[IMPALA-2190] Complete conversion functions between timestamp, unixtime/epoch, and string dates

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.2
• Fix Version/s: Impala 2.3.0
• Labels: ramp-up
• Target Version: Product Backlog
• Assignee: Andre Calfa
• Reporter: Justin Erickson
• Created: 07/Aug/15 02:42
• Updated: 28/Mar/19 18:51
• Resolved: 24/Sep/15 23:11

Description

Related to IMPALA-2173, we should complete the conversion functions to go between timestamp, strings, and epoch

For converting to timestamp let's add:

• to_timestamp (bigint unixtime) - supported by Vertica, PostgreSQL
• to_timestamp (string date, [string pattern]) - supported by Oracle, PostgreSQL, IBM, Vertica

We can model this after PostgreSQL which provides a superset of the functionality: http://www.postgresql.org/docs/8.1/static/functions-formatting.html

While other engines don't have this we should add the following for completeness:

• from_timestamp (timestamp date, [string pattern]) like from_unixtime except takes argument of timestamp instead of string for date

We already have conversion from unixtime to string and conversion to unixtime:

• from_unixtime (bigint unixtime[, string format])
• unix_timestamp (timestamp date) returns unixtime as bigint
• unix_timestamp (string date, [string pattern]) returns unixtime as bigint

Issue Links

• is related to: IMPALA-8367 from_unixtime Bad date/time conversion format: u on NULL value
• is related to: IMPALA-5312 Timestamp functions from IMPALA-2190 are not documented