fix(db-ivm): use row keys for stable ORDER BY tie-breaking

[samwillis]

Summary

• Replace hash-based object ID tie-breaking with direct key comparison for deterministic ordering when ORDER BY values are equal
• Simplify internal data structures by removing the TaggedValue abstraction
• Remove globalObjectIdGenerator dependency from the topK operators

Problem

When multiple rows have equal ORDER BY values, the previous implementation used globalObjectIdGenerator.getId(key) to generate a numeric tag for tie-breaking. This had several issues:

1. Hash collisions: The simple hash function could produce the same value for different keys
2. Unstable for objects: Object references get auto-incrementing IDs, which aren't stable across page reloads
3. Unnecessary complexity: The TaggedValue<K, V> = [K, V, Tag] 3-tuple added overhead

Solution

Use the row key directly for tie-breaking:

// Before (hash-based, potentially unstable):
const tieBreakerA = getTag(a)  // globalObjectIdGenerator.getId(key)
const tieBreakerB = getTag(b)
return tieBreakerA - tieBreakerB

// After (stable, deterministic):
if (aKey === bKey) return 0
if (aKey < bKey) return -1
return 1

This works because:

• Row keys are always string | number (from collection's getKey)
• Each key appears at most once in the topK (enforced by multiplicity tracking)
• Direct comparison is deterministic and stable across sessions

Changes

• topKWithFractionalIndex.ts:
  • Replace TaggedValue<K, V> with [K, T] tuple
  • Use direct key comparison for tie-breaking
  • Remove globalObjectIdGenerator import
  • Remove tagValue, getKey, getVal, getTag helpers
• topKWithFractionalIndexBTree.ts: Update type signatures to use [K, T]

Test plan

• All existing db-ivm tests pass (267 tests)
• All existing db package tests pass (1718 tests)
• ORDER BY tests specifically verified

[changeset-bot]

🦋 Changeset detected

Latest commit: 97bd6c9

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

This PR includes changesets to release 14 packages

Name	Type
@tanstack/db-ivm	Patch
@tanstack/db	Patch
@tanstack/angular-db	Patch
@tanstack/db-collection-e2e	Patch
@tanstack/electric-db-collection	Patch
@tanstack/offline-transactions	Patch
@tanstack/powersync-db-collection	Patch
@tanstack/query-db-collection	Patch
@tanstack/react-db	Patch
@tanstack/rxdb-db-collection	Patch
@tanstack/solid-db	Patch
@tanstack/svelte-db	Patch
@tanstack/trailbase-db-collection	Patch
@tanstack/vue-db	Patch

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commit: 97bd6c9

[github-actions]

Size Change: 0 B

Total Size: 87.2 kB

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Size Change: 0 B

Total Size: 3.35 kB

ℹ️ View Unchanged

Filename	Size
./packages/react-db/dist/esm/index.js	225 B
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./packages/react-db/dist/esm/usePacedMutations.js	401 B

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[kevin-dp]

Way better to tie break on the key rather than a hash.
Make sure to fix the problem with the current tie-breaker though such that it correctly compares keys of different types (strings vs numbers).