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From Reynold Xin <r...@databricks.com>
Subject Re: JDBC Dialect for saving DataFrame into Vertica Table
Date Thu, 26 May 2016 22:11:40 GMT
It's probably a good idea to have the vertica dialect too, since it doesn't
seem like it'd be too difficult to maintain. It is not going to be as
performant as the native Vertica data source, but is going to be much
lighter weight.


On Thu, May 26, 2016 at 3:09 PM, Mohammed Guller <mohammed@glassbeam.com>
wrote:

> Vertica also provides a Spark connector. It was not GA the last time I
> looked at it, but available on the Vertica community site. Have you tried
> using the Vertica Spark connector instead of the JDBC driver?
>
>
>
> Mohammed
>
> Author: Big Data Analytics with Spark
> <http://www.amazon.com/Big-Data-Analytics-Spark-Practitioners/dp/1484209656/>
>
>
>
> *From:* Aaron Ilovici [mailto:ailovici@wayfair.com]
> *Sent:* Thursday, May 26, 2016 8:08 AM
> *To:* user@spark.apache.org; dev@spark.apache.org
> *Subject:* JDBC Dialect for saving DataFrame into Vertica Table
>
>
>
> I am attempting to write a DataFrame of Rows to Vertica via
> DataFrameWriter's jdbc function in the following manner:
>
>
>
> dataframe.write().mode(SaveMode.Append).jdbc(url, table, properties);
>
>
>
> This works when there are no NULL values in any of the Rows in my
> DataFrame. However, when there are rows, I get the following error:
>
>
>
> ERROR Executor: Exception in task 0.0 in stage 3.0 (TID 24)
>
> java.sql.SQLFeatureNotSupportedException: [Vertica][JDBC](10220) Driver
> not capable.
>
>     at com.vertica.exceptions.ExceptionConverter.toSQLException(Unknown
> Source)
>
>     at
> com.vertica.jdbc.common.SPreparedStatement.checkTypeSupported(Unknown
> Source)
>
>     at com.vertica.jdbc.common.SPreparedStatement.setNull(Unknown Source)
>
>
>
> This appears to be Spark's attempt to set a null value in a
> PreparedStatement, but Vertica does not understand the type upon executing
> the transaction. I see in JdbcDialects.scala that there are dialects for
> MySQL, Postgres, DB2, MsSQLServer, Derby, and Oracle.
>
>
>
> 1 - Would writing a dialect for Vertica eleviate the issue, by setting a
> 'NULL' in a type that Vertica would understand?
>
> 2 - What would be the best way to do this without a Spark patch? Scala,
> Java, make a jar and call 'JdbcDialects.registerDialect(VerticaDialect)'
> once created?
>
> 3 - Where would one find the proper mapping between Spark DataTypes and
> Vertica DataTypes? I don't see 'NULL' handling for any of the dialects,
> only the base case 'case _ => None' - is None mapped to the proper NULL
> type elsewhere?
>
>
>
> My environment: Spark 1.6, Vertica Driver 7.2.2, Java 1.7
>
>
>
> I would be happy to create a Jira and submit a pull request with the
> VerticaDialect once I figure this out.
>
>
>
> Thank you for any insight on this,
>
>
>
> *AARON ILOVICI*
> Software Engineer
>
> Marketing Engineering
>
> *WAYFAIR*
> 4 Copley Place
> Boston, MA 02116
>
> (617) 532-6100 x1231
> ailovici@wayfair.com
>
>
>

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