用Cassandra中的一组值准备语句
我正在使用datastax Cassandra 2.0驱动程序,我正在使用准备好的和绑定的语句。假设我想询问这样的问题:用Cassandra中的一组值准备语句,cassandra,cql,cql3,datastax-java-driver,Cassandra,Cql,Cql3,Datastax Java Driver,我正在使用datastax Cassandra 2.0驱动程序,我正在使用准备好的和绑定的语句。假设我想询问这样的问题: SELECT * FROM foo WHERE mykey IN (UUID1, UUID2, UUID3); 其中UUID1、UUID2、UUID3是UUID值。使用绑定语句的编程方式是什么。目前,我正在尝试以下几点: preparedStatement = session.prepare("SELECT * FROM foo WHERE vref IN ?") boun
SELECT * FROM foo WHERE mykey IN (UUID1, UUID2, UUID3);
其中UUID1、UUID2、UUID3是UUID值。使用绑定语句的编程方式是什么。目前,我正在尝试以下几点:
preparedStatement = session.prepare("SELECT * FROM foo WHERE vref IN ?")
boundStatement = new BoundStatement(preparedStatement)
val uuids: java.util.ArrayList[java.util.UUID] = //assume we're getting the values from somewhere
session.execute(boundStatement.bind(uuids))
这当前返回了错误的结果。有没有关于如何正确设置查询格式的建议?下面是一个使用简单表格和文本值的示例。使用Centos 6.5和DSE4.5.1 我的桌子:
DESCRIBE TABLE deleteme1 ;
CREATE TABLE deleteme1 (
col1 text,
col2 text,
PRIMARY KEY ((col1))
) WITH
bloom_filter_fp_chance=0.010000 AND
caching='KEYS_ONLY' AND
comment='' AND
dclocal_read_repair_chance=0.100000 AND
gc_grace_seconds=10000 AND
index_interval=128 AND
read_repair_chance=0.000000 AND
replicate_on_write='true' AND
populate_io_cache_on_flush='false' AND
default_time_to_live=0 AND
speculative_retry='99.0PERCENTILE' AND
memtable_flush_period_in_ms=0 AND
compaction={'class': 'SizeTieredCompactionStrategy'} AND
compression={'sstable_compression': 'LZ4Compressor'};
我的数据:
cqlsh:results> select * from deleteme1 ;
col1 | col2
-------+-------
three | three
one | one
two | two
four | four
(4 rows)
我的样本测试类
import java.util.ArrayList;
import com.datastax.driver.core.BoundStatement;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;
public class PrepStatement {
Cluster cluster;
Session session;
public static void main(String args []){
PrepStatement myTest = new PrepStatement();
String node = "192.168.56.22";
myTest.runTest(node);
myTest.close();
}
private void runTest(String node){
ArrayList<String> vals = new ArrayList<String>(2);
vals.add("one");
vals.add("three");
try {
cluster = Cluster.builder()
.addContactPoint(node)
//.withCredentials("cassandra", "cassandra") // only if you need a login
.build();
session = cluster.connect();
PreparedStatement preparedStatement = session.prepare("SELECT * FROM results.deleteme1 WHERE col1 IN ?");
BoundStatement boundStatement = new BoundStatement(preparedStatement);
ResultSet results = session.execute(boundStatement.bind(vals));
for (Object result : results){
System.out.println(result.toString());
}
}
catch (Exception e){
e.printStackTrace();
}
}
/**
* cleans up the session
*/
private void close() {
session.close();
cluster.close();
}
}
注意:您只能对CQL3.0文档中概述的主键列使用IN查询:我刚刚查看了一些相关来源,您的方法似乎是正确的。你得到了什么样的错误结果?如果返回的行不正确,则可能是错误。如果您收到一个异常,则需要查看它,可能需要调整一些语法细节。请记住在中使用
。您不希望在生产集群中使用它:
Row[one, one]
Row[three, three]