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有很多關於如何使用JsonLoader()
從文件中加載JSON數據與模式的例子,但不是來自任何其他輸出。如何解碼來自列的Pig中的JSON?
有很多關於如何使用JsonLoader()
從文件中加載JSON數據與模式的例子,但不是來自任何其他輸出。如何解碼來自列的Pig中的JSON?
您正在尋找象鳥提供的JsonStringToMap UDF:https://github.com/kevinweil/elephant-bird/search?q=JsonStringToMap&ref=cmdform
示例文件:
foo bar {"version":1, "type":"an event", "count": 1}
foo bar {"version":1, "type":"another event", "count": 1}
豬腳本:
REGISTER /path/to/elephant-bird.jar;
DEFINE JsonStringToMap com.twitter.elephantbird.pig.piggybank.JsonStringToMap();
raw = LOAD '/tmp/file.tsv' USING PigStorage('\t') AS (col1:chararray,col2:chararray,json_string:chararray);
parsed = FOREACH raw GENERATE col1,col2,JsonStringToMap(json_string);
ILLUSTRATE parsed; -- Just to show the output
預處理(JSON作爲chararray /串):
-------------------------------------------------------------------------------------------------------
| raw | col1:chararray | col2:chararray | json_string:chararray |
-------------------------------------------------------------------------------------------------------
| | foo | bar | {"version":1, "type":"another event", "count": 1} |
後處理(JSON如地圖):
-------------------------------------------------------------------------------------------------
| parsed | col1:chararray | col2:chararray | json:map(:chararray) |
-------------------------------------------------------------------------------------------------
| | foo | bar | {count=1, type=another event, version=1} |
-------------------------------------------------------------------------------------------------
重複