07-08-2019 08:19 AM
Is Cloudera suggesting to use S3Guard as a solution for the consistency problem in multi-step ETL? Cause in the reference architecture, the suggested option is to load data from S3 into HDFS and then write back to S3?
07-09-2019 12:53 AM - edited 07-09-2019 12:55 AM
Yes that is correct, and the motivations/steps-to-use are reflected here too: https://www.cloudera.com/documentation/enterprise/6/latest/topics/cm_s3guard.html
Note: On your point of 'load data from S3 into HDFS', it is better stated as simply 'read data from S3', where HDFS gets used as a transient storage (where/when required). There does not need to be a 'download X GiB data from S3 to HDFS first, only then begin jobs' step, as distributed jobs can read off of S3 via s3a:// URLs in the same way they do from HDFS hdfs://.