Question

I have a HBase table (from java) and i want to query the table by list of keys. I did the following, but its not working.

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;
}

FeatureId:80515900 ,
FeatureId:80515901 ,
FeatureId:80515902 ,

Size of outputMap map: 0

I see that value of feature id is what i want , but I always get the above output even if the key is present in the hbase table. Can anyone tell me what am i doing wrong ?

EDIT:
I posted the code for my hbase util method too above, so that you can point me to any bugs there.

I am trying to do an SQL equivalent of select * FROM mytable where featureId in (80515900, 80515901, 80515902) My idea to achieve the same in HBase was to create a filter list with one filter for each featureId. Is that correct ?

Here is the content of my table

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                                                                                                

Answer 1

Its not returning any data as while inserting the data into hbase,
the data-type for key is ‘String’ (from your scan result) & while fetching, the value passed in RowFilter has ‘long’ data type. Use this filter:

RowFilter filter = new RowFilter(CompareOp.EQUAL,new    
BinaryComparator(Bytes.toBytes(myfeatureId.toString())) );