What the data for this category looks like
Expressway operation business data comes from toll settlement systems, road administration operation archives, official business handling manuals, toll pricing documents, and on-site disposal records. Two update schedules apply: Toll standards and traffic policies update quarterly or when policy is released. On-site disposal procedures and handling guides update annually or when processes adjust. Most individual documents are structured or semi-structured, containing fields such as vehicle type classification, billing unit, handling time limit, and material list. Some on-site records are unstructured text.
Constraints on knowledge base retrieval and recall from these characteristics
Structured toll pricing documents require precise matching of keyword fields like vehicle type and billing standards to avoid result deviations from fuzzy recall. Unstructured on-site disposal records have wide variations in text length, which reduces consistency of vector recall after chunking. Data updated per policy nodes must be synchronized to the knowledge base, otherwise outdated toll standards or handling rules may be recalled. Inconsistent units across multiple data sources—such as yuan per trip and yuan per kilometer for billing units—interfere with semantic matching during retrieval. Business handling process documents include fixed step sequences. Retrieval must retain this process order to avoid disrupting actual handling logic.
How to configure settings
This document uses FastGPT v4.17.0 configuration logic as its basis.
| Configuration Item | Recommended Setting | Rationale |
|---|---|---|
similarity | 0.72–0.85 | Expressway business keywords are mostly technical terms. A low threshold recalls irrelevant road administration records, while a high threshold misses correct process steps |
limit | Top 8 results | Most business handling processes include 5-7 steps. Too many recalled results exceed context window limits, while too few fail to cover all alternative solutions |
searchMode | vector+keyword | Balances structured field matching and semantic recall, adapting to business data with both pricing fields and process text |
usingReRank | Enabled, re-rank top 5 results | Unstructured on-site records have small differences in semantic similarity. Re-ranking filters out recall results with semantic deviations |
datasetSearchUsingExtensionQuery | Enabled | Business handling questions often use colloquial phrasing, such as "what materials are needed for ETC handling". Optimized extended queries match standard terminology in official documents |
collectionIds | Bind three dedicated knowledge base collections: toll business, road administration business, and handling guides | Divide collections by business module to prevent cross-category data from reducing retrieval accuracy |
Three Common Configuration Mistakes
- Phenomenon: Retrieving toll price quotes takes more than 30 seconds, and the interface displays a request timeout status code. Cause: Knowledge base collections are not divided by business module. Retrieval scans all irrelevant full data, leading to an overly long retrieval chain.
- Phenomenon: The same business question has matching results in two bound knowledge bases, but only one answer is returned. Cause: Multi-result merging logic is not configured. The default setting only returns a single result with the highest similarity, without implementing weight distribution and multi-answer display.
- Phenomenon: Recalled business handling process steps are out of order, which does not conform to actual handling logic. Cause:
usingReRankis not enabled, or the re-ranking logic does not retain the step sequence characteristics of the original document. The similarity ranking disrupts the process structure.
How to Verify Correct Configuration
- Manually input a high-frequency business question, such as "passenger car toll standards", and check if recalled results include correct vehicle type classification and billing rules.
- View the retrieval log to confirm only the knowledge base collections corresponding to the bound
collectionIdsare scanned, with no retrieval records for cross-module data. - Test a colloquial question, such as "what materials are needed for ETC handling", and confirm the extended query generated by
datasetSearchUsingExtensionQuerymatches standard terminology in official documents. - Adjust the
similaritythreshold, observe changes in the number of recalled results, and confirm the threshold value meets the matching accuracy requirements of business keywords.
The values given are common starting points and should be measured 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.