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Add comprehensive column parsing capabilities to parser_tools extension
- Implement parse_columns table function for extracting column references from SQL queries - Support schema-qualified column references (schema.table.column.field) - Handle nested struct field access with full path resolution - Track column usage context (select, where, function_arg, order_by, etc.) - Provide expression_identifiers showing all column paths in complex expressions - Include selected_name for output column tracking and alias analysis - Enable complete SQL dependency analysis alongside existing function and table parsing Features: - Individual column reference extraction with context tracking - Complex expression analysis with dependency mapping - Alias chain support for SELECT clause analysis - Nested struct field navigation (my_schema.users.profile.address.city) - Function argument column tracking - NULL values for missing data instead of empty strings 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <[email protected]>
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‎CMakeLists.txt‎

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@@ -14,6 +14,7 @@ set(EXTENSION_SOURCES
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src/parse_tables.cpp
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src/parse_where.cpp
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src/parse_functions.cpp
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src/parse_columns.cpp
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)
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build_static_extension(${TARGET_NAME} ${EXTENSION_SOURCES})

‎src/include/parse_columns.hpp‎

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#pragma once
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#include "duckdb.hpp"
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#include <string>
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#include <vector>
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namespace duckdb {
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// Forward declarations
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class DatabaseInstance;
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struct ColumnResult {
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vector<vector<string>> expression_identifiers; // All identifiers in expression
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string table_schema; // NULL for aliases, schema name for table columns
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string table_name; // NULL for aliases, table name for table columns
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string column_name; // Column name (for single column refs), NULL for complex expressions
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string context; // Context where column appears (select, where, function_arg, etc.)
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string expression; // Full expression text
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string selected_name; // NULL for input columns, output column name for SELECT items
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};
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void RegisterParseColumnsFunction(DatabaseInstance &db);
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void RegisterParseColumnScalarFunction(DatabaseInstance &db);
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} // namespace duckdb

