Free Practice Questions for EMC D-DS-FN-23 Exam

The EXCEPT operator returns rows that exist in the result set of the first SELECT statement but not in the second. It removes duplicates and only shows the difference between the two datasets.

The GROUP BY clause in the SQL statement implies the use of an aggregate function. In this case, avg(prod_cost) is an aggregate function that calculates the average of the product costs for each group of products.

In a user-defined aggregate function (UDAF), FFUNC refers to the optional final calculation function. It is used to perform any final calculation or transformation on the aggregated result before it is returned to the user.

The Partial Autocorrelation Function (PACF) is examined to identify the order of the autoregressive (AR) component in an ARIMA model. It helps determine how much of the autocorrelation is explained by previous lags, assisting in selecting the appropriate AR order.

The Hadoop Distributed File System (HDFS) is a master/slave system designed to run on commodity hardware, meaning it can efficiently store large volumes of data across inexpensive, off-the-shelf hardware.

Hadoop is primarily written in Java. It is built on the Java programming language to provide a framework for distributed storage and processing of large datasets.

The Scheduler in Hadoop is responsible for allocating compute and memory resources across various applications running on the cluster. It decides how resources are distributed based on policies and availability.