Bug Report: when using OceanBase as vector store, metadata filtering is not supported

[hsiong]

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Dify version

v1.1.2

Cloud or Self Hosted

Self Hosted (Source)

Steps to reproduce

1. change VECTOR_STORE from weaviate to oceanbase
2. add a file to the knowledge base
3. attach metadata to this file, for example: 'area=1234'
4. retrieve oceanbase with metadata filtering like 'area contains 1234'

✔️ Expected Behavior

Retrive knowledge with metadata filtering as below:

❌ Actual Behavior

Retrive nothing