The other day I ran a Pig script. Nothing fancy; I loaded some data into HBase and then ran a second Pig job to do some aggregations. I knew the data loading would take some time as it was multiple GB of data, but I expected the second aggregation job to run much faster. It ran for over 15 hours and was not done at that time. This was too long in my mind and I terminated it. I was using Amazon Elastic Map Reduce as my Hadoop environment, so I could have add more resources, but I wasn’t sure if that would do me any good. I took a look at the performance break downs, and within minutes I found the problem. Not only, that I realized that even an expert would have had a hard time identifying the problem. What’s more, the goto fix for more performance in Hadoop, which is adding more hardware, would not have helped at all!
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