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From Bing Li <lbl...@gmail.com>
Subject Table and Family
Date Mon, 12 Aug 2013 16:22:46 GMT
Hi, all,

My understandings about HBase table and its family are as follows.

1) Each table can consist of multiple families;

2) When retrieving with SingleColumnValueFilter, if the family is
specified, other families contained in the same table are not
affected.

Are these claims right? But I got a problem which conflicts with the
above understandings.

In the following code, even though no any data in the family of
ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_BASICS_FAMILY, the
for-loop runs many times if other families has the column of
ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_DC_KEY_COLUMN.

Is that normal in HBase? If so, I think it is not a good design. No
column overlaps must exist among the families of the same table?
Otherwise, retrieving the table must cause waste of scanning loops?

Thanks so much!

Best wishes,
Bing

        SingleColumnValueFilter dcKeyFilter = new
SingleColumnValueFilter(ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_BASICS_FAMILY,
ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_DC_KEY_COLUMN,
CompareFilter.CompareOp.EQUAL, new SubstringComparator(dcKey));
        Scan scan = new Scan();
        scan.setFilter(dcKeyFilter);
        scan.setCaching(Parameters.CACHING_SIZE);
        scan.setBatch(Parameters.BATCHING_SIZE);

        String qualifier;
        String hostNodeKey = SocialRole.NO_NODE_KEY;
        String groupKey = SocialGroup.NO_GROUP_KEY;
        int timingScale = TimingScale.NO_TIMING_SCALE;
        String key;
        try
        {
            ResultScanner scanner = this.neighborTable.getScanner(scan);
            for (Result result : scanner)
            {
                for (KeyValue kv : result.raw())
                {
                    qualifier = Bytes.toString(kv.getQualifier());
                    if
(qualifier.equals(ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_HOST_NODE_KEY_STRING_COLUMN))
                    {
                        hostNodeKey = Bytes.toString(kv.getValue());
                    }
                    else if
(qualifier.equals(ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_HOST_GROUP_KEY_STRING_COLUMN))
                    {
                        groupKey = Bytes.toString(kv.getValue());
                    }
                    else if
(qualifier.equals(ContrivedNeighborStructure.NODE_NEIGHBOR_IN_GROUP_TIMING_SCALE_STRING_COLUMN))
                    {
                        timingScale = Bytes.toInt(kv.getValue());
                    }
                }
                if (!hostNodeKey.equals(SocialRole.NO_NODE_KEY) &&
!groupKey.equals(SocialGroup.NO_GROUP_KEY) && timingScale !=
TimingScale.NO_TIMING_SCALE)
                {
                    key = Tools.GetKeyOfNode(hostNodeKey, groupKey,
timingScale);
                    if (!neighborMap.containsKey(key))
                    {
                        neighborMap.put(key, new
NodeNeighborInGroup(hostNodeKey, groupKey, timingScale));
                    }
                }
                hostNodeKey = SocialRole.NO_NODE_KEY;
                groupKey = SocialGroup.NO_GROUP_KEY;
                timingScale = TimingScale.NO_TIMING_SCALE;
            }
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

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