Allow 'game' examples to append to existing BigQuery tables.

----Release Notes----

[]
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=112915940

Author: jeffgardner

examples/src/main/java8/com/google/cloud/dataflow/examples/complete/game/utils/WriteToBigQuery.java

@@ -24,6 +24,7 @@
 import com.google.cloud.dataflow.sdk.Pipeline;
 import com.google.cloud.dataflow.sdk.io.BigQueryIO;
 import com.google.cloud.dataflow.sdk.io.BigQueryIO.Write.CreateDisposition;
+import com.google.cloud.dataflow.sdk.io.BigQueryIO.Write.WriteDisposition;
 import com.google.cloud.dataflow.sdk.options.GcpOptions;
 import com.google.cloud.dataflow.sdk.options.PipelineOptions;
 import com.google.cloud.dataflow.sdk.transforms.DoFn;
@@ -117,7 +118,8 @@ public PDone apply(PCollection<T> teamAndScore) {
                 .to(getTable(teamAndScore.getPipeline(),
                     tableName))
                 .withSchema(getSchema())
-                .withCreateDisposition(CreateDisposition.CREATE_IF_NEEDED));
+                .withCreateDisposition(CreateDisposition.CREATE_IF_NEEDED)
+                .withWriteDisposition(WriteDisposition.WRITE_APPEND));
   }
 
   /** Utility to construct an output table reference. */

examples/src/main/java8/com/google/cloud/dataflow/examples/complete/game/utils/WriteWindowedToBigQuery.java

@@ -19,6 +19,7 @@
 import com.google.api.services.bigquery.model.TableRow;
 import com.google.cloud.dataflow.sdk.io.BigQueryIO;
 import com.google.cloud.dataflow.sdk.io.BigQueryIO.Write.CreateDisposition;
+import com.google.cloud.dataflow.sdk.io.BigQueryIO.Write.WriteDisposition;
 import com.google.cloud.dataflow.sdk.transforms.DoFn;
 import com.google.cloud.dataflow.sdk.transforms.DoFn.RequiresWindowAccess;
 import com.google.cloud.dataflow.sdk.transforms.ParDo;
@@ -68,7 +69,8 @@ public PDone apply(PCollection<T> teamAndScore) {
                 .to(getTable(teamAndScore.getPipeline(),
                     tableName))
                 .withSchema(getSchema())
-                .withCreateDisposition(CreateDisposition.CREATE_IF_NEEDED));
+                .withCreateDisposition(CreateDisposition.CREATE_IF_NEEDED)
+                .withWriteDisposition(WriteDisposition.WRITE_APPEND));
   }
 
 }