update

src/llmUtil.jl

@@ -2,7 +2,7 @@ module llmUtil
 
 export formatLLMtext, extractthink, checkAgentResponse_JSON, clean_json_response,
         extract_column_metadata, generate_embedding_payloads, resolve_semantic_cluster,
-        harvest_entity_catalog, resolve_entity
+        harvest_entity_catalog, resolve_entity, harvest_db_undirected_schema_graph
 
 using UUIDs, JSON, Dates, DataFrames, StringDistances, Graphs, LibPQ
 using ..util
@@ -223,13 +223,35 @@ end
 
 
 
-"""
-    harvest_db_undirected_schema_graph(pg_conn_str::String)
+""" Harvest database schema as undirected graph from PostgreSQL.
 
-Connects to a PostgreSQL instance, queries its metadata catalogs, and returns:
-1. `g::SimpleDiGraph`: The structural graph where nodes are tables.
-2. `id_to_table::Dict{Int, String}`: Maps numerical node IDs to real table names.
-3. `table_to_id::Dict{String, Int}`: Maps table names back to graph node IDs.
+Extracts table structure and relationships from a PostgreSQL database by querying
+system catalogs to build a graph representation of tables and their relationships.
+
+# Arguments
+- `pg_conn_str::String`
+  PostgreSQL connection string in LibPQ format (e.g., "host=hostname port=5432 dbname=database user=username password=secret")
+
+# Return
+- `g::SimpleGraph`: An undirected graph where nodes represent tables and edges represent
+  relationships (foreign keys or shared ID column patterns).
+- `id_to_table::Dict{Int, String}`: Maps numerical node IDs (1..n) to actual table names.
+- `table_to_id::Dict{String, Int}`: Reverse mapping from table names to graph node IDs.
+
+# Details
+The function extracts schema information using two strategies:
+1. **Explicit Foreign Keys**: Queries `pg_constraint` for actual foreign key relationships
+2. **Fallback Name Matching**: Infers relationships from shared column naming patterns
+   (e.g., `seller_id`, `product_id` columns across tables)
+
+# Example
+```julia
+julia> using GeneralUtils
+julia> pg_conn_str = "host=localhost port=5432 dbname=winedb user=admin password=secret"
+julia> g, id_to_table, table_to_id = GeneralUtils.harvest_db_undirected_schema_graph(pg_conn_str)
+julia> vertices(g)
+10
+```
 """
 function harvest_db_undirected_schema_graph(pg_conn_str)   
   conn = LibPQ.Connection(pg_conn_str) 
@@ -292,7 +314,7 @@ function harvest_db_undirected_schema_graph(pg_conn_str)
           sharing_tables = gdf.table_name
           
           # Connect all tables that share this ID column
-          for i in 1:length(sharing_tables), j in (i+1):length(sharing_tables)
+          for i in eachindex(sharing_tables), j in (i+1):length(sharing_tables)
             t1 = sharing_tables[i]
             t2 = sharing_tables[j]