Chapter 10. Hive Tuning
In this chapter, you will learn the following:
- Enabling predicate pushdown optimizations in Hive
- Optimizations to reduce the number of map
Enabling predicate pushdown optimizations in Hive
In this recipe, you will learn how to use predicate pushdown in Hive.
Predicate pushdown is a traditional RDBMS term, whereas in Hive, it works as predicate pushup. In this, the focus is on to execute all the expressions such as filters as early as possible to optimize the performance of a query. For example, let's look at the query mentioned later, which includes a join condition as well as a filter condition:
SELECT a.*, b.* FROM Sales a JOIN Sales_orc b ON a.id = b.id WHERE a.id > 100 AND b.id > 300;
In the preceding ...