Partial timestamp support

[dlurton]

According to this comment timestamps aren't supported yet. Let's change that.

Since my team isn't using PartiQL Rust's parser and are instead interfacing directly with the IR, and we have a very specific use-case for timestamps, full support for timestamps is not required.

Here's the minimal subset of timestamp support that my team needs that I am currently aware of:

• A representation in enum Value for timestamps with at least microsecond precision.
• Support for using timestamps in = and <= operators.

At this time, my team does not need:

• Support for timestamps in the parser.
• Functions to manipulate timestamps (e.g. to_timestamp, date_add, etc)
• The ability to represent timestamps with arbitrary precision.

Which will hopefully make this request relatively bite-sized.

[alancai98]

According to this comment timestamps aren't supported yet. Let's change that.

We currently have support for timestamps as of the v0.3.0 release:

partiql-lang-rust/partiql-value/src/lib.rs

Line 51 in 380f526

DateTime(Box<DateTime>),

Perhaps you were looking at an older version of partiql-lang-rust?

• A representation in enum Value for timestamps with at least microsecond precision.
• Support for using timestamps in = and <= operators.

The current time and timestamp values support precision of nanosecond and have an impl/derived implementation for = and <= operators.

Regarding your other points,

• We are working to add support for timestamps in the parser through Adds lowering of DATE, TIME, and TIMESTAMP literals to logical plan #345. You can already add parse Ion timestamps in the parser with the backticks
• We plan to add some more datetime-related functions. Are there any you think you'll need in particular?
• We haven't yet started representing timestamps with arbitrary precision

[dlurton]

Oh, well, I guess I stand corrected! Didn't realize my local copy was out so of date. 😳 Thanks.