gaborgsomogyi commented on a change in pull request #24173: [SPARK-27237][SS]
Introduce State schema validation among query restart
URL: https://github.com/apache/spark/pull/24173#discussion_r268118336
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/state/StateStore.scala
##########
@@ -477,5 +486,82 @@ object StateStore extends Logging {
None
}
}
-}
+ private class StateSchemaCompatibilityChecker(
+ providerId: StateStoreProviderId,
+ hadoopConf: Configuration) {
+
+ private val storeCpLocation = providerId.storeId.storeCheckpointLocation()
+ private val fm = CheckpointFileManager.create(storeCpLocation, hadoopConf)
+ private val schemaFileLocation = schemaFile(storeCpLocation)
+
+ fm.mkdirs(schemaFileLocation.getParent)
+
+ def check(keySchema: StructType, valueSchema: StructType): Unit = {
+ if (fm.exists(schemaFileLocation)) {
+ logDebug(s"Schema file for provider $providerId exists. Comparing with
provided schema.")
+ val (storedKeySchema, storedValueSchema) = readSchemaFile()
+
+ def typesEq(schema1: StructType, schema2: StructType): Boolean = {
+ val fieldToType: StructField => (DataType, Boolean) = f =>
(f.dataType, f.nullable)
+ (schema1.length == schema2.length) &&
+ schema1.map(fieldToType).equals(schema2.map(fieldToType))
+ }
+
+ def namesEq(schema1: StructType, schema2: StructType): Boolean = {
+ schema1.fieldNames.toList.equals(schema2.fieldNames.toList)
+ }
+
+ val errorMsg = "Provided schema doesn't match to the schema for
existing state! " +
+ "Please note that Spark allow difference of field name: check count
of fields " +
+ "and data type of each field.\n" +
+ s"- provided schema: key $keySchema value $valueSchema\n" +
+ s"- existing schema: key $storedKeySchema value $storedValueSchema\n"
+
+ if (!typesEq(keySchema, storedKeySchema) || !typesEq(valueSchema,
storedValueSchema)) {
+ logError(errorMsg)
+ throw new IllegalStateException(errorMsg)
+ } else if (!namesEq(keySchema, storedKeySchema) ||
+ !namesEq(valueSchema, storedValueSchema)) {
+ logInfo("Detected the change of field name, will overwrite schema
file to new.")
Review comment:
Just for the sake of my understanding which use-case is this from user
perspective?
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