Parse json arrays using HIVE

Question

I have many json arrays stored in a table (jt) that looks like this:

[{"ts":1403781896,"id":14,"log":"show"},{"ts":1403781896,"id":14,"log":"start"}]
[{"ts":1403781911,"id":14,"log":"press"},{"ts":1403781911,"id":14,"log":"press"}]

Each array is a record.

I would like to parse this table in order to get a new table (logs) with 3 fields: ts, id, log. I tried to use the get_json_object method, but it seems that method is not compatible with json arrays because I only get null values.

This is the code I have tested:

CREATE TABLE logs AS 
SELECT get_json_object(jt.value, '$.ts') AS ts, 
get_json_object(jt.value, '$.id') AS id,
get_json_object(jt.value, '$.log') AS log
FROM jt;

I tried to use other functions but they seem really complicated. Thank you! :)

Update! I solved my issue by performing a regexp:

CREATE TABLE jt_reg AS
select regexp_replace(regexp_replace(value,'\\}\\,\\{','\\}\\\n\\{'),'\\[|\\]','') as valuereg  from jt;


CREATE TABLE logs AS 
SELECT get_json_object(jt_reg.valuereg, '$.ts') AS ts, 
get_json_object(jt_reg.valuereg, '$.id') AS id,
get_json_object(jt_reg.valuereg, '$.log') AS log
FROM ams_json_reg;

Answer 1

Use explode() function

 hive (default)> CREATE TABLE logs AS
                  >   SELECT get_json_object(single_json_table.single_json, '$.ts') AS ts,
                  >   get_json_object(single_json_table.single_json, '$.id') AS id,
                  >   get_json_object(single_json_table.single_json, '$.log') AS log
                  >   FROM
                  >     (SELECT explode(json_array_col) as single_json FROM jt) single_json_table ;

Automatically selecting local only mode for query
Total MapReduce jobs = 3
Launching Job 1 out of 3
Number of reduce tasks is set to 0 since there's no reduce operator

hive (default)> select * from logs;
OK
ts      id      log
1403781896      14      show
1403781896      14      start
1403781911      14      press
1403781911      14      press
Time taken: 0.118 seconds, Fetched: 4 row(s)
hive (default)>

where json_array_col is column in jt which holds your array of jsons.

hive (default)> select json_array_col from jt;
json_array_col
["{"ts":1403781896,"id":14,"log":"show"}","{"ts":1403781896,"id":14,"log":"start"}"]
["{"ts":1403781911,"id":14,"log":"press"}","{"ts":1403781911,"id":14,"log":"press"}"]