Vectorize Gotchas

Critical Warnings

Async Mutations

Insert/upsert/delete return immediately but vectors aren't queryable for 5-10 seconds.

Batch Size Limit

Workers API: 500 vectors max per call (undocumented, silently truncates)

// ✅ Chunk into 500
for (let i = 0; i < vectors.length; i += 500) {
  await env.VECTORIZE.upsert(vectors.slice(i, i + 500));
}

Metadata Truncation

returnMetadata: "indexed" returns only first 64 bytes of strings. Use "all" for complete metadata (but max topK drops to 20).

topK Limits

returnMetadata	returnValues	Max topK
`"none"` / `"indexed"`	`false`	100
`"all"`	any	20
any	`true`	20

Metadata Indexes First

Create BEFORE inserting - existing vectors not retroactively indexed.

# ✅ Create index FIRST
wrangler vectorize create-metadata-index my-index --property-name=category --type=string
wrangler vectorize insert my-index --file=data.ndjson

Index Config Immutable

Cannot change dimensions/metric after creation. Must create new index and migrate.

Limits (V2)

Resource	Limit
Vectors per index	10,000,000
Max dimensions	1536
Batch upsert (Workers)	500
Indexed string metadata	64 bytes
Metadata indexes	10
Namespaces	50,000 (paid) / 1,000 (free)

Common Mistakes

Wrong embedding shape: Extract result.data[0] from Workers AI
Metadata index after data: Re-upsert all vectors
Insert vs upsert: insert ignores duplicates, upsert overwrites
Not batching: Individual inserts ~1K/min, batched ~200K+/min

Troubleshooting

No results?

Wait 5-10s after insert
Check namespace spelling (case-sensitive)
Verify metadata index exists
Check dimension mismatch

Metadata filter not working?

Index must exist before data insert
Strings >64 bytes truncated
Use dot notation for nested: "product.category"

Model Dimensions

@cf/baai/bge-small-en-v1.5: 384
@cf/baai/bge-base-en-v1.5: 768
@cf/baai/bge-large-en-v1.5: 1024

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