fix: expression property mappings + CTE node expansion tests (#203)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: genezhang

src/clickhouse_query_generator/to_sql_query.rs

@@ -1153,16 +1153,38 @@ pub(crate) fn rewrite_expr_for_vlp(
             })
         }
 
-        RenderExpr::AggregateFnCall(agg) => RenderExpr::AggregateFnCall(AggregateFnCall {
-            name: agg.name.clone(),
-            args: agg
-                .args
-                .iter()
-                .map(|a| {
-                    rewrite_expr_for_vlp(a, start_alias, end_alias, path_variable, skip_start_alias)
-                })
-                .collect(),
-        }),
+        RenderExpr::AggregateFnCall(agg) => {
+            // COUNT(path_variable) → COUNT(*) since each row represents a path
+            if let Some(path_var) = path_variable {
+                if agg.args.len() == 1 && agg.name.to_lowercase() == "count" {
+                    if let RenderExpr::TableAlias(alias) = &agg.args[0] {
+                        if &alias.0 == path_var {
+                            log::info!("🔧 VLP path aggregate: count({}) → count(*)", path_var);
+                            return RenderExpr::AggregateFnCall(AggregateFnCall {
+                                name: agg.name.clone(),
+                                args: vec![RenderExpr::Star],
+                            });
+                        }
+                    }
+                }
+            }
+            RenderExpr::AggregateFnCall(AggregateFnCall {
+                name: agg.name.clone(),
+                args: agg
+                    .args
+                    .iter()
+                    .map(|a| {
+                        rewrite_expr_for_vlp(
+                            a,
+                            start_alias,
+                            end_alias,
+                            path_variable,
+                            skip_start_alias,
+                        )
+                    })
+                    .collect(),
+            })
+        }
 
         RenderExpr::ColumnAlias(ColumnAlias(alias_str))
             if path_variable.as_ref() == Some(alias_str) =>
@@ -1563,14 +1585,31 @@ fn rewrite_expr_for_fixed_path(
             })
         }
 
-        RenderExpr::AggregateFnCall(agg) => RenderExpr::AggregateFnCall(AggregateFnCall {
-            name: agg.name.clone(),
-            args: agg
-                .args
-                .iter()
-                .map(|a| rewrite_expr_for_fixed_path(a, path_variable, hop_count))
-                .collect(),
-        }),
+        RenderExpr::AggregateFnCall(agg) => {
+            // COUNT(path_variable) → COUNT(*) since each row represents a path
+            if agg.args.len() == 1 {
+                if let RenderExpr::TableAlias(alias) = &agg.args[0] {
+                    if alias.0 == *path_variable && agg.name.to_lowercase() == "count" {
+                        log::info!(
+                            "🔧 Fixed path aggregate: count({}) → count(*)",
+                            path_variable
+                        );
+                        return RenderExpr::AggregateFnCall(AggregateFnCall {
+                            name: agg.name.clone(),
+                            args: vec![RenderExpr::Star],
+                        });
+                    }
+                }
+            }
+            RenderExpr::AggregateFnCall(AggregateFnCall {
+                name: agg.name.clone(),
+                args: agg
+                    .args
+                    .iter()
+                    .map(|a| rewrite_expr_for_fixed_path(a, path_variable, hop_count))
+                    .collect(),
+            })
+        }
 
         // Leave other expressions unchanged
         other => other.clone(),

src/open_cypher_parser/use_clause.rs

@@ -1,6 +1,8 @@
 use nom::{
-    bytes::complete::{tag_no_case, take_while1},
+    branch::alt,
+    bytes::complete::{tag, tag_no_case, take_while1},
     error::context,
+    sequence::delimited,
     IResult, Parser,
 };
 
@@ -10,17 +12,20 @@ use super::{ast::UseClause, common::ws, errors::OpenCypherParsingError};
 /// Examples:
 ///   USE social_network
 ///   USE ecommerce
-///   USE mydb
+///   USE `my-database`
 pub fn parse_use_clause<'a>(
     input: &'a str,
 ) -> IResult<&'a str, UseClause<'a>, OpenCypherParsingError<'a>> {
     let (input, _) = ws(tag_no_case("USE")).parse(input)?;
 
     let (input, database_name) = context(
         "Error parsing database name in USE clause",
-        ws(take_while1(|c: char| {
-            c.is_alphanumeric() || c == '_' || c == '.'
-        })),
+        ws(alt((
+            // Backtick-quoted identifier: USE `my-database`
+            delimited(tag("`"), take_while1(|c: char| c != '`'), tag("`")),
+            // Unquoted identifier
+            take_while1(|c: char| c.is_alphanumeric() || c == '_' || c == '.'),
+        ))),
     )
     .parse(input)?;
 
