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From "Bora, Venu" <venu.b...@epsilon.com>
Subject How to findout Hbase PUT inserts a new Row or Update an exisiting row
Date Fri, 31 Oct 2014 21:19:06 GMT
We have a requirement to determine whether a PUT will create a new row or update an existing
one. I looked at using preBatchMutate in a co-processor and have the code below.

Few things I need to ask:
1) Is there a more efficient way of doing this?
2) Will region.getClosestRowBefore() add additional IO to go to disk? or will the row be in
memory since the row lock was already acquired before preBatchMutate is called?
3) Will region.getClosestRowBefore() always give the correct result? Or are there scenarios
where the previous state will not be visible?

    public void preBatchMutate(ObserverContext<RegionCoprocessorEnvironment> c, MiniBatchOperationInProgress<Mutation>
miniBatchOp) throws IOException {
        for (int i = 0; i < miniBatchOp.size(); i++) {
            Mutation operation = miniBatchOp.getOperation(i);
            byte[] rowKey = operation.getRow();
            NavigableMap<byte[], List<Cell>> familyCellMap = operation.getFamilyCellMap();

            for (Entry<byte[], List<Cell>> entry : familyCellMap.entrySet()) {
                for (Iterator<Cell> iterator = entry.getValue().iterator(); iterator.hasNext();)
                    Cell cell = iterator.next();
                    byte[] family = CellUtil.cloneFamily(cell);
                    Result closestRowBefore = c.getEnvironment().getRegion().getClosestRowBefore(rowKey,
                    // closestRowBefore would return null if there is not record for the rowKey
and family
                    if (closestRowBefore != null) {
                        // PUT is doing an update for the given rowKey, family
                    } else {
                        // PUT is doing an insert for the given rowKey, family
        super.preBatchMutate(c, miniBatchOp);

Venu Bora


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