Remote MariaDB direct-query limits

Remote exec_sql and run_sql use MariaDB Connector/C continuation query/fetch calls with mysql_use_result. Socket-read/write waits check the shared remote SQL deadline/steps. Successful queries consume through EOF before freeing the result; discarded exec_sql rows are also consumed and budgeted. Local direct queries keep their existing path.

The client refuses more than 100,000 rows or 64 MiB of conservative cell/row/ field accounting before application copies. On budget, SQL, wait or protocol error, the affected socket is shut down, unread result drain is disabled and that connection closes. Callers must reconnect and must not reuse its old transaction/cursor state. Multiple result sets are refused and close the connection rather than leaving an unread result on a successful connection.

This depends on MariaDB Connector/C’s continuation API, not MySQL’s different async API. Not a process allocator quota: the driver can allocate a giant row before its lengths are inspected. Not confirmed server-side cancellation, server memory/work bounds or rollback of earlier committed commands. Setup, table/navigation/aggregate/write driver calls and retained cursor totals still need separate controls. Coverage is partial.