[英]Hbase Long Comparison Filter using Java Api
I am unable to compare a Long value in one of the column values of my HBase table. 我无法在我的HBase表的列值之一中比较Long值。 I am using java api. 我正在使用Java API。 Below is the code snippet.I clearly have a value in the table which satisfies the filter. 下面是代码片段。我显然在表格中有一个满足过滤条件的值。
I would also like to know what is lexicographical comparison and how would I perform long comparison. 我还想知道什么是词典比较以及如何进行长时间比较。
Any direction on this greatly helpful. 任何方向对此都大有帮助。
Thanks in advance 提前致谢
FilterList list = new FilterList(FilterList.Operator.MUST_PASS_ALL);
SingleColumnValueFilter fil = new SingleColumnValueFilter(CF1_BYTE, VALUE_BYTE, CompareOp.LESS,new BinaryComparator(Bytes.toBytes(50)));
Scan scan = new Scan();
scan.addColumn(Bytes.toBytes("C1"),Bytes.toBytes("VALUE"));
list.addFilter(fil);
scan.setFilter(list);
try {
ResultScanner scanner = table.getScanner(scan);
for(Result r : scanner){
String VAL = Bytes.toString(r.getValue(Bytes.toBytes("C1"),Bytes.toBytes("VALUE")));
count ++;
if(count == 1000){
break;
}
System.out.println(count +" "+Bytes.toString(r.getRow()) + " "+VAL );
}
scanner.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
table.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
According to doc , you have to provide your own comparator which will deserialize Long values from Byte arrays. 根据doc ,您必须提供自己的比较器,该比较器将从Byte数组中反序列化Long值。 As I know default comparison is lexicographical. 据我所知,默认比较是按字典顺序进行的。 Regarding lexicographical comparison, you can find this post useful. 关于词典比较,您可以找到这篇文章有用。 And this post provide a clue how you can write the corresponding comparator. 这篇文章提供了如何编写相应比较器的线索。
Update : 更新 :
import java.util.Comparator
import org.apache.hadoop.hbase.util.Bytes
class LongComparator implements Comparator<byte[]> {
public int compare(byte[] left, byte[] right) {
long leftLong = Bytes.toLong(left);
long rightLong = Bytes.toLong(right);
return Long.compare(leftLong, rightLong);
}
}
I suggest using HBase utils instead of guava since it may conflict with HBase guava dependencies. 我建议使用HBase utils代替guava,因为它可能与HBase guava依赖项冲突。
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