How do you count Pig Records?
To get the global count value (total number of tuples in a bag), we need to perform a Group All operation, and calculate the count value using the COUNT() function. To get the count value of a group (Number of tuples in a group), we need to group it using the Group By operator and proceed with the count function.
How do you use order by in pig?
Example of ORDER BY Operator
- grunt> Result = ORDER A BY a1 DESC;
- grunt> DUMP Result;
How do you find the average of a pig?
Apache Pig – AVG()
- To get the global average value, we need to perform a Group All operation, and calculate the average value using the AVG() function.
- To get the average value of a group, we need to group it using the Group By operator and proceed with the average function.
What is flatten in pig?
As per Pig documentation: The FLATTEN operator looks like a UDF syntactically, but it is actually an operator that changes the structure of tuples and bags in a way that a UDF cannot. Flatten un-nests tuples as well as bags. The idea is the same, but the operation and result is different for each type of structure.
How do you count in Pig Latin?
Word Count in Pig Latin
- Load the data from HDFS. Use Load statement to load the data into a relation . As keyword used to declare column names, as we dont have any columns, we declared only one column named line.
- Convert the Sentence into words. The data we have is in sentences.
- Convert Column into Rows.
What do you mean by a bag in Pig?
A bag is a collection of tuples. A tuple is an ordered set of fields. A field is a piece of data.
How do you join a key and value in Pig?
Here is how you can perform a JOIN operation on two tables using multiple keys. grunt> Relation3_name = JOIN Relation2_name BY (key1, key2), Relation3_name BY (key1, key2);
What is eval function in pig?
Eval functions: AVG(col): computes the average of the numerical values in a single column of a bag. CONCAT(string expression1, string expression2) : Concatenates two expressions of identical type. COUNT(DataBag bag): Computes the number of elements in a bag excluding null values.
Which of the following operator is used to compute the average of the numerical values within a bag?
AVG()
We use AVG(), to compute the average of the numerical values within a bag.
What is tuple in Pig?
What is foreach in Pig?
The FOREACH operator is used to generate specified data transformations based on the column data.
Is null in Pig?
In Pig Latin, nulls are implemented using the SQL definition of null as unknown or non-existent.
What is a bag in Pig?
Grouping Within a Bag Pig has a GROUP operation that can be applied to a relation. It produces a new relation where the input tuples are grouped by a particular key. A bag in the relation contains the grouped tuples for that key. The key is represented by a group parameter. BagGroup mimics the GROUP operation from Pig.
What is map in Pig?
A map in Pig is a chararray to data element mapping, where that element can be any Pig type, including a complex type. The chararray is called a key and is used as an index to find the element, referred to as the value. Because Pig does not know the type of the value, it will assume it is a bytearray.
Why pig is faster than Hive?
Especially, for all the data load related work While you don’t want to create the schema. Since it has many SQL-related functions and additionally you have cogroup function as well. It does support Avro Hadoop file format. Pig is faster than Hive.
What is the default join in pig?
Self-join is used to join a table with itself as if the table were two relations, temporarily renaming at least one relation. Generally, in Apache Pig, to perform self-join, we will load the same data multiple times, under different aliases (names).
What are the different complex data types in Pig?
Complex Types. Pig has three complex data types: maps, tuples, and bags. All of these types can contain data of any type, including other complex types. So it is possible to have a map where the value field is a bag, which contains a tuple where one of the fields is a map.