feat: Add the interval type to Spanner

[Hectorhammett]

Adds an Interval type for Spanner.

[amanda-tarafa]

I've just reviewed the Interval type itself on this round.
Let's get that right before going into the rest.

[amanda-tarafa]

We probably need more docs here. A link to Spanner's Interval type docs is probably fine.

[amanda-tarafa]

Gentle ping on this one.

[Hectorhammett]

Huh I thought the Spanner Interval type was not ready, but perhaps I am mistaken.

Is this a case of referencing something specifically?

[amanda-tarafa]

Nope, you are absolutely right. Maybe leave a TODO on your personal notes to come back here and add a link to the docs when they are public.

[amanda-tarafa]

This is lossy, is that acceptable?

[Hectorhammett]

To my testing this is the easier way to make this conversion. On my first implementations before actually making this draft, using FLOAT was giving me rounding errors, but after several iterations I landed on this solution.

If we multiply the decimal type by NanosecondsInASecond is basically turning it into an int and removing the decimal point. Another solution I can think of is doing a direct String manipulation to have this value turn into a BigInteger? Removing the decimal point and adding as many 0s as needed for the conversion?

[amanda-tarafa]

@Hectorhammett see how this looks like. No Regex and I think it's pretty clear.

It's a console app so it needs tweaking to be used here, and I stopped at the point of extracting each of the parts, that is I didn't combined the parts in the 3 fields months, days and nanos, but that should be easy enough.

Code here: https://gist.github.com/amanda-tarafa/af0f21b45c7a461fcefd11a3e6ca8136

[jskeet]

Yes, I like this approach.

My NodaTime code doing similar work is here, but Amanda's is cleaner, I think.
https://github.com/nodatime/nodatime/blob/main/src/NodaTime/Text/PeriodPattern.cs#L215

(It's possible that I don't detect a period ending in 'T' though - I need to check that at some point.)

[Hectorhammett]

I like this one over the regex as well. Let me take a jab at it and run the tests and will update the code accordingly :)

[amanda-tarafa]

Most important changes are for missing tests. The rest is more around style and idiomatic coding, etc.

Use the protobuf pr as a reference: #13189

But we need to add this type to:

• AllTypesTableFixture
• BindingTests
• GetSchemaTableTests
• WriteTests
• SpannerParameterTest

A lot of these are integration tests that we couldn't have run until now, anyway.

[amanda-tarafa]

Gentle ping on this one.