feat: Distinct operator for queries

[kevin-dp]

This PR adds support for a SQL-like distinct operator on queries.
It works on top of electric-sql/d2ts#80 so we need to wait until that PR is merged and a new version of d2mini is released. Until then CI will be red.

[changeset-bot]

🦋 Changeset detected

Latest commit: d24f71e

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 6 packages

Name	Type
@tanstack/db	Patch
@tanstack/electric-db-collection	Patch
@tanstack/query-db-collection	Patch
@tanstack/react-db	Patch
@tanstack/vue-db	Patch
@tanstack/db-example-react-todo	Patch

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@tanstack/db

npm i https://pkg.pr.new/@tanstack/db@244

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@tanstack/query-db-collection

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commit: d24f71e

[samwillis]

This is great!

We should add a test to validate the behaviour when there is no select. We either support that, or don't. If it doesn't worth with no select it should throw an error when you try to use without a select. (I think it should work)

[samwillis]

@kevin-dp note that I bumped d2mini on your branch after releasing it. CI is green 😁

[kevin-dp]

This is great!

We should add a test to validate the behaviour when there is no select. We either support that, or don't. If it doesn't worth with no select it should throw an error when you try to use without a select. (I think it should work)

Yes distinct without select works. There's a test for that here: https://github.com/TanStack/db/pull/244/files#diff-92b5216ddf806ff91a92eeda5701f1093a170697b0328f3297f31ae30d2cde7bR180-R189
But it's not very useful because every row has a unique ID so there's nothing to de-duplicate.

[KyleAMathews]

If not useful should we just disallow it?

[samwillis]

Yep, let's require a select with a distinct. It make it much more explicit what it is doing - fewer foot guns.

[kevin-dp]

@KyleAMathews @samwillis i added an explicit check to disallow DISTINCT without a SELECT and modified the corresponding unit test accordingly.

[samwillis]

🚢

[KyleAMathews]