[IMPALA-5766] Add date/timestamp format options to external tables

• Type: New Feature
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Frontend
• Labels: timestamp
• Environment: impala 2.2
• Target Version: Product Backlog
• Epic Color: ghx-label-3
• Assignee: Unassigned
• Reporter: Venu Yanamandra
• Created: 04/Aug/17 19:17
• Updated: 03/Oct/17 23:49

Description

Could we support more than one date separator while automatically parsing string timestamp columns. If possible, could we also enhance to specify a common timestamp format for a table?
In detail:
------------
External table:
CREATE EXTERNAL TABLE videowatchactivity(
id int,
user string,
activitydttm timestamp,
videoid string,
activity string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LOCATION '/user/videologger/activity';

If HDFS file: "/user/videologger/activity/activity_aug_4_2017.csv" contains -->
Venu,2017-08-04 11:23:00,video_id_0,start
Venu,2017-08-04 11:25:00,video_id_0,stop
Then,
"select activitydttm from videowatchactivity;" outputs 2 valid rows.

If HDFS file: /user/videologger/activity/activity_aug_4_2017.csv contains -->
Venu,2017/08/04 11:23:00,video_id_0,start
Venu,2017/08/04 11:25:00,video_id_0,stop
Then,
"select activitydttm from videowatchactivity;" outputs 2 NULL rows.

Could there be a provision to specify the date separator in the create table statement that could be used in the logic to automatically parse strings to timestamp columns?
E.g.,
CREATE EXTERNAL TABLE videowatchactivity(
id int,
user string,
activitydttm timestamp,
videoid string,
activity string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY ','
LOCATION '/user/videologger/activity'
DATESEPARATOR '/';
Please note the new "DATESEPARATOR '/'" that could help us define any separator for the date field.

If possible to extend, we could also use a new DATEFMT property of the table to specify a format like==> MM-dd-YYYY HH:mm:ss instead of the default format too.

Thanks,

Issue Links

• is blocked by: IMPALA-4018 Add support for SQL:2016 datetime templates/patterns/masks to CAST(... AS ... FORMAT <template>)
• is related to: HIVE-9298 Support reading alternate timestamp formats