Learn how to create a flat table and then join to it in Impala.
- [Instructor] One of the reasons we like…to flatten out tables in Hive is…because we want to use Impala.…Impala is a faster query engine that Cloudera offers,…which is really nice especially…when you're working with big data.…So we've just looked at how to do a bunch…with these complex structures,…including how to actually flatten most of them out…using the lateral view explode option.…So I want to show you now just the next step,…which would be to store that as a table…so you can join it to other Impala objects.…
So I'm going to paste in a query…that we just used in the previous clip.…So if you didn't follow along with that one,…you can either get this from the exercise files…or you can just go back and follow along…and write it out with me.…So I'll expand this here and I'm in Hue,…and I'll just go through this real quick.…So we have a common table expression,…which is for the select query here,…which just is a lateral view explode on orders.…Then we go down and we use that…and we pull out the order id…and in this time we're actually creating a timestamp…
- Explain which commands are used to make changes in HDFS.
- Identify the commands used to upload data from the command line to the HDFS.
- Recognize two operations the HDFS performs when a user moves files.
- Summarize how to remove files recursively in HDFS.
- Recall how to select and implement partitions.
- Explain how to flatten a Struct data type in HiveQL.