chenjunjiedada commented on a change in pull request #374: Migrate spark table
to iceberg table
URL: https://github.com/apache/incubator-iceberg/pull/374#discussion_r315174196
##########
File path: spark/src/main/scala/org/apache/iceberg/spark/SparkTableUtil.scala
##########
@@ -297,5 +301,88 @@ object SparkTableUtil {
)
}
}
+
+ def buildManifest(table: Table,
+ sparkDataFiles: Seq[SparkDataFile],
+ partitionSpec: PartitionSpec): ManifestFile = {
+ val outputFile = table.io
+ .newOutputFile(FileFormat.AVRO.addExtension("/tmp/" +
UUID.randomUUID.toString))
+ val writer = ManifestWriter.write(partitionSpec, outputFile)
+ try {
+ for (file <- sparkDataFiles) {
+ writer.add(file.toDataFile(partitionSpec))
+ }
+ } finally {
+ writer.close()
+ }
+
+ writer.toManifestFile
+ }
+
+ def partitionToMap(partition: String): Map[String, String] = {
+ val map = new mutable.HashMap[String, String]()
+ val list = partition.split("/")
+ list.foreach { str =>
+ val kv = str.split("=")
+ map.put(kv(0), kv(1))
+ }
+
+ map.toMap
+ }
+
+ /**
+ * Migrate a spark table to a iceberg table.
+ *
+ * The migration uses the spark session to get table metadata. It assumes no
+ * operation is going on original table and target table and thus is not
+ * thread-safe.
+ *
+ * @param dbName the database name of the table to be migrated
+ * @param tableName the table to be migrated
+ * @param table the target table to migrate in
+ *
+ * @return table the target table
+ */
+ def migrateSparkTable(dbName: String, tableName: String, table: Table):
Table = {
+ val sparkSession = SparkSession.builder().getOrCreate()
+
+ if (!sparkSession.catalog.tableExists(dbName, tableName)) {
+ throw new NoSuchTableException(s"Table $dbName.$tableName does not
exist")
+ }
+
+ val tableMetadata = sparkSession.sessionState.catalog.
Review comment:
It depends on whether the "replace pointer" action can happen on a managed
or external table. For a managed table, the table should be operated according
to iceberg metadata after migration. For an external table, I 'm not sure
whether we can replace the pointer, or whether we are allowed to replace the
pointer. In a real scenario, users may want to keep both of them, so we might
provide an option to delete the pointer if we can.
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