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Issue Analysis: Zero Results from List Tables Command ​

Problem Statement ​

The hana_tables (and similar list commands) returns zero results when called through the MCP server.

Root Cause ​

The issue is not with the **CURRENT_SCHEMA** transformation logic, which works correctly. The actual problem is:

Missing database connection configuration ​

The hana-cli tools require a default-env.json file (or equivalent environment configuration) containing SAP HANA connection credentials. Without this configuration:

  1. The connection is created but with undefined options
  2. Database queries execute but fail silently
  3. No results are returned, appearing as "zero results"

Technical Details ​

What Works ✓ ​

  • The **CURRENT_SCHEMA** placeholder replacement logic (in utils/database/databaseInspect.js)
  • The default parameter handling in the MCP server
  • The SQL query construction
  • The command execution flow

What Was Missing ✗ ​

  • Clear error messaging when database connection is not configured
  • Validation that connection credentials are present before executing queries
  • Documentation about the connection setup requirement

Solution Implemented ​

1. Enhanced Error Handling ​

Added validation in utils/base.js to check for valid connection configuration:

javascript
// Validate that we have a proper connection configuration
if (!this.options || !this.options.hana || !this.options.hana.host) {
    throw new Error('No valid database connection configuration found. Please create a default-env.json file or set up environment variables.')
}

2. Schema Validation ​

Added check in utils/database/databaseInspect.js to ensure schema is not empty:

javascript
// Validate schema is not empty
if (!schema1 || schema1.trim() === '') {
    throw new Error('Unable to determine current schema. Please check your database connection configuration.')
}

3. Debug Logging ​

Enhanced the MCP server with debug logging to help diagnose issues:

typescript
if (args.debug) {
    console.error('[DEBUG] hana_tables args:', JSON.stringify(args, null, 2));
    console.error('[DEBUG] Calling tables.default with:', JSON.stringify(tableArgs, null, 2));
    console.error('[DEBUG] Result type:', typeof result);
}

4. Documentation ​

Created comprehensive troubleshooting guide: mcp-server/TROUBLESHOOTING.md

How to Fix for Users ​

Users experiencing zero results should:

  1. Set up database connection using one of these methods:

    bash
    # Method 1: Via service key (recommended)
hana-cli serviceKey -i <instance-name> -k <key-name>

# Method 2: Interactive setup
hana-cli connect

  2. Verify connection:

    bash
    hana-cli status

  3. Check configuration file exists:

    • default-env.json should be in the project root
    • Should contain valid HANA credentials

Testing ​

All improvements have been tested:

  • ✓ Error handling with missing configuration
  • ✓ Proper error messages guide users to solution
  • ✓ Schema transformation logic remains functional
  • ✓ Debug mode provides diagnostic information

Files Modified ​

  1. utils/base.js - Added connection validation
  2. utils/database/databaseInspect.js - Added schema validation
  3. mcp-server/src/index.ts - Added debug logging
  4. mcp-server/README.md - Added prerequisite documentation
  5. mcp-server/TROUBLESHOOTING.md - New troubleshooting guide