Use LOCAL_ONE when querying system.local

The system keyspace has a replication factor of 1 and is local to each
node; it is therefore recommended to query system.local with a
consistency level of ONE or LOCAL_ONE.

Stronger consistency levels may result in an Unavailable error, but this
does not mean that the node is down.

See gh-20709

Author: adutra

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/cassandra/CassandraHealthIndicator.java

@@ -16,9 +16,10 @@
 
 package org.springframework.boot.actuate.cassandra;
 
+import com.datastax.driver.core.ConsistencyLevel;
 import com.datastax.driver.core.ResultSet;
-import com.datastax.driver.core.querybuilder.QueryBuilder;
-import com.datastax.driver.core.querybuilder.Select;
+import com.datastax.driver.core.SimpleStatement;
+import com.datastax.driver.core.Statement;
 
 import org.springframework.boot.actuate.health.AbstractHealthIndicator;
 import org.springframework.boot.actuate.health.Health;
@@ -35,6 +36,9 @@
  */
 public class CassandraHealthIndicator extends AbstractHealthIndicator {
 
+	private static final Statement SELECT = new SimpleStatement("SELECT release_version FROM system.local")
+			.setConsistencyLevel(ConsistencyLevel.LOCAL_ONE);
+
 	private CassandraOperations cassandraOperations;
 
 	public CassandraHealthIndicator() {
@@ -53,9 +57,8 @@ public CassandraHealthIndicator(CassandraOperations cassandraOperations) {
 
 	@Override
 	protected void doHealthCheck(Health.Builder builder) throws Exception {
-		Select select = QueryBuilder.select("release_version").from("system", "local");
-		ResultSet results = this.cassandraOperations.getCqlOperations().queryForResultSet(select);
-		if (results.isExhausted()) {
+		ResultSet results = this.cassandraOperations.getCqlOperations().queryForResultSet(SELECT);
+		if (results.isFullyFetched()) {
 			builder.up();
 			return;
 		}