"Before I discovered [S3cmd](http://s3tools.org/s3cmd), I had been using the [S3 console](http://aws.amazon.com/console/) to do basic operations and [boto](https://boto.readthedocs.org/en/latest/) to do more of the heavy lifting. However, sometimes I just want to hack away at a command line to do my work.\n",
"\n",
"I've found S3cmd to be a great command line tool for interacting with S3 on AWS. S3cmd is written in Python, is open source, and is free even for commercial use. It offers more advanced features than those found in the [AWS CLI](http://aws.amazon.com/cli/)."
"Running the following command will prompt you to enter your AWS access and AWS secret keys. To follow security best practices, make sure you are using an IAM account as opposed to using the root account.\n",
"\n",
"I also suggest enabling GPG encryption which will encrypt your data at rest, and enabling HTTPS to encrypt your data in transit. Note this might impact performance."
"[S3DistCp](http://docs.aws.amazon.com/ElasticMapReduce/latest/DeveloperGuide/UsingEMR_s3distcp.html) is an extension of DistCp that is optimized to work with Amazon S3. S3DistCp is useful for combining smaller files and aggregate them together, taking in a pattern and target file to combine smaller input files to larger ones. S3DistCp can also be used to transfer large volumes of data from S3 to your Hadoop cluster."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"To run S3DistCp with the EMR command line, ensure you are using the proper version of Ruby:"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"rvm --default ruby-1.8.7-p374"
],
"language": "python",
"metadata": {},
"outputs": []
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"The EMR command line below executes the following:\n",
"* Create a master node and slave nodes of type m1.small\n",
"* Runs S3DistCp on the source bucket location and concatenates files that match the date regular expression, resulting in files that are roughly 1024 MB or 1 GB\n",
"For further optimization, compression can be helpful to save on AWS storage and bandwidth costs, to speed up the S3 to/from EMR transfer, and to reduce disk I/O. Note that compressed files are not easy to split for Hadoop. For example, Hadoop uses a single mapper per GZIP file, as it does not know about file boundaries.\n",
"\n",
"What type of compression should you use?\n",
"\n",
"* Time sensitive job: Snappy or LZO\n",
"* Large amounts of data: GZIP\n",
"* General purpose: GZIP, as it\u2019s supported by most platforms\n",
"\n",
"You can specify the compression codec (gzip, lzo, snappy, or none) to use for copied files with S3DistCp with \u2013outputCodec. If no value is specified, files are copied with no compression change. The code below sets the compression to lzo:"
"The CANCEL command will not abort a transaction. To abort or roll back a transaction, you must use the ABORT or ROLLBACK command. To cancel a query associated with a transaction, first cancel the query then abort the transaction.\n",
"\n",
"If the query that you canceled is associated with a transaction, use the ABORT or ROLLBACK. command to cancel the transaction and discard any changes made to the data:"