Issue when using PySpark with Impala via JDBC

[#1]

Due to data masking, I can't read tables directly using 'vanilla' Spark. The workaround is connecting Spark to Impala via JDBC and the problem is: when I use reserved words or some operations like `+ INTERVAL 1 DAY` Impala returns the column names as values in the DataFrame.

That's how I start the Spark session:

spark = (
    SparkSession
    .builder
    .config("spark.jars", "/home/cdsw/ImpalaJDBC42.jar")
    .getOrCreate()
)

and how I query data:

(
    spark
    .read
    .format("jdbc")
    .option("driver", "com.cloudera.impala.jdbc.Driver")
    .option("url", "jdbc:impala://MY_IMPALA_HOST:443/default;AuthMech=3;transportMode=http;httpPath=cliservice;ssl=1")
    .option("PWD", "MY_PASSWORD")
    .option("UID", "MY_USERNAME")
    .option("query", "SELECT 'a' AS index FROM MY_TABLE")
    .load()
    .show()
)

That's what I get:

+-----+
|index|
+-----+
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
|index|
+-----+

Other errors are derived from this one. For example, when running the query:

SELECT current_date() + interval 1 day FROM MY_TABLE

raises the exception:

java.sql.SQLDataException: [Cloudera][JDBC](10140) Error converting value to Date.

This happens because Spark is expecting a date to be parsed but Impala returns the column name as a value. We can see the returned value by casting to string:

SELECT CAST(current_date() + interval 1 day AS STRING) FROM MY_TABLE

+-----------------------------------------------+
|cast(current_date() + interval 1 day as string)|
+-----------------------------------------------+
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
|                           cast(current_date...|
+-----------------------------------------------+

Can someone help me? I searched for a while and found some people facing this issue some years ago. Is there a solution already?

[#2]

@leoeiji Welcome to the Cloudera Community!

To help you get the best possible solution, I have tagged our Impala experts @jAnshula @Saurabhatiyal  who may be able to assist you further.

Please keep us updated on your post, and we hope you find a satisfactory solution to your query.

[#3 · Accepted solution]

Hello-

Pasting here the reply from 6 yrs ago, which I still find relevant:

Running Impala query over driver from Spark is not currently supported by Cloudera. Why don't you just use SparkSQL instead? Why need to have extra layer of impala here?

[#4]

@Boris G, I literaly started my thread explaining why I need Impala. Problem solved by the way.