What is flatten in pig with example?
What is flatten in pig with example?
The FLATTEN operator which is an arithmetic 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. For example, consider a relation that has a tuple of the form (a, (b, c)).
What is 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.
Can we use Flatten to convert a bag into tuples?
Flatten un-nests bags and tuples. For tuples, the Flatten operator will substitute the fields of a tuple in place of a tuple whereas un-nesting bags is a little complex because it requires creating new tuples.
What is the default mode of pig?
Mapreduce Mode – To run Pig in mapreduce mode, you need access to a Hadoop cluster and HDFS installation. Mapreduce mode is the default mode; you can, but don’t need to, specify it using the -x flag (pig OR pig -x mapreduce).
What is the difference between Hive and Pig?
Apache Hive is a data warehouse and which provides an SQL-like interface between the user and the Hadoop distributed file system (HDFS) which integrates Hadoop….Difference between Pig and Hive :
| S.No. | Pig | Hive |
|---|---|---|
| 2. | Pig uses pig-latin language. | Hive uses HiveQL language. |
| 3. | Pig is a Procedural Data Flow Language. | Hive is a Declarative SQLish Language. |
What is explain in pig?
Advertisements. The explain operator is used to display the logical, physical, and MapReduce execution plans of a relation.
What is the default mode of Pig?
How do you start Pig in local mode?
Local Mode – To run Pig in local mode, you need access to a single machine; all files are installed and run using your local host and file system. Specify local mode using the -x flag (pig -x local). Tez Local Mode – To run Pig in tez local mode.
How do you write a Pig query?
Executing Pig Script in Batch mode
- Write all the required Pig Latin statements in a single file. We can write all the Pig Latin statements and commands in a single file and save it as . pig file.
- Execute the Apache Pig script. You can execute the Pig script from the shell (Linux) as shown below. Local mode.
Can a bag have duplicate tuples in Pig Latin?
Note the following about bags: A bag can have duplicate tuples. A bag can have tuples with differing numbers of fields. However, if Pig tries to access a field that does not exist, a null value is substituted. A bag can have tuples with fields that have different data types.
What’s the difference between a field and a pig relation?
A relation is a bag (more specifically, an outer bag). A bag is a collection of tuples. A tuple is an ordered set of fields. A field is a piece of data. A Pig relation is a bag of tuples. A Pig relation is similar to a table in a relational database, where the tuples in the bag correspond to the rows in a table.
When to use limit or order in pig?
A particular set of tuples can be requested using the ORDER operator followed by LIMIT.The LIMIT operator allows Pig to avoid processing all tuples in a relation. In most cases a query that uses LIMIT will run more efficiently than an identical query that does not use LIMIT.
Which is the correct syntax statement in Pig Latin?
Pig Latin syntax statement: cat path [path …] In general, uppercase type indicates elements the system supplies. In general, lowercase type indicates elements that you supply. (These conventions are not strictly adherered to in all examples.) a = LOAD ‘data’ AS (f1:int); Pig reserved keywords are listed here.