Package org.apache.ignite.cache.query.annotations

Annotation Type QuerySqlFunction

  • @Documented
@Retention(RUNTIME)
@Target(METHOD)
public @interface QuerySqlFunction
    Annotates public methods in classes to be used in SQL queries as custom functions. Annotated class must be registered using following method CacheConfiguration.setSqlFunctionClasses(Class[]).

    Example usage: 

         public class MyFunctions {
         @QuerySqlFunction
         public static int sqr(int x) {
             return x * x;
         }
     }

     // Register in CacheConfiguration.
     cacheCfg.setSqlFunctionClasses(MyFunctions.class);

     // And use in queries.
     cache.query(new SqlFieldsQuery("select sqr(2) where sqr(1) = 1"));

    SQL functions can use attributes set on client side: 

         public class MyFunctions {
         @SessionContextProviderResource
         public SessionContextProvider sesCtxProv;

         @QuerySqlFunction
         public String sessionId() {
             return sesCtxProv.getSessionContext().getAttribute("SESSION_ID");
         }
     }
    Note, accessing to the attributes is available in the Calcite query engine only. In a such case a class must have public zero-args constructor.
    See Also:
    QuerySqlTableFunction, SessionContextProviderResource

    • Optional Element Summary

      Optional Elements 
      Modifier and Type Optional Element Description
      String alias
      Specifies alias for the function to be used form SQL queries.
      boolean deterministic
      Specifies if the function is deterministic (result depends only on input parameters).

    • Element Detail

      • alias

        String alias
        Specifies alias for the function to be used form SQL queries. If no alias provided method name will be used.
        Returns:
        Alias for function.
        Default:
        ""

      • deterministic

        boolean deterministic
        Specifies if the function is deterministic (result depends only on input parameters).

        Deterministic function is a function which always returns the same result assuming that input parameters are the same.

        Returns:
        true If function is deterministic, false otherwise.
        Default:
        false