Vector dimensions mismatch in OpenSearch vector store using BedrockEmbeddings

Question

• I'm using a vector store that I've created in AWS OpenSearch serverless. It has one index that has below configurations:

- Engine: faiss
- Precision: Binary
- Dimensions: 1024
- Distance Type: hamming
- M: 16
- ef_construction: 16
- ef_search: 512

• What I want to do is use the vector store instance to add vectors to it and use similarity search to get the relevant documents.

• While trying to add the vectors, I didn't get any errors, but when checking it in dashboard, no vector is added. Also, while similarity search, an error is thrown, which I've put above (the query embedding is mysteriously 8192 dimensions whereas bedrock's titan model can only create embedding with 1024 dimensions max.)

• To debug, I tried to create embeddings with just using BedrockEmbeddings, and I verified that the created embedding was 1024 dimensions to be precise.

Example Code

        const embeddings = new BedrockEmbeddings({
            region: process.env.AWS_REGION,
            credentials: {
                accessKeyId: process.env.AWS_ACCESS_KEY_ID,
                secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY
            },
            model: 'amazon.titan-embed-text-v2:0'
        });

        const vectorStore = new OpenSearchVectorStore(embeddings, {
            client,
            indexName: 'bedrock-knowledge-base-default-index',
            vectorFieldName: 'bedrock-knowledge-base-default-vector',
            service: 'aoss',
            vectorSearchOptions: {
                engine: 'hnsw'
            }
        });

const doc = await vectorStore.similaritySearch('what do you know about poc?', 1);

Error Message and Stack Trace

error ResponseError: search_phase_execution_exception: [query_shard_exception] Reason: failed to create query: Query vector has invalid dimension: 8192. Dimension should be: 1024
    at onBody (/home/usr/Projects/backend/conversation/node_modules/@opensearch-project/opensearch/lib/Transport.js:426:23)
    at IncomingMessage.onEnd (/home/usr/Projects/backend/conversation/node_modules/@opensearch-project/opensearch/lib/Transport.js:341:11)
    at IncomingMessage.emit (node:events:531:35)
    at IncomingMessage.emit (node:domain:488:12)
    at endReadableNT (node:internal/streams/readable:1696:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21)

System Info

• Platform : Pop!_OS 22.04 LTS
• Node Version: 20.16.0
• langchain@0.3.11

Dependencies: @langchain/openai: >=0.1.0 <0.4.0 js-yaml: ^4.1.0 openapi-types: ^12.1.3 yaml: ^2.2.1
@langchain/textsplitters: >=0.0.0 <0.2.0 jsonpointer: ^5.0.1 p-retry: 4 zod-to-json-schema: ^3.22.3
js-tiktoken: ^1.0.12 langsmith: ^0.2.8 uuid: ^10.0.0 zod: ^3.22.4