Bug: SparkSessionBuilder shoud not propagate static sql configurations to the existing active/default SparkSession
Status: Resolved | Priority: Major | Resolution: Fixed
Created: 23/Apr/20 15:50
Affects Version/s: 2.0.2

Clearly, this is a bug.
{code:java}
scala> spark.sql("set spark.sql.warehouse.dir").show
+--------------------+--------------------+
|                 key|               value|
+--------------------+--------------------+
|spark.sql.warehou...|file:/Users/kenty...|
+--------------------+--------------------+


scala> spark.sql("set spark.sql.warehouse.dir=2");
org.apache.spark.sql.AnalysisException: Cannot modify the value of a static config: spark.sql.warehouse.dir;
  at org.apache.spark.sql.RuntimeConfig.requireNonStaticConf(RuntimeConfig.scala:154)
  at org.apache.spark.sql.RuntimeConfig.set(RuntimeConfig.scala:42)
  at org.apache.spark.sql.execution.command.SetCommand.$anonfun$x$7$6(SetCommand.scala:100)
  at org.apache.spark.sql.execution.command.SetCommand.run(SetCommand.scala:156)
  at org.apache.spark.sql.execution.command.ExecutedCommandExec.sideEffectResult$lzycompute(commands.scala:70)
  at org.apache.spark.sql.execution.command.ExecutedCommandExec.sideEffectResult(commands.scala:68)
  at org.apache.spark.sql.execution.command.ExecutedCommandExec.executeCollect(commands.scala:79)
  at org.apache.spark.sql.Dataset.$anonfun$logicalPlan$1(Dataset.scala:229)
  at org.apache.spark.sql.Dataset.$anonfun$withAction$1(Dataset.scala:3644)
  at org.apache.spark.sql.execution.SQLExecution$.$anonfun$withNewExecutionId$5(SQLExecution.scala:103)
  at org.apache.spark.sql.execution.SQLExecution$.withSQLConfPropagated(SQLExecution.scala:163)
  at org.apache.spark.sql.execution.SQLExecution$.$anonfun$withNewExecutionId$1(SQLExecution.scala:90)
  at org.apache.spark.sql.SparkSession.withActive(SparkSession.scala:764)
  at org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:64)
  at org.apache.spark.sql.Dataset.withAction(Dataset.scala:3642)
  at org.apache.spark.sql.Dataset.<init>(Dataset.scala:229)
  at org.apache.spark.sql.Dataset$.$anonfun$ofRows$2(Dataset.scala:100)
  at org.apache.spark.sql.SparkSession.withActive(SparkSession.scala:764)
  at org.apache.spark.sql.Dataset$.ofRows(Dataset.scala:97)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$1(SparkSession.scala:607)
  at org.apache.spark.sql.SparkSession.withActive(SparkSession.scala:764)
  at org.apache.spark.sql.SparkSession.sql(SparkSession.scala:602)
  ... 47 elided

scala> import org.apache.spark.sql.SparkSession
import org.apache.spark.sql.SparkSession

scala> SparkSession.builder.config("spark.sql.warehouse.dir", "xyz").get
getClass   getOrCreate

scala> SparkSession.builder.config("spark.sql.warehouse.dir", "xyz").getOrCreate
20/04/23 23:49:13 WARN SparkSession$Builder: Using an existing SparkSession; some configuration may not take effect.
res7: org.apache.spark.sql.SparkSession = org.apache.spark.sql.SparkSession@6403d574

scala> spark.sql("set spark.sql.warehouse.dir").show
+--------------------+-----+
|                 key|value|
+--------------------+-----+
|spark.sql.warehou...|  xyz|
+--------------------+-----+


scala>
{code}