如何在Hive中将JSON字符串数据类型列转换为映射数据类型列？

Question

我需要从所有行中获取所有唯一键值。 每行具有不同的键和值。请找到该列的上图。

例如：一行看起来像

{"START_TIME":1549002807568,"PARSING.QUERY_FORMED":1549002807586,"CUBES_WITH_PERMISSIONS":1549002807568,"PARSING.CUBE_MATCH_SELECTED":1549002807586,"POTENTIAL_COMPLETIONS_ADDED":1549002807587,"QUERY_PARSED":1549002807586,"SUGGESTIONS_FORMED":1549002807606,"PARSING.SEQUENCES_GENERATED":1549002807568,"PARSING.NGRAM_MATCHES_CACHED":1549002807585}

Answer 1

使用两行数据对此进行了测试，所有键值对均相同，只是在第二个JSON中，还有一个另外的NEW_KEY和PARSING.NGRAM_MATCHES_CACHED值不同。

with data as
(
select stack(2, --data example
'{"START_TIME":1549002807568,"PARSING.QUERY_FORMED":1549002807586,"CUBES_WITH_PERMISSIONS":1549002807568,"PARSING.CUBE_MATCH_SELECTED":1549002807586,"POTENTIAL_COMPLETIONS_ADDED":1549002807587,"QUERY_PARSED":1549002807586,"SUGGESTIONS_FORMED":1549002807606,"PARSING.SEQUENCES_GENERATED":1549002807568,"PARSING.NGRAM_MATCHES_CACHED":1549002807585}',
'{"NEW_KEY":12345,"START_TIME":1549002807568,"PARSING.QUERY_FORMED":1549002807586,"CUBES_WITH_PERMISSIONS":1549002807568,"PARSING.CUBE_MATCH_SELECTED":1549002807586,"POTENTIAL_COMPLETIONS_ADDED":1549002807587,"QUERY_PARSED":1549002807586,"SUGGESTIONS_FORMED":1549002807606,"PARSING.SEQUENCES_GENERATED":1549002807568,"PARSING.NGRAM_MATCHES_CACHED":154900280758}'
) as str
)

select str_to_map(concat_ws(',',collect_set(key_value)),',',':') --collect set, concatenate and convert to map
from
(
select explode(split(regexp_replace (str,'[{}"]',''),',')) key_value from data --remove JSON delimiters, split and explode pairs
)s;

结果：

OK
{"START_TIME":"1549002807568","PARSING.QUERY_FORMED":"1549002807586","CUBES_WITH_PERMISSIONS":"1549002807568","PARSING.CUBE_MATCH_SELECTED":"1549002807586","POTENTIAL_COMPLETIONS_ADDED":"1549002807587","QUERY_PARSED":"1549002807586","SUGGESTIONS_FORMED":"1549002807606","PARSING.SEQUENCES_GENERATED":"1549002807568","PARSING.NGRAM_MATCHES_CACHED":"154900280758","NEW_KEY":"12345"}
Time taken: 158.414 seconds, Fetched: 1 row(s)

当然，"PARSING.NGRAM_MATCHES_CACHED"在结果中仅存在一次，因为map不允许同一密钥两次。所有键值都是唯一的。 请阅读代码中的注释。