It kind of already is. I was able to build the VerticaDialect as a sort of
plugin as follows:
Check out apache/spark tree
Copy in VerticaDialect.scala
Build with “mvn -DskipTests compile”
package the compiled class plus companion object into a JAR
Copy JAR to jars folder in Spark binary installation (optional, probably can
set path in an extra --jars argument instead)
Then run the following test in spark-shell after creating Vertica table and
sample data:
org.apache.spark.sql.jdbc.JdbcDialects.registerDialect(org.apache.spark.sql.jdbc.VerticaDialect)
val jdbcDF = spark.read.format("jdbc").option("url",
"jdbc:vertica://hpbox:5433/docker").option("dbtable",
"test_alltypes").option("user", "dbadmin").option("password",
"Vertica1!").load()
jdbcDF.show()
jdbcDF.write.mode("append").format("jdbc").option("url",
"jdbc:vertica://hpbox:5433/docker").option("dbtable",
"test_alltypes").option("user", "dbadmin").option("password",
"Vertica1!").save()
JdbcDialects.unregisterDialect(org.apache.spark.sql.jdbc.VerticaDialect)
If it would be preferable to write documentation describing the above, I can do
that instead. The hard part is checking out the matching apache/spark tree
then copying to the Spark cluster – I can install master branch and latest
binary and apply patches since I have root on all my test boxes, but customers
may not be able to. Still, this provides another route to support new JDBC
dialects.
BryanH
From: Wenchen Fan [mailto:cloud0...@gmail.com]
Sent: Wednesday, December 11, 2019 10:48 AM
To: Xiao Li <lix...@databricks.com>
Cc: Bryan Herger <bryan.her...@microfocus.com>; Sean Owen <sro...@gmail.com>;
dev@spark.apache.org
Subject: Re: I would like to add JDBCDialect to support Vertica database
Can we make the JDBCDialect a public API that users can plugin? It looks like
an end-less job to make sure Spark JDBC source supports all databases.
On Wed, Dec 11, 2019 at 11:41 PM Xiao Li
<lix...@databricks.com<mailto:lix...@databricks.com>> wrote:
You can follow how we test the other JDBC dialects. All JDBC dialects require
the docker integration tests.
https://github.com/apache/spark/tree/master/external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc
On Wed, Dec 11, 2019 at 7:33 AM Bryan Herger
<bryan.her...@microfocus.com<mailto:bryan.her...@microfocus.com>> wrote:
Hi, to answer both questions raised:
Though Vertica is derived from Postgres, Vertica does not recognize type names
TEXT, NVARCHAR, BYTEA, ARRAY, and also handles DATETIME differently enough to
cause issues. The major changes are to use type names and date format
supported by Vertica.
For testing, I have a SQL script plus Scala and PySpark scripts, but these
require a Vertica database to connect, so automated testing on a build server
wouldn’t work. It’s possible to include my test scripts and directions to run
manually, but not sure where in the repo that would go. If automated testing
is required, I can ask our engineers whether there exists something like a
mockito that could be included.
Thanks, Bryan H
From: Xiao Li [mailto:lix...@databricks.com<mailto:lix...@databricks.com>]
Sent: Wednesday, December 11, 2019 10:13 AM
To: Sean Owen <sro...@gmail.com<mailto:sro...@gmail.com>>
Cc: Bryan Herger
<bryan.her...@microfocus.com<mailto:bryan.her...@microfocus.com>>;
dev@spark.apache.org<mailto:dev@spark.apache.org>
Subject: Re: I would like to add JDBCDialect to support Vertica database
How can the dev community test it?
Xiao
On Wed, Dec 11, 2019 at 6:52 AM Sean Owen
<sro...@gmail.com<mailto:sro...@gmail.com>> wrote:
It's probably OK, IMHO. The overhead of another dialect is small. Are
there differences that require a new dialect? I assume so and might
just be useful to summarize them if you open a PR.
On Tue, Dec 10, 2019 at 7:14 AM Bryan Herger
<bryan.her...@microfocus.com<mailto:bryan.her...@microfocus.com>> wrote:
>
> Hi, I am a Vertica support engineer, and we have open support requests around
> NULL values and SQL type conversion with DataFrame read/write over JDBC when
> connecting to a Vertica database. The stack traces point to issues with the
> generic JDBCDialect in Spark-SQL.
>
> I saw that other vendors (Teradata, DB2...) have contributed a JDBCDialect
> class to address JDBC compatibility, so I wrote up a dialect for Vertica.
>
> The changeset is on my fork of apache/spark at
> https://github.com/bryanherger/spark/commit/84d3014e4ead18146147cf299e8996c5c56b377d
>
> I have tested this against Vertica 9.3 and found that this changeset
> addresses both issues reported to us (issue with NULL values - setNull() -
> for valid java.sql.Types, and String to VARCHAR conversion)
>
> Is the an acceptable change? If so, how should I go about submitting a pull
> request?
>
> Thanks, Bryan Herger
> Vertica Solution Engineer
>
>
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