[英]Hbase Java API: Retrieving all rows that match a Partial Row Key
In the Python module happybase , I can retrieve all rows that have a row key starting with a given string (ie, search using a partial row key). 在Python模块happybase中 ,我可以检索具有以给定字符串开头的行键的所有行(即,使用部分行键进行搜索)。
Let's say I have a rowkey in the format of (ID|TYPE|DATE), I would be able to find all rows with an ID of 1 and a TYPE of A by: 假设我有一个格式为(ID | TYPE | DATE)的rowkey,我可以通过以下方式找到ID为1且TYPE为A的所有行:
import happybase
connection = happybase.Connection('hmaster-host.com')
table = connection.table('table_name')
for key, data in table.scan(row_prefix="1|A|"):
print key, data
This is what I have so far as a totally client side Java program for anyone trying to do the basics using the Java HBase API , but I can only search for a row using the full row key: 到目前为止,这是一个完全客户端的Java程序,适用于任何尝试使用Java HBase API进行基础操作的人,但我只能使用完整的行键搜索一行:
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.util.Bytes;
//class foo {
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.addResource(new Path("C:\\core-site.xml"));
conf.addResource(new Path("C:\\hbase-site.xml"));
HTable table = new HTable(conf, "table_name");
Result row = table.get(new Get(Bytes.toBytes("1|A|2014-01-01 00:00")));
printRow(row);
}
public static void printRow(Result result) {
String returnString = "";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("id"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("type"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("date")));
System.out.println(returnString);
}
//}
Where "cf" is the name of the column family. 其中“cf”是列族的名称。
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.PrefixFilter;
import org.apache.hadoop.hbase.util.Bytes;
//class foo {
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.addResource(new Path("C:\\core-site.xml"));
conf.addResource(new Path("C:\\hbase-site.xml"));
HTable table = new HTable(conf, "table_name");
byte[] prefix = Bytes.toBytes("1|A|");
Scan scan = new Scan(prefix);
Filter prefixFilter = new PrefixFilter(prefix);
scan.setFilter(prefixFilter);
ResultScanner resultScanner = table.getScanner(scan);
printRows(resultScanner);
//Result row = table.get(new Get(Bytes.toBytes("1|A|2014-01-01 00:00")));
//printRow(row);
}
public static void printRows(ResultScanner resultScanner) {
for (Iterator<Result> iterator = results.iterator(); iterator.hasNext();) {
printRow(iterator.next();
}
}
public static void printRow(Result result) {
String returnString = "";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("id"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("type"))) + ", ";
returnString += Bytes.toString(result.getValue(Bytes.toBytes("cf"), Bytes.toBytes("date")));
System.out.println(returnString);
}
//}
Note that I use the setFilter
method, whereas the answer below uses the addFilter
method, on account of us using different APIs. 请注意,我使用setFilter
方法,而下面的答案使用addFilter
方法,因为我们使用不同的API。
You are using the HTable get
operation so you're only getting back one row (note that you can specify a prefix here as well and you don't have to give the complete key) 您正在使用HTable get
操作,因此您只返回一行(请注意,您也可以在此处指定前缀,而不必提供完整的密钥)
If you want to get back multiple rows you should use a Scan
如果要返回多行,则应使用“ Scan
byte[] prefix=Bytes.toBytes("1|A|");
Scan scan = new Scan(prefix);
PrefixFilter prefixFilter = new PrefixFilter(prefix);
scan.addFilter(prefixFilter);
ResultScanner resultScanner = table.getScanner(scan);
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