An existing script creates text files with an array of JSON objects per line, e.g.,
[{"foo":1,"bar":2},{"foo":3,"bar":4}]
[{"foo":5,"bar":6},{"foo":7,"bar":8},{"foo":9,"bar":0}]
…
I would like to load this data in Pig, exploding the arrays and processing each individual object.
I have looked at using the JsonLoader in Twitter’s Elephant Bird to no avail. It doesn’t complain about the JSON, but I get “Successfully read 0 records” when running the following:
register '/tmp/elephant-bird/core/target/elephant-bird-core-4.3-SNAPSHOT.jar';
register '/tmp/elephant-bird/hadoop-compat/target/elephant-bird-hadoop-compat-4.3-SNAPSHOT.jar';
register '/tmp/elephant-bird/pig/target/elephant-bird-pig-4.3-SNAPSHOT.jar';
register '/usr/local/lib/json-simple-1.1.1.jar';
a = load '/path/to/file.json' using com.twitter.elephantbird.pig.load.JsonLoader('-nestedLoad=true');
dump a;
I have also tried loading the file as normal, treating each line as a containing a single column chararray, and then trying to parse that as JSON, but I can’t find a pre-existing UDF which seems to do the trick.
Any ideas?
Like Donald said, you should use a UDF here. Here in Xplenty we wrote JsonStringToBag to complement ElephantBird's JsonStringToMap.