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Question

presto 新手，任何指针我如何在 presto 中使用 LATERAL VIEW EXPLODE 来查看下表。

我需要在我的 presto 查询中过滤名称

CREATE EXTERNAL TABLE `id`(
 `id` string,
 `names` map<string,map<string,string>>,
 `tags` map<string,map<string,string>>)
ROW FORMAT SERDE
 'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe' 
STORED AS INPUTFORMAT
 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat' 
OUTPUTFORMAT
 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION
 's3://test'

;

样本names 值：

{3081={short=Abbazia 81427 - Milan}, 2057={short=Abbazia 81427 - Milan}, 1033={short=Abbazia 81427 - Milan}, 4105={short=Abbazia 81427 - Milan}, 5129={short=Abbazia 81427 - Milan}}

Answer 1

来自文档：https://trino.io/docs/current/appendix/from-hive.html

Trino [原 PrestoSQL] 支持 UNNEST 扩展数组和映射。使用UNNEST 而不是LATERAL VIEW explode()。

Hive 查询：

SELECT student, score
FROM tests
LATERAL VIEW explode(scores) t AS score;

Presto 查询：

SELECT student, score
FROM tests
CROSS JOIN UNNEST(scores) AS t (score);

Answer 2

我可以在查询下方运行以获取映射数据

select
id
,names['1033']['short'] as srt_nm
from id;