Minor Description
DROP NAMESPACE IF EXISTS
{table}
if a catalog doesn't overrides `namespaceExists` it by default uses `loadNamespaceMetadata` and in case a `db` not exists loadNamespaceMetadata throws a `NoSuchDatabaseException` which is not catched and we see failures even with `if exists` clause. One such use case we observed was in iceberg table a post test clean up was failing with `NoSuchDatabaseException` now.
Found V2SessionCatalog `loadNamespaceMetadata` was also throwing the same unlike `JDBCTableCatalog`
ref a stack trace :
Database 'db' not found
org.apache.spark.sql.catalyst.analysis.NoSuchDatabaseException: Database 'db' not found
at org.apache.spark.sql.catalyst.catalog.SessionCatalog.requireDbExists(SessionCatalog.scala:219)
at org.apache.spark.sql.catalyst.catalog.SessionCatalog.getDatabaseMetadata(SessionCatalog.scala:284)
at org.apache.spark.sql.execution.datasources.v2.V2SessionCatalog.loadNamespaceMetadata(V2SessionCatalog.scala:247)
at org.apache.iceberg.spark.SparkSessionCatalog.loadNamespaceMetadata(SparkSessionCatalog.java:97)
at org.apache.spark.sql.connector.catalog.SupportsNamespaces.namespaceExists(SupportsNamespaces.java:98)
at org.apache.spark.sql.execution.datasources.v2.DropNamespaceExec.run(DropNamespaceExec.scala:40)
at org.apache.spark.sql.execution.datasources.v2.V2CommandExec.result$lzycompute(V2CommandExec.scala:43)
at org.apache.spark.sql.execution.datasources.v2.V2CommandExec.result(V2CommandExec.scala:43)
at org.apache.spark.sql.execution.datasources.v2.V2CommandExec.executeCollect(V2CommandExec.scala:49)
at org.apache.spark.sql.execution.QueryExecution$$anonfun$eagerlyExecuteCommands$1.$anonfun$applyOrElse$1(QueryExecution.scala:98)
