Oracle 11i new features

1. PL/SQL native compilation. In oracle 10g, there is an option to compile pl/sql with c compiler and so it can execute directly without interpretion, but it needs a c compiler on your system. In oracle 11i, it actually can compile pl/sql in a native way without the needs of a local c compiler. One initialization parameter, plsql_code_type, can be set to be either native or interpreted to change the way pl/sql is compiled.
2. Adaptive cursor sharing. You can set cursor_sharing parameter to be 'similar' to make oracle parsing to share parsing plan between similar queries. But the problem is when data are skewed. The execution plan used for one value may not be good for another value at all. What oracle 11i does now is that it has a few excution plans for a query, when it finds one plan is too expensive, then it will start to look at others.
3 Server result cache, which is actually part of the shared pool in the SGA. the initialization parameter result_cache_max_size is the one to setup the size. New package DBMS_RESULT_CACHE provides various procedurs to aminister the result cache feature. v$result_cache_* views are the place to look at the success of a cached SQL query or a PL/SQL function by determining the cache-hit scucess of the query of function.