How can we use the Pig command for big data?

2 years ago
Liam
2 minutes

Pig is a tool used for large-scale data analysis on Hadoop, processing data in a syntax similar to SQL. Here is how to use Pig commands:

  1. To start Pig: simply type “pigg” in the terminal window.
  2. Load data: use the LOAD command to load data from the Hadoop file system. For example, LOAD ‘inputfile’ USING PigStorage(‘,’) AS (col1:datatype, col2:datatype, …);
  3. Store data: Use the STORE command to write data into the Hadoop file system. For example, STORE tablename INTO ‘outputfile’ USING PigStorage(‘,’);
  4. Filtering data: Use the FILTER command to filter data based on specified conditions. For example, result = FILTER tablename BY condition;
  5. Sort data: Use the ORDER command to sort the data. For example, ordered_data = ORDER tablename BY col;
  6. Grouping data: Use the GROUP command to group the data. For example, grouped_data = GROUP tablename BY col;
  7. Generate aggregate statistics: Use the GROUP command along with aggregate functions to aggregate data. For example, aggregated_data = GROUP tablename ALL;
  8. Merge data: Use the JOIN command to combine multiple datasets together. For example, the joined_data = JOIN table1 BY col, table2 BY col;
  9. Calculate data: Use the FOREACH command to compute each piece of data. For example, calculated_data = FOREACH tablename GENERATE expression;
  10. Restrict data: Use the LIMIT command to restrict the number of data records output. For example, limited_data = LIMIT tablename 10;
  11. Define aliases: Use the AS command to give a middle result or computation result an alias. For example, result1 = LOAD ‘file1’ AS (col1:datatype, col2:datatype); command will load data into the alias result1.
  12. Commenting code: Use the – or /* */ commands to add comments to explain the code.

Please note that the above are just some common uses of Pig commands; there are actually more commands and options available for use. You can refer to the official Pig documentation for a more detailed list of commands and usage instructions.

bannerAds