@@ -92,6 +97,32 @@ mod tests {
         assert!(res.is_err(), "Should fail when database name is missing");
     }
 
+    #[test]
+    fn test_parse_use_clause_backtick_quoted() {
+        let input = "USE `my-database` MATCH (n) RETURN n";
+        let res = parse_use_clause(input);
+        match res {
+            Ok((remaining, use_clause)) => {
+                assert_eq!(use_clause.database_name, "my-database");
+                assert_eq!(remaining, "MATCH (n) RETURN n");
+            }
+            Err(e) => panic!("Failed to parse backtick-quoted USE clause: {:?}", e),
+        }
+    }
+
+    #[test]
+    fn test_parse_use_clause_backtick_with_special_chars() {
+        let input = "USE `zeek_logs` MATCH (n) RETURN n";
+        let res = parse_use_clause(input);
+        match res {
+            Ok((remaining, use_clause)) => {
+                assert_eq!(use_clause.database_name, "zeek_logs");
+                assert_eq!(remaining, "MATCH (n) RETURN n");
+            }
+            Err(e) => panic!("Failed to parse backtick-quoted USE clause: {:?}", e),
+        }
+    }
+
     #[test]
     fn test_parse_use_clause_numeric_start() {
         let input = "USE 123db";

src/query_planner/logical_plan/match_clause/helpers.rs

@@ -422,16 +422,15 @@ pub fn register_path_variable(
     );
 
     // Then register TableCtx for backward compatibility with code that uses alias_table_ctx_map
-    plan_ctx.insert_table_ctx(
+    let mut table_ctx = TableCtx::build(
         path_var.to_string(),
-        TableCtx::build(
-            path_var.to_string(),
-            None,   // Path variables don't have labels
-            vec![], // Path variables don't have properties
-            false,  // Not a relationship
-            true,   // Explicitly named by user
-        ),
+        None,   // Path variables don't have labels
+        vec![], // Path variables don't have properties
+        false,  // Not a relationship
+        true,   // Explicitly named by user
     );
+    table_ctx.set_is_path(true);
+    plan_ctx.insert_table_ctx(path_var.to_string(), table_ctx);
 
     log::info!(
         "📍 Registered path variable '{}' with TypedVariable::Path (start={}, end={}, bounds={:?})",

src/query_planner/optimizer/collect_unwind_elimination.rs

@@ -518,12 +518,24 @@ impl CollectUnwindElimination {
 
                                             // Add the source variable as a passthrough item so it's exported
                                             // (the UNWIND alias will be rewritten to reference this)
-                                            new_items.push(ProjectionItem {
-                                                expression: LogicalExpr::TableAlias(TableAlias(
-                                                    source.clone(),
-                                                )),
-                                                col_alias: Some(ColumnAlias(source.clone())),
-                                            });
+                                            // Only add if source isn't already in the remaining items
+                                            let source_already_present =
+                                                new_items.iter().any(|item| {
+                                                    match &item.expression {
+                                                        LogicalExpr::TableAlias(ta) => {
+                                                            ta.0 == source
+                                                        }
+                                                        _ => false,
+                                                    }
+                                                });
+                                            if !source_already_present {
+                                                new_items.push(ProjectionItem {
+                                                    expression: LogicalExpr::TableAlias(
+                                                        TableAlias(source.clone()),
+                                                    ),
+                                                    col_alias: Some(ColumnAlias(source.clone())),
+                                                });
+                                            }
 
                                             // Update exported aliases: remove collection, add source
                                             let mut new_exported_aliases: Vec<String> = with

src/query_planner/plan_ctx/table_ctx.rs

@@ -37,6 +37,8 @@ pub struct TableCtx {
     /// For relationships: the label of the connected to_node (target)
     /// Used to resolve polymorphic relationships
     to_node_label: Option<String>,
+    /// Whether this alias represents a path variable (from `MATCH p = ...`)
+    is_path: bool,
 }
 
 impl TableCtx {
@@ -63,6 +65,7 @@ impl TableCtx {
             cte_reference: None,
             from_node_label: None,
             to_node_label: None,
+            is_path: false,
         }
     }
 
