Redis MCP Server

Instructions

Implementation Reference

• src/tools/misc.py:159-200 (handler)

  The handler function for the 'scan_all_keys' MCP tool. It performs iterative SCAN operations on Redis to retrieve all keys matching the given pattern, handling cursor management and byte decoding internally. The @mcp.tool() decorator registers the tool.

  @mcp.tool()
  async def scan_all_keys(
      pattern: str = "*", batch_size: int = 100
  ) -> Union[str, List[str]]:
      """
      Scan and return ALL keys matching a pattern using multiple SCAN iterations.
  
      This function automatically handles the SCAN cursor iteration to collect all matching keys.
      It's safer than KEYS * for large databases but will still collect all results in memory.
  
      ⚠️  WARNING: With very large datasets (millions of keys), this may consume significant memory.
      For large-scale operations, consider using scan_keys() with manual iteration instead.
  
      Args:
          pattern: Pattern to match keys against (default is "*" for all keys).
          batch_size: Number of keys to scan per iteration (default 100).
  
      Returns:
          A list of all keys matching the pattern or an error message.
      """
      try:
          r = RedisConnectionManager.get_connection()
          all_keys = []
          cursor = 0
  
          while True:
              cursor, keys = r.scan(cursor=cursor, match=pattern, count=batch_size)
  
              # Convert bytes to strings if needed and add to results
              decoded_keys = [
                  key.decode("utf-8") if isinstance(key, bytes) else key for key in keys
              ]
              all_keys.extend(decoded_keys)
  
              # Break when scan is complete (cursor returns to 0)
              if cursor == 0:
                  break
  
          return all_keys
      except RedisError as e:
          return f"Error scanning all keys with pattern '{pattern}': {str(e)}"