For #2, region.getClosestRowBefore() calls store.getRowKeyAtOrBefore(row)
Take a look at HStore#getRowKeyAtOrBefore() (around line 1619):
Iterator<StoreFile> sfIterator = this.storeEngine
.getStoreFileManager()
.getCandidateFilesForRowKeyBefore(state.getTargetKey());
while (sfIterator.hasNext()) {
StoreFile sf = sfIterator.next();
sfIterator.remove(); // Remove sf from iterator.
boolean haveNewCandidate = rowAtOrBeforeFromStoreFile(sf, state);
In short, I/O is likely in this code path.
On Fri, Oct 31, 2014 at 2:19 PM, Bora, Venu <[email protected]> wrote:
> Hello,
> 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?
>
>
> @Override
> 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, family);
> // 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);
> }
>
>
> Thanks
> Venu Bora
>
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