https://stackoverflow.com/questions/49514280/how-to-convert-string-into-timestamp-in-presto-athena

• Firehose → Glue 에선 String으로 저장
• Athena에서 테이블 생성할 때도 String으로 저장
• 쿼리할 때 date_parse(timestamp,'%Y/%m/%d %H:%i:%s') 사용
• 날짜 보기
  • http://teradata.github.io/presto/docs/127t/functions/datetime.html

# float -> timestamp
select from_unixtime(CAST(time AS bigint)) from mytable;

# string -> timestamp
select date_parse(timestamp,'%Y/%m/%d %H:%i:%s') from mytable;