jamisonbennett commented on a change in pull request #23398: [SPARK-26493][SQL]
Allow multiple spark.sql.extensions
URL: https://github.com/apache/spark/pull/23398#discussion_r244414275
##########
File path:
sql/core/src/test/scala/org/apache/spark/sql/SparkSessionExtensionSuite.scala
##########
@@ -114,6 +124,25 @@ class SparkSessionExtensionSuite extends SparkFunSuite {
stop(session)
}
}
+
+ test("use multiple custom class for extensions") {
+ val session = SparkSession.builder()
+ .master("local[1]")
+ .config("spark.sql.extensions", Seq(
+ classOf[MyExtensions].getCanonicalName,
+ classOf[MyExtensions2].getCanonicalName).mkString(","))
+ .getOrCreate()
+ try {
+
assert(session.sessionState.planner.strategies.contains(MySparkStrategy(session)))
+
assert(session.sessionState.analyzer.extendedResolutionRules.contains(MyRule(session)))
+ assert(session.sessionState.functionRegistry
+ .lookupFunction(MyExtensions.myFunction._1).isDefined)
+ assert(session.sessionState.functionRegistry
+ .lookupFunction(MyExtensions2.myFunction._1).isDefined)
Review comment:
Prior to this change, it was possible to programmatically register multiple
extensions but it was not possible to do so through the spark.sql.extensions
configuration. Although it wasn't documented/tested until this pull request.
E.g. The following works without this pull request:
```
SparkSession.builder()
.master("..")
.withExtensions(sparkSessionExtensions1)
.withExtensions(sparkSessionExtensions2)
.getOrCreate()
```
So I think conflicting function names are already currently possible (but
not documented). In the following cases:
1. Conflicting function names are registered by calling `.withExtenions()`
multiple times
2. An extension accidentally registers a function that was already
registered with the builtin functions
3. An extension accidentally registers a function multiple times by calling
`injectFunction(myFunction)`
As for the order, it looks to me like the last function to be stored with
conflicting names is the one which is retrieved:
```
class SimpleFunctionRegistry extends FunctionRegistry {
@GuardedBy("this")
private val functionBuilders =
new mutable.HashMap[FunctionIdentifier, (ExpressionInfo,
FunctionBuilder)]
override def registerFunction(
name: FunctionIdentifier,
info: ExpressionInfo,
builder: FunctionBuilder): Unit = synchronized {
functionBuilders.put(normalizeFuncName(name), (info, builder))
}
```
I will update this PR to document what happens in order of operations and
conflicts. If we need to explicitly block duplicates functions from being
registered, I can temporarily drop this PR and see about making those changes
first.
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