@@ -108,6 +111,7 @@ impl TableCtx {
             cte_reference: Some(cte_name),
             from_node_label: None,
             to_node_label: None,
+            is_path: false,
         }
     }
 
@@ -135,6 +139,9 @@ impl TableCtx {
     /// Path variables have no label (None) and are not relationships.
     /// Anonymous nodes also have None labels, so we exclude aliases matching "t\d+" pattern.
     pub fn is_path_variable(&self) -> bool {
+        if self.is_path {
+            return true;
+        }
         if self.is_rel {
             return false;
         }
@@ -143,9 +150,6 @@ impl TableCtx {
         }
         // Computed/scalar aliases from WITH (e.g., `WITH size(...) AS cnt`)
         // have explicit_alias=true but no labels — they are NOT path variables.
-        // Note: Real path variables (e.g., `p` in `MATCH p = ...`) are also
-        // explicit_alias=true, but they are registered via define_path() directly
-        // in match_clause/traversal.rs, not through this heuristic.
         if self.explicit_alias {
             return false;
         }
@@ -160,6 +164,11 @@ impl TableCtx {
         true // No labels, not a relationship, not an anonymous node → path variable
     }
 
+    /// Mark this TableCtx as a path variable.
+    pub fn set_is_path(&mut self, val: bool) {
+        self.is_path = val;
+    }
+
     // ========================================================================
     // Label/Type Access
     // ========================================================================

src/render_plan/cte_generation.rs

@@ -9,6 +9,7 @@ use std::collections::HashMap;
 use crate::clickhouse_query_generator::variable_length_cte::WeightCteConfig;
 use crate::clickhouse_query_generator::NodeProperty;
 use crate::graph_catalog::config::Identifier;
+use crate::graph_catalog::expression_parser::PropertyValue;
 use crate::graph_catalog::graph_schema::GraphSchema;
 use crate::query_planner::logical_expr::LogicalExpr;
 use crate::query_planner::logical_plan::LogicalPlan;
@@ -783,6 +784,67 @@ pub fn map_property_to_column_with_relationship_context(
     Ok(column.raw().to_string())
 }
 
+/// Like `map_property_to_column_with_relationship_context` but preserves
+/// the `PropertyValue` variant (Column vs Expression). Use this when the
+/// caller needs to generate correct SQL for expression-based mappings.
+pub fn map_property_to_property_value(
+    property: &str,
+    node_label: &str,
+) -> Result<PropertyValue, String> {
+    let current_schema = crate::server::query_context::get_current_schema_with_fallback();
+    let schema = current_schema.as_ref().ok_or_else(|| {
+        format!(
+            "No schema available for property '{}' on node '{}'",
+            property, node_label
+        )
+    })?;
+
+    let node_schema = schema
+        .all_node_schemas()
+        .get(node_label)
+        .ok_or_else(|| format!("Node label '{}' not found in schema", node_label))?;
+
+    node_schema
+        .property_mappings
+        .get(property)
+        .cloned()
+        .ok_or_else(|| {
+            format!(
+                "Property '{}' not found for node label '{}'",
+                property, node_label
+            )
+        })
+}
+
+/// Like `map_property_to_property_value` but for relationship properties.
+pub fn map_rel_property_to_property_value(
+    property: &str,
+    relationship_type: &str,
+) -> Result<PropertyValue, String> {
+    let current_schema = crate::server::query_context::get_current_schema_with_fallback();
+    let schema = current_schema.as_ref().ok_or_else(|| {
+        format!(
+            "No schema available for property '{}' on rel '{}'",
+            property, relationship_type
+        )
+    })?;
+
+    let rel_schema = schema
+        .get_rel_schema(relationship_type)
+        .map_err(|e| format!("Relationship type '{}' not found: {}", relationship_type, e))?;
+
+    rel_schema
+        .property_mappings
+        .get(property)
+        .cloned()
+        .ok_or_else(|| {
+            format!(
+                "Property '{}' not found for relationship type '{}'",
+                property, relationship_type
+            )
+        })
+}
+
 /// Map a relationship property to its corresponding column name in the schema.
 /// This is the relationship equivalent of map_property_to_column_with_schema.
 ///