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https://issues.apache.org/jira/browse/SPARK-10868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15425598#comment-15425598
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Reynold Xin edited comment on SPARK-10868 at 8/17/16 11:32 PM:
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I'm going to close this. I don't think adding an offset will actually satisfy
the use case, due to how monotonically_increasing_id is implemented under the
hood.
Also the proposed implementation is equivalent to
{code}
offset + monotonically_increasing_id()
{code}
-- something the user can do trivially.
was (Author: rxin):
I'm going to close this. I don't think adding an offset will actually satisfy
the use case, due to how monotonically_increasing_id is implemented under the
hood.
Also the proposed implementation is equivalent to
{code}
offset + monotonically_increasing_id()
{code}+
-- something the user can do trivially.
> monotonicallyIncreasingId() supports offset for indexing
> --------------------------------------------------------
>
> Key: SPARK-10868
> URL: https://issues.apache.org/jira/browse/SPARK-10868
> Project: Spark
> Issue Type: New Feature
> Components: SQL
> Affects Versions: 1.5.0
> Reporter: Martin Senne
>
> With SPARK-7135 and https://github.com/apache/spark/pull/5709
> `monotonicallyIncreasingID()` allows to create an index column with unique
> ids. The indexing always starts at 0 (no offset).
> *Feature wish*
> Having a parameter `offset`, such that the function can be used as
> {{monotonicallyIncreasingID( offset )}}
> and indexing _starts at *offset* instead of 0_.
> *Use-case*
> Add rows to a DataFrame that is already written to a DB (via
> _.write.jdbc(...)_).
> In detail:
> - A DataFrame *A* (containing an ID column) and having indices from 0 to 199
> in that column is existent in DB.
> - New rows need to be added to *A*. This included
> -- Creating a DataFrame *A'* with new rows, but without id column
> -- Add the index column to *A'* - this time starting at *200*, as there are
> already entries with id's from 0 to 199 (*here, monotonicallyInreasingID( 200
> ) is required.*)
> -- union *A* and *A'*
> -- store into DB
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