Files
ragflow/internal/engine/serenedb/serenedb.go
deadtrickster 197b142cef feat(serenedb): add SereneDB doc-store engine (Go + Python connectors) (#17375)
## What

Adds [**SereneDB**](https://serenedb.com) as a selectable doc-store
engine on **both** RAGFlow paths:
- the **Go** `DocEngine` (`internal/engine/serenedb`), alongside
Elasticsearch and Infinity;
- the **Python** `DocStoreConnection` (`rag/utils/serenedb_conn.py`) +
`DOC_ENGINE=serenedb` registration.

SereneDB is a PostgreSQL-wire engine (DuckDB execution) whose single
inverted index carries **both** a scored text column (`@@`, BM25) and an
IVF vector column (`<#>`, inner product), so hybrid search is one SQL
statement. The Go engine connects with `database/sql` + `lib/pq`
(already a dependency, no new module); the Python connector uses
psycopg2 (already a dependency).

## Storage model

One table per tenant with `kb_id` as a filter column - the
**Elasticsearch / OceanBase** model, not Infinity's per-dataset tables.
This keeps BM25 statistics (IDF, avgdl) computed over the whole tenant
corpus (global IDF). Both connectors use this identical layout, so they
are storage- and retrieval-compatible: `hybrid` proxy routing and
Python↔Go switching are safe. On the Python side the connector is wired
as OceanBase's plain-SQL sibling (chunk_data JSON metadata, inline chunk
vectors, verbatim ES field names); the ES tokenizer path is unchanged.
Metadata stays one table per tenant (`ragflow_doc_meta_<tenant>`).

The query shapes mirror the Python connector, including the five
empirically-found landmines: the scored dictionary needs `frequency +
norm` (else `BM25()` silently returns 0.0), the `@@` query is the
tokenized query, the scored lexical branch matches one column, vectors
use an L2-normalized shadow column with `ip`/`sq8`, and the similarity
threshold goes directly in the ANN scan's `WHERE`. **Minimum engine
version: SereneDB 26.07.4.**

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
2026-08-04 14:16:39 +08:00

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//
// Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Package serenedb implements the doc-store DocEngine backed by SereneDB, a
// PostgreSQL-wire engine whose single inverted index carries both a scored
// text column (@@, BM25) and an IVF vector column (<#>, inner product), so
// hybrid search is one SQL statement. It connects with database/sql + lib/pq
// and emits SQL directly; the query shapes mirror the Python
// SereneDBConnection (rag/utils/serenedb_conn.py) that reached Elasticsearch
// retrieval parity.
//
// Table layout follows the Elasticsearch/OceanBase model: one chunk table per
// tenant (the index name) with kb_id as a filter column, so BM25 statistics are
// computed over the whole tenant corpus. Metadata is one table per tenant
// (ragflow_doc_meta_{tenantID}).
//
// Minimum engine version: SereneDB 26.07.4. The vector-branch and fusion
// queries use the natural forms that rely on the 26.07.4 fixes for the
// vector-op predicate in an ANN scan's WHERE and the multi-reference index
// CTE; on earlier builds both silently returned empty.
package serenedb