What this category of data looks like
Urban gas sector policy and regulatory basis data is primarily sourced from official public documents and internal compliance materials published by the Ministry of Housing and Urban-Rural Development, provincial and municipal gas regulatory authorities, and urban investment groups. Data updates trigger when new policies are released or local detailed rules are revised. There is no fixed update cycle, but quarterly new additions remain consistent. Document types include normative documents, safety operation guidelines, business licensing guidelines, and more. Each document contains fields such as release document number, effective date, applicable region, and clause details. Individual document lengths range from hundreds to tens of thousands of characters.
What constraints do these characteristics impose on the vector model and indexing workflow
The variance in urban gas policy document lengths, structured metadata, and region-bound attributes create multiple constraints for the vector model and indexing process. The length gap between short Q&A guidelines and long normative documents requires chunking strategies tailored to different document types. This avoids overly fine-grained splitting that causes semantic fragmentation, or overly coarse splitting that loses key policy clauses. The presence of region and effective date fields requires retaining metadata tags during indexing. This enables subsequent recall to filter irrelevant results by region and time validity. The lack of a fixed update cycle requires an incremental indexing mechanism that can be triggered on demand. This avoids excessive system resource usage from full reindexing.
Configuration Settings
| Configuration Item | Recommended Setting | Rationale |
|---|---|---|
| Chunk Length | 800–1200 characters | Adapts to the range of urban gas policy document lengths, from hundreds to tens of thousands of characters, avoiding single-chunk semantic breaks or redundancy |
| Overlap Length | 100–200 characters | Compensates for semantic gaps at chunk boundaries, ensuring continuity of policy clauses |
| Similarity Threshold | 0.72–0.85 | Filters low-relevance recall results with similar phrasing in urban gas policies, matching the precision needs of policy Q&A |
| Single Recall Limit | Top 8 results | Controls total context length, adapting to the information density of policy Q&A |
| Reranking | Enabled | Optimizes the ranking of recall results, highlighting policy clauses directly relevant to the query |
maxToken | 3500–4000 tokens | Limits the total context length per round of Q&A, avoiding exceeding model processing limits |
Three Common Misconfigurations
- Scenario: After deploying FastGPT v4.17.0 locally, the automatic image indexing option does not appear when creating a new knowledge base. Cause: This feature requires a commercial-exclusive plugin, which is not enabled by default for local deployments.
- Scenario: Recall results include cross-regional urban gas policies that do not match the active service region. Cause: Region metadata tags were not retained during indexing, and region-based filtering recall rules were not configured.
- Scenario: Recall results for a single long policy document are fragmented, failing to cover complete clauses. Cause: Chunk length was set too small, causing semantic breaks when policy clauses are split.
How to Verify Proper Configuration
- Upload one urban gas policy document, check if the chunked results cover complete clauses with no obvious semantic breaks.
- Input a regionalized policy query, confirm that recall results only include policy documents from the corresponding region.
- Test uploading documents of different lengths, verify that the chunking strategy adapts to both long normative documents and short Q&A materials.
- Check the knowledge base indexing logs, confirm that incremental indexing can be triggered on demand, with no anomalies of full repeated indexing.
The values listed here are common starting points, and should be evaluated against the reader’s own samples.
Question material comes from public community discussions. Configuration values are common starting points and should be measured against your own samples. Verified on 2026-09-28.