我有一个HBase表(来自java),我想按键列表查询该表。我做了以下操作,但它不起作用。
mFilterFeatureIt = mFeatureSet.iterator();
FilterList filterList=new FilterList(FilterList.Operator.MUST_PASS_ONE);
while (mFilterFeatureIt.hasNext()) {
long myfeatureId = mFilterFeatureIt.next();
System.out.println("FeatureId:"+myfeatureId+" , ");
RowFilter filter = new RowFilter(CompareOp.EQUAL,new BinaryComparator(Bytes.toBytes(myfeatureId)) );
filterList.addFilter(filter);
}
outputMap = HbaseUtils.getHbaseData("mytable", filterList);
System.out.println("Size of outputMap map:"+ outputMap.szie());
public static Map<String, Map<String, String>> getHbaseData(String table, FilterList filter) {
Map<String, Map<String, String>> data = new HashMap<String, Map<String, String>>();
HTable htable = null;
try {
htable = new HTable(HTableConfiguration.getHTableConfiguration(),table);
Scan scan = new Scan();
scan.setFilter(filter);
ResultScanner resultScanner = htable.getScanner(scan);
Iterator<Result> results = resultScanner.iterator();
while (results.hasNext()) {
Result result = results.next();
String rowId = Bytes.toString(result.getRow());
List<KeyValue> columns = result.list();
if (null != columns) {
HashMap<String, String> colData = new HashMap<String, String>();
for (KeyValue column : columns) {
colData.put(Bytes.toString(column.getFamily()) + ":"+ Bytes.toString(column.getQualifier()),Bytes.toString(column.getValue()));
}
data.put(rowId, colData);
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (htable != null)
try {
htable.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return data;
}
功能编号:80515900 ,功能编号:80515901 ,功能编号:80515902 ,
输出地图大小:0
我看到功能 id 的值是我想要的,但即使键存在于 hbase 表中,我也总是得到上面的输出。谁能告诉我我做错了什么?
编辑:我在上面也发布了我的 hbase util 方法的代码,以便您可以指出我那里的任何错误。
我正在尝试做一个 SQL 等效的 select * FROM mytable where featureId in (80515900, 80515901, 80515902)
我在 HBase 中实现相同目标的想法是创建一个过滤器列表,每个 featureId 都有一个过滤器。这是对的吗?
这是我的表格内容
scan 'mytable', {COLUMNS => ['sample:tag_count'] }
80515900 column=sample:tag_count, timestamp=1339304052748, value=4
80515901 column=sample:tag_count, timestamp=1339304052748, value=0
80515902 column=sample:tag_count, timestamp=1339304052748, value=3
80515903 column=sample:tag_count, timestamp=1339304052748, value=1
80515904 column=sample:tag_count, timestamp=1339304052748, value=2
它不会像将数据插入 hbase 时返回任何数据,
键的数据类型是"字符串"(来自扫描结果),在获取时,RowFilter 中传递的值具有"long"数据类型。使用此筛选器:
RowFilter filter = new RowFilter(CompareOp.EQUAL,new
BinaryComparator(Bytes.toBytes(myfeatureId.toString())) );
while 循环将始终生成一个新的过滤器并添加到过滤器列表中。
电路是滤波器中的所有键。此筛选器永远不能应用于单行。在 while 循环中只创建一个指向已知"myfeatureId"的过滤器。
while (mFilterFeatureIt.hasNext()) {
long myfeatureId = mFilterFeatureIt.next();
System.out.println("FeatureId:"+myfeatureId+" , ");
if ( myfeatureId=="80515902") {
RowFilter filter = new RowFilter(CompareOp.EQUAL,new BinaryComparator(Bytes.toBytes(myfeatureId)) );
filterList.addFilter(filter);
}
}
编辑
对于行数量,查询负责。HBase 不是
HBase 过滤器
筛选器将行选择条件推送到 HBase。可以远程和并行筛选行。使用这些函数有助于避免向客户端发送不需要的行。
要从钥匙中取出一部分,请从80515900获取所有内容..80515909试试这个
当然从循环中删除
RowFilter filter = new RowFilter(CompareOp.EQUAL,new BinaryComparator(Bytes.toBytes(myfeatureId)) );
filterList.addFilter(filter);
并在行上方添加outputMap = HbaseUtils.getHbaseData("mytable", filterList);
....
RowFilter filter = new RowFilter(CompareOp.EQUAL,new SubStringComparator("8051590"));
filterList.addFilter(filter);
outputMap = HbaseUtils.getHbaseData("mytable", filterList);