‎src/parse_columns.cpp‎

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#include "parse_columns.hpp"
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#include "duckdb.hpp"
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#include "duckdb/parser/parser.hpp"
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#include "duckdb/parser/statement/select_statement.hpp"
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#include "duckdb/parser/query_node/select_node.hpp"
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#include "duckdb/parser/expression/columnref_expression.hpp"
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#include "duckdb/parser/parsed_expression_iterator.hpp"
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#include "duckdb/parser/result_modifier.hpp"
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#include "duckdb/main/extension_util.hpp"
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namespace duckdb {
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enum class ColumnContext {
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Select,
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Where,
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Having,
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OrderBy,
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GroupBy,
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Join,
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FunctionArg,
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Window,
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Nested
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};
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inline const char *ToString(ColumnContext context) {
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switch (context) {
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case ColumnContext::Select: return "select";
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case ColumnContext::Where: return "where";
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case ColumnContext::Having: return "having";
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case ColumnContext::OrderBy: return "order_by";
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case ColumnContext::GroupBy: return "group_by";
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case ColumnContext::Join: return "join";
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case ColumnContext::FunctionArg: return "function_arg";
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case ColumnContext::Window: return "window";
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case ColumnContext::Nested: return "nested";
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default: return "unknown";
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}
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}
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struct ParseColumnsState : public GlobalTableFunctionState {
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idx_t row = 0;
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vector<ColumnResult> results;
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};
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struct ParseColumnsBindData : public TableFunctionData {
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string sql;
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};
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// Helper function to extract schema, table, and column from column_names vector
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static void ExtractTableInfo(const vector<string> &column_names,
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string &table_schema, string &table_name, string &column_name) {
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if (column_names.empty()) {
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return;
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}
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// For now, assume simple heuristic:
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// - If 3+ elements: first could be schema, second table, third+ column path
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// - If 2 elements: first table, second+ column path
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// - If 1 element: unqualified column
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if (column_names.size() >= 3) {
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// Assume schema.table.column format
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table_schema = column_names[0];
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table_name = column_names[1];
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column_name = column_names[2];
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} else if (column_names.size() == 2) {
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// Assume table.column format
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table_schema = "main"; // Default schema
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table_name = column_names[0];
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column_name = column_names[1];
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} else {
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// Unqualified column - could be table column or alias
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table_schema = ""; // Will be set to NULL
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table_name = ""; // Will be set to NULL
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column_name = column_names[0];
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}
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}
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// Helper function to convert vector<string> to a readable expression string
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static string VectorToString(const vector<string> &vec) {
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if (vec.empty()) {
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return "";
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}
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string result = vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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result += "." + vec[i];
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}
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return result;
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}
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// Helper function to serialize expression_identifiers as JSON-like string
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static string SerializeExpressionIdentifiers(const vector<vector<string>> &identifiers) {
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if (identifiers.empty()) {
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return "[]";
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}
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string result = "[";
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for (size_t i = 0; i < identifiers.size(); i++) {
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if (i > 0) result += ",";
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result += "[";
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for (size_t j = 0; j < identifiers[i].size(); j++) {
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if (j > 0) result += ",";
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result += "\"" + identifiers[i][j] + "\"";
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}
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result += "]";
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}
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result += "]";
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return result;
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}
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// Recursive function to extract column references from expressions
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static void ExtractFromExpression(const ParsedExpression &expr,
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vector<ColumnResult> &results,
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ColumnContext context,
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const string &selected_name = "") {
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if (expr.expression_class == ExpressionClass::COLUMN_REF) {
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auto &col_ref = (ColumnRefExpression &)expr;
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string table_schema, table_name, column_name;
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ExtractTableInfo(col_ref.column_names, table_schema, table_name, column_name);
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// Convert empty strings to NULLs for consistency
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if (table_schema.empty()) table_schema = "";
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if (table_name.empty()) table_name = "";
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vector<vector<string>> expr_ids = {col_ref.column_names};
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results.push_back(ColumnResult{
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expr_ids, // expression_identifiers
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table_schema.empty() ? "" : table_schema,
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table_name.empty() ? "" : table_name,
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column_name,
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ToString(context),
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VectorToString(col_ref.column_names),
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selected_name.empty() ? "" : selected_name
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});
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} else {
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// For non-column expressions, continue traversing to find nested column references
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ParsedExpressionIterator::EnumerateChildren(expr, [&](const ParsedExpression &child) {
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ExtractFromExpression(child, results, ColumnContext::FunctionArg);
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});
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}
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}
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// Helper function to collect all identifiers from an expression recursively
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static void CollectExpressionIdentifiers(const ParsedExpression &expr,
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vector<vector<string>> &all_identifiers) {
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if (expr.expression_class == ExpressionClass::COLUMN_REF) {
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auto &col_ref = (ColumnRefExpression &)expr;
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all_identifiers.push_back(col_ref.column_names);
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} else {
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ParsedExpressionIterator::EnumerateChildren(expr, [&](const ParsedExpression &child) {
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CollectExpressionIdentifiers(child, all_identifiers);
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});
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}
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}
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// Extract columns from SELECT node
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static void ExtractFromSelectNode(const SelectNode &select_node, vector<ColumnResult> &results) {
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// Extract from SELECT list (output columns)
