Milvus fails to insert documents if metadata is longer

[florianleimer]

Checked other resources

• This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
• I added a very descriptive title to this issue.
• I searched the LangChain.js documentation with the integrated search.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in LangChain.js rather than my code.
• The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package).

Example Code

import { Milvus } from '@langchain/community/vectorstores/milvus';
import { Document } from '@langchain/core/documents';
import { OpenAIEmbeddings } from '@langchain/openai';

const vectorStore = await Milvus.fromDocuments(
  [
    new Document({
      metadata: {
        description: 'Short description',
      },
      pageContent: 'Lorem ipsum dolor sit amet, consetetur sadipscing elitr',
    }),
  ],
  new OpenAIEmbeddings(),
  {
    collectionName: 'goldel_escher_bach',
  },
);

await vectorStore.addDocuments([
  new Document({
    metadata: {
      description: 'This is a longer description',
    },
    pageContent: 'Lorem ipsum dolor sit amet, consetetur sadipscing elitr',
  }),
]);

Error Message and Stack Trace (if applicable)

file:///var/www/html/node_modules/@langchain/community/dist/vectorstores/milvus.js:171
                if (insertResp.status.error_code !== ErrorCode.SUCCESS) throw new Error(`Error ${this.autoId ? "inserting" : "upserting"} data: ${JSON.stringify(insertResp)}`);
                                                                              ^

Error: Error inserting data: {"succ_index":[],"err_index":[0],"status":{"extra_info":{},"error_code":"IllegalArgument","reason":"length of varchar field description exceeds max length, row number: 0, length: 28, max length: 17: invalid parameter","code":1100,"retriable":false,"detail":"length of varchar field description exceeds max length, row number: 0, length: 28, max length: 17: invalid parameter"},"IDs":null,"acknowledged":false,"insert_cnt":"0","delete_cnt":"0","upsert_cnt":"0","timestamp":"0"}
    at Milvus.addVectors (file:///var/www/html/node_modules/@langchain/community/dist/vectorstores/milvus.js:171:65)
    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)
    at async Milvus.addDocuments (file:///var/www/html/node_modules/@langchain/community/dist/vectorstores/milvus.js:119:3)
    at async file:///var/www/html/src/test.ts:20:1

Description

• After I have inserted some documents, the next insert into the same collection fails, because one metadata field is longer than the longest one from before.
• This is because the metadata field length was calculated on the first insert based on the longest value, but is not updated on a reinsert.

System Info

@langchain/community v1.1.14
langchain v1.2.24
Node.js v24.13.0
MacOS 26