DATE
Which is quite common-place.
A more complex query:
select * from
mp.employees.`employees` e
INNER JOIN
mp.employees.`salaries` s
ON e.`EMP_NO` = s.`EMP_NO`
INNER JOIN
mp.employees.`dept_emp` ed
ON e.`EMP_NO` = ed.`EMP_NO`
WHERE s.`to_date` > CURRENT_DATE and ed.`to_date` > CURRENT_DATE
Fail with:
org.apache.drill.common.exceptions.UserRemoteException: SYSTEM ERROR:
IllegalStateException: Already had POJO for id (java.lang.Integer)
[com.fasterxml.jackson.annotation.ObjectIdGenerator$IdKey@3372bbe8] Fragment
1:0 [Error Id: b34092c2-9225-4e37-9955-3a28b6215d97 on
administorsmbp2.lan:31010]
I have not investigated it further.
> Apache Drill JDBC storage plugin to query rdbms systems such as MySQL and
> Netezza from Apache Drill
> ---------------------------------------------------------------------------------------------------
>
> Key: DRILL-3180
> URL: https://issues.apache.org/jira/browse/DRILL-3180
> Project: Apache Drill
> Issue Type: New Feature
> Components: Storage - Other
> Affects Versions: 1.0.0
> Reporter: Magnus Pierre
> Assignee: Jacques Nadeau
> Labels: Drill, JDBC, plugin
> Fix For: 1.2.0
>
> Attachments: patch.diff, pom.xml, storage-mpjdbc.zip
>
> Original Estimate: 1m
> Remaining Estimate: 1m
>
> I have developed the base code for a JDBC storage-plugin for Apache Drill.
> The code is primitive but consitutes a good starting point for further
> coding. Today it provides primitive support for SELECT against RDBMS with
> JDBC.
> The goal is to provide complete SELECT support against RDBMS with push down
> capabilities.
> Currently the code is using standard JDBC classes.
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