Optimizer directives

IBM® Informix® SQL allows you to specify query optimization directives to force the query optimizer to use a different path than the implicit plan. With IBM Informix, optimizer directives are specified with the following SQL comment markers followed by a plus sign:

/*+ optimizer-directives */
{+  optimizer-directives }
--+ optimizer-directives

Genero BDL partially supports optimizer directives:

Tip: Optimization directives are not portable. If you plan to use different types of database servers, you should avoid the usage of query plan hints.