TiDB vector index restrictions: TiFlash required, cosine and L2 only
TiDB vector index restrictions: TiFlash required, cosine and L2 only. TiFlash nodes must be deployed in the cluster first; the feature relies on TiFlash replicas, so set TIFLASH REPLICA 1 before creating the index unless it is in CREATE TABLE. Use when hitting this exact issue with TiDB vector index restrictions. Not for unrelated errors or different features.
TL;DR
TiFlash nodes must be deployed in the cluster first; the feature relies on TiFlash replicas, so set TIFLASH REPLICA 1 before creating the index unless it is in CREATE TABLE. Only VECCOSINEDISTANCE and VECL2DISTANCE are indexable.
Fix
TiFlash nodes must be deployed in the cluster first; the feature relies on TiFlash replicas, so set TIFLASH REPLICA 1 before creating the index unless it is in CREATE TABLE. Expected: You get the expected result; the problem is gone.
When to use
- You are setting up or using this TiDB vector index restrictions feature.
- The symptom matches: TiFlash required, cosine and L2 only.
When NOT to use
- Unrelated TiDB vector index restrictions issues (different feature, different failure).
- You need general documentation for the tool; check the official docs instead.
Compatibility
Reported against TiDB vector index restrictions (mentions v8.4, v8.5). Source: https://docs.pingcap.com/tidb/dev/vector-search-index/.
Variant phrasings
TiFlash required, cosine and L2 only
Why it happens
TiDB vector search indexes have hard restrictions. Hitting one produces a confusing failure far from the real cause.
Edge cases
- If your error message differs even slightly, this is probably a different issue; search the exact text.
- Behavior can change between releases; the linked source reflects the versions above.
- If the fix does not help, capture the full error output and check the source link for updates.
Source
https://docs.pingcap.com/tidb/dev/vector-search-index/