At the end of this video the student will know how to join multiple tables together in Hive.
- [Narrator] So here, let's take a look…at joining multiple tables together.…Now, Hive joins are cumulative,…meaning that they are executed in sequential order.…And as you join, the results from one previous join…are going to be filtering out data as you go down.…So you need to be really cognizant…of how you order your joins…so that way you don't get invalid results.…Let's take a look at a simple query here.…We have SELECT a.val, b.val, c.val…FROM a JOIN b…and then LEFT OUTER JOIN c.…
So what's going to happen is…it's going to join a to b…and discard anything that's unmatched…because we're doing an inner join.…Then the results of the join from a to b…are going to be joined to c.…And we're only going to return those results from c…that match and keep everything from that first join…because we're doing a left outer join.…So remember, these are cumulative.…So as we go down here, our result set's going…to get smaller and smaller.…Let's take a look at this in real life.…First, we're going to join to the vip_clients table.…
This course shows how to use Hive to process data. Instructor Ben Sullins starts by showing you how to structure and optimize your data. Next, he explains how to get Hue, the Hadoop user interface, to leverage HiveQL when analyzing data. Using the newly configured option, he then demonstrates how to load data, create aggregate tables for fast query access, and run advanced analytics. He also takes you through managing tables and putting functions to use. This course is designed to help you find new ways to work with datasets so you can answer the tough data science questions that come your way.
- Defining data structures in Hive
- Selecting data
- Joining tables
- Manipulating data
- Filtering results
- Aggregating data
- Using built-in aggregate functions
- Mastering built-in table-generating functions
- Using CUBE and ROLLUP
- Using clauses: WHERE and HAVING
- Using LIKE, JOIN, and SEMI JOIN
- Using functions: String, math, date, and conditional