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Deconstruct Impala queries

Deconstruct Impala queries - Hadoop Tutorial

From the course: Hadoop for Data Science Tips, Tricks, & Techniques

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Deconstruct Impala queries

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- [Instructor] Now I want to figure out how to see what the Impala engine is doing when I write a query. I like to think of this as deconstructing these Impala queries. We'll start out with some basics, then we'll get into some more difficult types of queries, and I'll explain what's happening throughout that and show you how you can inspect it, which is really helpful if you're running into any performance issues. First, let's just do a basic query from the table we built. Select * from customer_orders, limit 100. You can see I have my results there. If I add explain to the beginning of this, I'll get a query plan. If I scroll down, you can see how this works. If you haven't ran any queries yet, you'll need to do compute stats, so let's just do that first. I'll do this on a new line and put compute stats on our table here, default.customer_orders. Run this, and hit play. That way it'll calculate everything that's going on with that table. Then when we run our query again, we'll get…

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