Add parse_ulid_timestamp() function

[rcoup]

Extracts the timestamp from a generated ULID

eg:

postgres=# select now(), parse_ulid_timestamp(generate_ulid());
              now              |     parse_ulid_timestamp
-------------------------------+----------------------------
 2020-01-08 14:04:43.441019+00 | 2020-01-08 14:04:43.441+00
(1 row)

[leocassarani]

Hi @rcoup, thanks for your contribution.

This is not a use case that we've ever come across and we were curious to hear what you were hoping to achieve with this function. The way we use ULIDs is as opaque identifiers and we've never expected to be able to retrieve the timestamp portion from an existing ULID.

Look forward to hearing from you.

[rcoup]

Used it for tracing & debugging: grabbing chunks of records associated with a time range or figuring out when a record appeared, in situations where for whatever reason there aren't associated timestamp fields.

Most of the language ULID implementations (Python, Go, etc) seem to have parse methods.

[pksunkara]

@rcoup FWIW, pgx_ulid supports casting to timestamp. I needed this feature for generating creation timestamps from id.