docs(samples): add query external bigtable using temp table

samples/snippets/src/main/java/com/example/bigquery/QueryExternalBigtableTemp.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.bigquery;
+
+// [START bigquery_query_external_bigtable_temp]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.BigtableColumn;
+import com.google.cloud.bigquery.BigtableColumnFamily;
+import com.google.cloud.bigquery.BigtableOptions;
+import com.google.cloud.bigquery.ExternalTableDefinition;
+import com.google.cloud.bigquery.QueryJobConfiguration;
+import com.google.cloud.bigquery.TableResult;
+import com.google.common.collect.ImmutableList;
+import org.apache.commons.codec.binary.Base64;
+
+// Sample to queries an external bigtable data source using a temporary table
+public class QueryExternalBigtableTemp {
+
+  public static void main(String[] args) {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "MY_PROJECT_ID";
+    String instanceId = "MY_INSTANCE_ID";
+    String bigtableName = "MY_BIGTABLE_NAME";
+    String tableName = "MY_TABLE_NAME";
+    String sourceUri =
+        "https://googleapis.com/bigtable/projects/"
+            + projectId
+            + "/instances/"
+            + instanceId
+            + "/tables/"
+            + bigtableName;
+    String query = String.format("SELECT * FROM %s ", tableName);
+    queryExternalBigtableTemp(tableName, sourceUri, query);
+  }
+
+  public static void queryExternalBigtableTemp(String tableName, String sourceUri, String query) {
+    try {
+      // Initialize client that will be used to send requests. This client only needs to be created
+      // once, and can be reused for multiple requests.
+      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();
+
+      BigtableColumn name =
+          BigtableColumn.newBuilder()
+              .setQualifierEncoded(Base64.encodeBase64String("name".getBytes()))
+              .setFieldName("name")
+              .setType("STRING")
+              .setEncoding("TEXT")
+              .build();
+      BigtableColumn postAbbr =
+          BigtableColumn.newBuilder()
+              .setQualifierEncoded(Base64.encodeBase64String("post_abbr".getBytes()))
+              .setFieldName("post_abbr")
+              .setType("STRING")
+              .setEncoding("TEXT")
+              .build();
+      BigtableColumnFamily usStates =
+          BigtableColumnFamily.newBuilder()
+              .setColumns(ImmutableList.of(name, postAbbr))
+              .setFamilyID("us-states")
+              .setOnlyReadLatest(true)
+              .setEncoding("TEXT")
+              .setType("STRING")
+              .build();
+
+      // Configure BigtableOptions is optional.
+      BigtableOptions options =
+          BigtableOptions.newBuilder()
+              .setIgnoreUnspecifiedColumnFamilies(true)
+              .setReadRowkeyAsString(true)
+              .setColumnFamilies(ImmutableList.of(usStates))
+              .build();
+
+      // Configure the external data source and query job.
+      ExternalTableDefinition externalTable =
+          ExternalTableDefinition.newBuilder(sourceUri, options).build();
+      QueryJobConfiguration queryConfig =
+          QueryJobConfiguration.newBuilder(query)
+              .addTableDefinition(tableName, externalTable)
+              .build();
+
+      // Example query to find states starting with 'A'
+      TableResult results = bigquery.query(queryConfig);
+
+      results
+          .iterateAll()
+          .forEach(row -> row.forEach(val -> System.out.printf("%s,", val.toString())));
+
+      System.out.println("Query on external temporary table performed successfully.");
+    } catch (BigQueryException | InterruptedException e) {
+      System.out.println("Query not performed \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_query_external_bigtable_temp]

samples/snippets/src/test/java/com/example/bigquery/QueryExternalBigtableTempIT.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.bigquery;
+
+import static com.google.common.truth.Truth.assertThat;
+import static junit.framework.TestCase.assertNotNull;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.UUID;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class QueryExternalBigtableTempIT {
+
+  private final Logger log = Logger.getLogger(this.getClass().getName());
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+  private PrintStream originalPrintStream;
+
+  private static final String BIGTABLE_URI = requireEnvVar("BIGTABLE_URI");
+
+  private static String requireEnvVar(String varName) {
+    String value = System.getenv(varName);
+    assertNotNull(
+        "Environment variable " + varName + " is required to perform these tests.",
+        System.getenv(varName));
+    return value;
+  }
+
+  @BeforeClass
+  public static void checkRequirements() {
+    requireEnvVar("BIGTABLE_URI");
+  }
+
+  @Before
+  public void setUp() {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    originalPrintStream = System.out;
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    // restores print statements in the original method
+    System.out.flush();
+    System.setOut(originalPrintStream);
+    log.log(Level.INFO, bout.toString());
+  }
+
+  @Test
+  public void testQueryExternalBigtableTemp() {
+    String tableName =
+        "EXTERNAL_TEMP_TABLE_FROM_BIGTABLE_TEST_" + UUID.randomUUID().toString().substring(0, 8);
+    String query = String.format("SELECT * FROM %s ", tableName);
+    QueryExternalBigtableTemp.queryExternalBigtableTemp(tableName, BIGTABLE_URI, query);
+    assertThat(bout.toString())
+        .contains("Query on external temporary table performed successfully.");
+  }
+}