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for (const auto &select_item : select_node.select_list) {
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string selected_name = select_item->alias.empty() ? "" : select_item->alias;
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// If no explicit alias, derive from expression
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if (selected_name.empty() && select_item->expression_class == ExpressionClass::COLUMN_REF) {
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auto &col_ref = (ColumnRefExpression &)*select_item;
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selected_name = col_ref.GetColumnName();
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}
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// First extract individual column references
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ExtractFromExpression(*select_item, results, ColumnContext::Select);
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// Then add the output column entry if it's a complex expression
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vector<vector<string>> all_identifiers;
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CollectExpressionIdentifiers(*select_item, all_identifiers);
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if (all_identifiers.size() > 1 || (all_identifiers.size() == 1 && !select_item->alias.empty())) {
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// Complex expression or aliased column - add output entry
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results.push_back(ColumnResult{
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all_identifiers,
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"", // table_schema
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"", // table_name
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"", // column_name
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ToString(ColumnContext::Select),
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select_item->ToString(),
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selected_name.empty() ? "" : selected_name
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});
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}
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}
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// Extract from WHERE clause
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if (select_node.where_clause) {
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ExtractFromExpression(*select_node.where_clause, results, ColumnContext::Where);
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}
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// Extract from GROUP BY clause
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for (const auto &group_expr : select_node.groups.group_expressions) {
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ExtractFromExpression(*group_expr, results, ColumnContext::GroupBy);
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}
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// Extract from HAVING clause
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if (select_node.having) {
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ExtractFromExpression(*select_node.having, results, ColumnContext::Having);
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}
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// Extract from ORDER BY clause
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for (const auto &modifier : select_node.modifiers) {
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if (modifier->type == ResultModifierType::ORDER_MODIFIER) {
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auto &order_modifier = (OrderModifier &)*modifier;
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for (const auto &order_term : order_modifier.orders) {
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ExtractFromExpression(*order_term.expression, results, ColumnContext::OrderBy);
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}
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}
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}
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}
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// BIND function: runs during query planning to decide output schema
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static unique_ptr<FunctionData> ParseColumnsBind(ClientContext &context, TableFunctionBindInput &input,
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vector<LogicalType> &return_types, vector<string> &names) {
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string sql_input = StringValue::Get(input.inputs[0]);
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// Define output schema - simplified for initial implementation
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return_types = {
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LogicalType::VARCHAR, // expression_identifiers (as JSON-like string for now)
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LogicalType::VARCHAR, // table_schema
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LogicalType::VARCHAR, // table_name
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LogicalType::VARCHAR, // column_name
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LogicalType::VARCHAR, // context
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LogicalType::VARCHAR, // expression
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LogicalType::VARCHAR // selected_name
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};
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names = {"expression_identifiers", "table_schema", "table_name", "column_name",
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"context", "expression", "selected_name"};
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auto result = make_uniq<ParseColumnsBindData>();
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result->sql = sql_input;
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return std::move(result);
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}
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// INIT function: runs before table function execution
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static unique_ptr<GlobalTableFunctionState> ParseColumnsInit(ClientContext &context,
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TableFunctionInitInput &input) {
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return make_uniq<ParseColumnsState>();
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}
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// Main parsing function
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static void ParseColumnsFunction(ClientContext &context, TableFunctionInput &data_p, DataChunk &output) {
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auto &bind_data = (ParseColumnsBindData &)*data_p.bind_data;
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auto &state = (ParseColumnsState &)*data_p.global_state;
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if (state.row == 0) {
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// Parse the SQL statement
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Parser parser;
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parser.ParseQuery(bind_data.sql);
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if (parser.statements.empty()) {
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return;
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}
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// Process each statement
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for (const auto &statement : parser.statements) {
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if (statement->type == StatementType::SELECT_STATEMENT) {
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auto &select_stmt = (SelectStatement &)*statement;
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auto &select_node = (SelectNode &)*select_stmt.node;
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ExtractFromSelectNode(select_node, state.results);
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}
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}
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}
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// Output results
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idx_t count = 0;
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while (state.row < state.results.size() && count < STANDARD_VECTOR_SIZE) {
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const auto &result = state.results[state.row];
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output.data[0].SetValue(count, Value(SerializeExpressionIdentifiers(result.expression_identifiers)));
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output.data[1].SetValue(count, result.table_schema.empty() ? Value() : Value(result.table_schema));
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output.data[2].SetValue(count, result.table_name.empty() ? Value() : Value(result.table_name));
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output.data[3].SetValue(count, result.column_name.empty() ? Value() : Value(result.column_name));
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output.data[4].SetValue(count, Value(result.context));
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output.data[5].SetValue(count, Value(result.expression));
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output.data[6].SetValue(count, result.selected_name.empty() ? Value() : Value(result.selected_name));
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state.row++;
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count++;
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}
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output.SetCardinality(count);
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}
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void RegisterParseColumnsFunction(DatabaseInstance &db) {
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TableFunction parse_columns("parse_columns", {LogicalType::VARCHAR}, ParseColumnsFunction, ParseColumnsBind, ParseColumnsInit);
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ExtensionUtil::RegisterFunction(db, parse_columns);
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}
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void RegisterParseColumnScalarFunction(DatabaseInstance &db) {
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// TODO: Implement scalar version similar to parse_function_names
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}
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} // namespace duckdb

‎src/parser_tools_extension.cpp‎

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#include "parse_tables.hpp"
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#include "parse_where.hpp"
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#include "parse_functions.hpp"
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#include "parse_columns.hpp"
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#include "duckdb.hpp"
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#include "duckdb/common/exception.hpp"
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#include "duckdb/common/string_util.hpp"
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RegisterParseWhereDetailedFunction(instance);
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RegisterParseFunctionsFunction(instance);
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RegisterParseFunctionScalarFunction(instance);
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RegisterParseColumnsFunction(instance);
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RegisterParseColumnScalarFunction(instance);
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}
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void ParserToolsExtension::Load(DuckDB &db) {

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