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https://issues.apache.org/jira/browse/GRIFFIN-332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17178717#comment-17178717
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Obaidul Karim edited comment on GRIFFIN-332 at 8/17/20, 4:45 AM:
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[~ishanverma]
on copy to s3, it is just an additional EMR Step to copy from HDFS to S3 using
[s3-dist-cp|https://docs.aws.amazon.com/emr/latest/ReleaseGuide/UsingEMR_s3distcp.html]
was (Author: obaid):
[~ishanverma]
on copy to s3, it is just an additional EMR Step using
[s3-dist-cp|https://docs.aws.amazon.com/emr/latest/ReleaseGuide/UsingEMR_s3distcp.html]
> JDBC Connector: Ability to Select Specific Columns Instead of All the Columns
> -----------------------------------------------------------------------------
>
> Key: GRIFFIN-332
> URL: https://issues.apache.org/jira/browse/GRIFFIN-332
> Project: Griffin
> Issue Type: Improvement
> Components: accuracy-batch
> Affects Versions: 0.6.0
> Reporter: Obaidul Karim
> Priority: Major
> Labels: columns, jdbc
>
> *Background:*
> Thanks to https://issues.apache.org/jira/browse/GRIFFIN-315, we already have
> JDBC connector.
> However, currently, it is pulling all the columns using`"SELECT * FROM
> $fullTableName"`.
> It will cause some issues for larger JDBC tables -
> - memory overhead for spark data frame
> - longer execution time
> - resource overhear for RDBMS
> *Proposed Improvement:*
> So, I propose the feature to allow JDBC connector to able to select only
> required columns.
> *Example:*
> We have a rule `"rule":"src.id = tgt.id and src.country = tgt.country "`.
> Then we only need two columns `id` and 'country'.
> So, in connector we can add additional clause `columns` to select only
> required columns, like below:
>
> {code:java}
> { "name":"src",
> "connector":{ "type":"jdbc",
> "config":{ "database":"mydatabase",
> "tablename":"mytable",
> "columns":"id, country",
> "url":"jdbc:sqlserver://myhost:1433;databaseName=mydatabase",
> "user":"user",
> "password":"password",
> "driver":"com.microsoft.sqlserver.jdbc.SQLServerDriver",
> "where":""
> }
> }
> }
> {code}
> We can implement it like this, if there is `columns` clause then use it
> otherwise use `*` as default.
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