What Happens to a Vector Index When Documents Change?

A vector index needs a lifecycle for revisions, deletions, and model changes. Storing a new vector does not automatically remove every old passage, update every citation, or invalidate cached answers.

Design the record identity before the first bulk import. A stable document ID, revision, chunk identity, and source locator make later changes traceable. Without them, a reindex can leave several plausible versions of the same answer.

Separate source identity from chunk identity

A document is a source object. Its chunks are derived representations. If a revision changes paragraph boundaries, a chunk's position may move even when much of the content stays the same.

Retain the document revision associated with each derived record. Choose whether a replacement swaps all chunks or updates selected ones, and make that policy observable. The application should be able to list which representation currently answers for a source.

Define the transition between versions

A replacement can be prepared before it becomes active. This avoids a period where half the new document and half the old one supply answers. The exact mechanism depends on the database, but the application still needs an accepted-version rule.

A late retry of an older revision must not displace a newer one. Compare source version information or another monotonic event boundary before accepting the write. Arrival time alone is not a reliable source-of-truth order.

Treat deletion as a path through derived data

Remove or exclude the relevant index records, source fetch path, and application caches according to the promised behavior. Check that scheduled syncs and retry queues will not restore the deleted source.

An empty nearest-neighbor result is only evidence about that query. It does not prove all copies disappeared. The memory lifecycle guide explains how to test the broader operation without overstating its scope.

Plan model migrations as index migrations

Changing the embedding model can require rebuilding document vectors and changing query preprocessing together. Keep the model revision in the index metadata and compare the new representation with the old under a fixed question set.

During a parallel migration, budget for both indexes and a rollback route. Preserve source IDs so differences in ranked results can be explained instead of treating the migration as an opaque score change.

For a managed ingestion path, review Supermemory's document operations and test a document revision in the console-backed workflow. Verify readiness and retrieval after the revision before expanding to the full corpus.