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From "Slater, David M." <>
Subject BatchWriter performance on 1.4
Date Wed, 18 Sep 2013 21:07:49 GMT
Hi, I'm running a single-threaded ingestion program that takes data from an input source, parses
it into mutations, and then writes those mutations (sequentially) to four different BatchWriters
(all on different tables). Most of the time (95%) taken is on adding mutations, e.g. batchWriter.addMutations(mutations);
I am wondering how to reduce the time taken by these methods.

1) For the method batchWriter.addMutations(Iterable<Mutation>), does it matter for performance
whether the mutations returned by the iterator are sorted in lexicographic order?

2) If the Iterable<Mutation> that I pass to the BatchWriter is very large, will I need
to wait for a number of Batches to be written and flushed before it will finish iterating,
or does it transfer the elements of the Iterable to a different intermediate list?

3) If that is the case, would it then make sense to spawn off short threads for each time
I make use of addMutations?

At a high level, my code looks like this:

BatchWriter bw1 = connector.createBatchWriter(...)
BatchWriter bw2 = ...
while(true) {
String[] data = input.getData();
List<Mutation> mutations1 = parseData1(data);
                List<Mutation> mutations2 = parseData2(data);

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