Fix a bug that could result in a duplicate delete event for a row

[samwillis]

fixes #609

We had code in place that filtered out redundant change events from sync operations, but it failed to filter delete events, only filtering insert/update.

CI run with test failure showing the repo before the fix is applied: https://github.com/TanStack/db/actions/runs/18163302240/job/51698976831?pr=621

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@tanstack/solid-db	Patch
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commit: b41e365

[github-actions]

Size Change: +36 B (+0.05%)

Total Size: 74.1 kB

Filename	Size	Change
./packages/db/dist/esm/collection/state.js	3.81 kB	+36 B (+0.95%)

ℹ️ View Unchanged

Filename	Size
./packages/db/dist/esm/collection/change-events.js	958 B
./packages/db/dist/esm/collection/changes.js	1.01 kB
./packages/db/dist/esm/collection/events.js	683 B
./packages/db/dist/esm/collection/index.js	3.14 kB
./packages/db/dist/esm/collection/indexes.js	1.16 kB
./packages/db/dist/esm/collection/lifecycle.js	1.8 kB
./packages/db/dist/esm/collection/mutations.js	2.59 kB
./packages/db/dist/esm/collection/subscription.js	1.69 kB
./packages/db/dist/esm/collection/sync.js	1.32 kB
./packages/db/dist/esm/deferred.js	230 B
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./packages/db/dist/esm/indexes/auto-index.js	745 B
./packages/db/dist/esm/indexes/base-index.js	605 B
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./packages/db/dist/esm/local-only.js	827 B
./packages/db/dist/esm/local-storage.js	2.02 kB
./packages/db/dist/esm/optimistic-action.js	294 B
./packages/db/dist/esm/proxy.js	3.87 kB
./packages/db/dist/esm/query/builder/functions.js	615 B
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./packages/db/dist/esm/query/compiler/index.js	2.04 kB
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./packages/db/dist/esm/query/live/collection-subscriber.js	1.91 kB
./packages/db/dist/esm/query/optimizer.js	3.1 kB
./packages/db/dist/esm/SortedMap.js	1.24 kB
./packages/db/dist/esm/transactions.js	3.03 kB
./packages/db/dist/esm/utils.js	943 B
./packages/db/dist/esm/utils/browser-polyfills.js	365 B
./packages/db/dist/esm/utils/btree.js	6.02 kB
./packages/db/dist/esm/utils/comparison.js	754 B
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Size Change: 0 B

Total Size: 1.44 kB

ℹ️ View Unchanged

Filename	Size
./packages/react-db/dist/esm/index.js	152 B
./packages/react-db/dist/esm/useLiveQuery.js	1.29 kB

_{compressed-size-action::react-db-package-size}

[KyleAMathews]

I don't love really that we do all these deepEquals — they're fairly expensive — but I suppose cheaper than the UI framework re-rendering the same bits of UI 🤷

[KyleAMathews]

In this particular case, we don't actually need a deepEqual right? Since a delete is a delete is a delete. If the optimistic mutation got rid of it already, we can just immediately assume the synced delete is the same?

[samwillis]

The deepEquals are not really about stoping re-renders, they are deduplicating events in the same batch that could result in an invalid state. This is particularly important when feeding into the d2 graph as aggregates could become wrong, or the multiplicity could and we then track inserts/deletes later incorrectly.

I agree, I would prefer not to have them, but I think we should approach that in a general redesign of this reconciliation process - I don't particularly like how it currently works.

In this particular case, we don't actually need a deepEqual right?
Maybe, but I don't really want to bet on it. It's still about removing duplicates and there could be multiple deletes for the same key in the same batch. We just want to ensure the state inside d2 is correct. I don't want to make an assumption, I would prefer to take a belt and braces at this point before we further refactor.

Do note that these deepEquals are only happening on optimistic mutations, not on every change that is synced, and not on every emitted initial state into the live query engine. As overhead it's tiny compared to the other things happening in D2.

[KyleAMathews]

Do note that these deepEquals are only happening on optimistic mutations, not on every change that is synced

Ah ok, so very little generally 👍

[KyleAMathews]