Differences between Spark SQL and Databricks

[dollyb]

Hello,

I'm using a local Docker Spark 3.5 runtime to test my Databricks Connect code. However I've come across a couple of cases where my code would work in one environment, but not the other.

Concrete example, I'm reading data from BigQuery via spark.read.format("bigquery") and the BigQuery connector 0.36.1 in my local environment. I can't seem to find out what library Databricks is using.

So when I fetch a table, the dataset has a subtly different schema which I don't understand since the table is the same.

Spark:

 |-- event_params: map (nullable = false)
 |    |-- key: string
 |    |-- value: struct (valueContainsNull = true)
 |    |    |-- string_value: string (nullable = true)
 |    |    |-- int_value: long (nullable = true)
 |    |    |-- float_value: double (nullable = true)
 |    |    |-- double_value: double (nullable = true)

Databricks

|-- event_params: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- key: string (nullable = true)
 |    |    |-- value: struct (nullable = true)
 |    |    |    |-- string_value: string (nullable = true)
 |    |    |    |-- int_value: long (nullable = true)
 |    |    |    |-- float_value: double (nullable = true)
 |    |    |    |-- double_value: double (nullable = true)

So in Databricks, it's wrapped in an extra array which makes no sense to me.

What library is Databricks using? How to handle these differences in environments?

When adding my local dependency, I get this:

Multiple sources found for bigquery (com.google.cloud.spark.bigquery.BigQueryRelationProvider, com.google.cloud.spark.bigquery.v2.Spark35BigQueryTableProvider)

[daniel_sahal]

@dollyb 
That's because when you've added another dependency on Databricks, it doesn't really know which one it should use. By default it's using built-in com.google.cloud.spark.bigquery.BigQueryRelationProvider.

What you can do is provide whole package name into format(), ex.

spark.read.format("com.google.cloud.spark.bigquery.v2.Spark35BigQueryTableProvider")