What causes "failed to get existing posting metadata for posting %d" in weaviate/weaviate?

Inspect the wrapped inner error for the bucket-level cause.

failed to get existing posting metadata for posting %d

Error message

failed to get existing posting metadata for posting %d

What it means

SetVectorIDs reads the existing packed posting metadata from the bucket to skip no-op writes; this error wraps a bucket.Get failure other than ErrPostingNotFound when updating the vector-ID list of a posting. It means the posting-metadata bucket could not be read (I/O or internal error), so the update is aborted. ErrPostingNotFound is deliberately tolerated and does NOT produce this error.

Source

Thrown at adapters/repos/db/vector/hfresh/posting_map.go:122

func (v *PostingMap) SetVectorIDs(ctx context.Context, postingID uint64, posting Posting) error {
	if len(posting) == 0 {
		err := v.bucket.Delete(ctx, postingID)
		if err != nil {
			return err
		}
		v.deleteSlot(postingID)
		return nil
	}

	var pm PackedPostingMetadata
	for _, vector := range posting {
		pm = pm.AddVector(vector.ID())
	}
	pm = pm.Compact()

	existing, err := v.bucket.Get(ctx, postingID)
	if err != nil && !errors.Is(err, ErrPostingNotFound) {
		return errors.Wrapf(err, "failed to get existing posting metadata for posting %d", postingID)
	}
	if err == nil && bytes.Equal(pm, existing) {
		// no change, skip the update
		v.setSlot(postingID, pm)
		return nil
	}

	// store the updated posting metadata on disk and update the in-memory cache
	err = v.bucket.Set(ctx, postingID, pm)
	if err != nil {
		return err
	}

	v.setSlot(postingID, pm)

	return nil
}

View on GitHub (pinned to 75aa4b6d11)

Solutions

Inspect the wrapped inner error for the bucket-level cause.
Check disk health and shard directory integrity.
Retry the operation; SetVectorIDs assumes the caller holds the posting lock and is idempotent.
If persistent, restore the shard from backup or recreate the index.

Defensive patterns

Strategy: try-catch

Try / catch

if err := pm.SetVectorIDs(ctx, postingID, posting); err != nil {
    // tolerate only ErrPostingNotFound-shaped absence; surface real I/O errors
    if !errors.Is(err, ErrPostingNotFound) {
        logger.Errorf("posting %d metadata update failed: %v", postingID, err)
    }
}

Prevention

Distinguish ErrPostingNotFound (benign) from real bucket errors.
Run filesystem checks after unclean shutdowns.
Hold the posting lock as required before calling SetVectorIDs.
Monitor underlying LSM bucket error rates.

When it happens

Trigger: setPostingVectorIDs (called from doMerge and merge paths) -> PostingMap.SetVectorIDs with a non-empty posting, where v.bucket.Get(ctx, postingID) returns a real error (not ErrPostingNotFound).

Common situations: Disk I/O errors, LSM bucket corruption, or shutdown racing with a maintenance write.

Related errors

AI-assisted analysis of weaviate/weaviate@75aa4b6d11 (2026-09-04). Data as JSON: /api/errors/f115c42252a6fb1f. Report an issue: GitHub.