column name can be on left or right in where conditions

weed/query/engine/engine.go

@@ -1210,18 +1210,56 @@ func (e *SQLEngine) buildPredicate(expr sqlparser.Expr) (func(*schema_pb.RecordV
 }
 
 // buildComparisonPredicate creates a predicate for comparison operations (=, <, >, etc.)
+// Handles column names on both left and right sides of the comparison
 func (e *SQLEngine) buildComparisonPredicate(expr *sqlparser.ComparisonExpr) (func(*schema_pb.RecordValue) bool, error) {
-	// Extract column name (left side)
-	colName, ok := expr.Left.(*sqlparser.ColName)
-	if !ok {
-		return nil, fmt.Errorf("unsupported comparison left side: %T", expr.Left)
+	var columnName string
+	var compareValue interface{}
+	var operator string
+
+	// Check if column is on the left side (normal case: column > value)
+	if colName, ok := expr.Left.(*sqlparser.ColName); ok {
+		columnName = colName.Name.String()
+		operator = expr.Operator
+
+		// Extract comparison value from right side
+		val, err := e.extractComparisonValue(expr.Right)
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract right-side value: %v", err)
+		}
+		compareValue = val
+
+	} else if colName, ok := expr.Right.(*sqlparser.ColName); ok {
+		// Column is on the right side (reversed case: value < column)
+		columnName = colName.Name.String()
+
+		// Reverse the operator when column is on right side
+		operator = e.reverseOperator(expr.Operator)
+
+		// Extract comparison value from left side
+		val, err := e.extractComparisonValue(expr.Left)
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract left-side value: %v", err)
+		}
+		compareValue = val
+
+	} else {
+		return nil, fmt.Errorf("no column name found in comparison expression, left: %T, right: %T", expr.Left, expr.Right)
 	}
 
-	columnName := colName.Name.String()
+	// Create predicate based on operator
+	return func(record *schema_pb.RecordValue) bool {
+		fieldValue, exists := record.Fields[columnName]
+		if !exists {
+			return false
+		}
 
-	// Extract comparison value (right side)
-	var compareValue interface{}
-	switch val := expr.Right.(type) {
+		return e.evaluateComparison(fieldValue, operator, compareValue)
+	}, nil
+}
+
+// extractComparisonValue extracts the comparison value from a SQL expression
+func (e *SQLEngine) extractComparisonValue(expr sqlparser.Expr) (interface{}, error) {
+	switch val := expr.(type) {
 	case *sqlparser.SQLVal:
 		switch val.Type {
 		case sqlparser.IntVal:
@@ -1229,9 +1267,9 @@ func (e *SQLEngine) buildComparisonPredicate(expr *sqlparser.ComparisonExpr) (fu
 			if err != nil {
 				return nil, err
 			}
-			compareValue = intVal
+			return intVal, nil
 		case sqlparser.StrVal:
-			compareValue = string(val.Val)
+			return string(val.Val), nil
 		default:
 			return nil, fmt.Errorf("unsupported SQL value type: %v", val.Type)
 		}
@@ -1253,22 +1291,10 @@ func (e *SQLEngine) buildComparisonPredicate(expr *sqlparser.ComparisonExpr) (fu
 				}
 			}
 		}
-		compareValue = inValues
+		return inValues, nil
 	default:
-		return nil, fmt.Errorf("unsupported comparison right side: %T", expr.Right)
+		return nil, fmt.Errorf("unsupported comparison value type: %T", expr)
 	}
-
-	// Create predicate based on operator
-	operator := expr.Operator
-
-	return func(record *schema_pb.RecordValue) bool {
-		fieldValue, exists := record.Fields[columnName]
-		if !exists {
-			return false
-		}
-
-		return e.evaluateComparison(fieldValue, operator, compareValue)
-	}, nil
 }
 
 // evaluateComparison performs the actual comparison