papers/lux-gchain-graphql/sections/07-on-chain-query-execution.tex

\section{On-Chain Query Execution}


\subsection{Gas-Metered GraphVM}

Smart contracts can execute GraphQL queries through precompiles:

\begin{lstlisting}[language=Solidity, basicstyle=\small\ttfamily]
interface IGChainQuery {
    // Execute compiled query bytecode
    function executeQuery(
        bytes calldata queryBytecode,
        bytes calldata params
    ) external view returns (bytes memory result);
    
    // Register persistent query
    function registerQuery(
        string calldata name,
        bytes calldata queryBytecode
    ) external returns (bytes32 queryId);
    
    // Execute registered query
    function executeRegistered(
        bytes32 queryId,
        bytes calldata params
    ) external view returns (bytes memory result);
}
\end{lstlisting}

\subsection{Example: On-Chain Portfolio Valuation}

\begin{lstlisting}[language=Solidity, basicstyle=\small\ttfamily]
contract PortfolioManager {
    IGChainQuery gchain;
    
    function getUserTVL(address user) external view returns (uint256) {
        // Query cross-chain balances
        bytes memory query = compileQuery(
            "query($user: Address!) { "
            "  addressBalances(address: $user) { "
            "    valueUSD "
            "  } "
            "}"
        );
        
        bytes memory params = abi.encode(user);
        bytes memory result = gchain.executeQuery(query, params);
        
        // Parse result
        uint256 totalUSD = 0;
        uint256[] memory balances = abi.decode(result, (uint256[]));
        for (uint i = 0; i < balances.length; i++) {
            totalUSD += balances[i];
        }
        
        return totalUSD;
    }
}
\end{lstlisting}