Loading and Retrieving Data from Pig

About this task

To use the HCatalog library HCatLoader and HCatStorer to load and retrieve data from Pig:

Procedure

  1. Create a table with the hcat utility. 
    hcat -e "create table hcatpig(key int, value string)"
  2. Verify that the table and table definition both exist. 
    hcat -e "describe formatted hcatpig"
  3. Load data into the table from Pig: Copy the $HIVE_HOME/examples/files/kv1.txt file into the MapRFS file system, then start Pig and load the file with the following commands: 
    pig -useHCatalog -Dfs.default.name=maprfs://CLDB_Host:7222/
grunt> A = LOAD 'kv1.txt' using PigStorage('\u0001') AS(key:INT, value:chararray);
grunt> STORE A INTO 'hcatpig' USING org.apache.hive.hcatalog.pig.HCatStorer();
  4. Retrieve data from the hcatpig table with the following Pig commands: Another way to verify that the data is loaded into the hcatpig table is by looking at the contents of maprfs://user/hive/warehouse/hcatpig/. HCatalog tables are also accessible from the Hive CLI. All Hive queries work on HCatalog tables. 
    B = LOAD 'default.hcatpig' USING org.apache.hive.hcatalog.pig.HCatLoader();
dump B; // this should display the records in kv1.txt