New "pivot" SQL clause - The new "pivot" SQL clause will allow quick rollup, similar to an MS-Excel pivot table, where you can display multiple rows on one column with SQL.
MS SQL Server 2005 also introduced a pivot clause. Laurent Schneider notes that the new SQL "pivot" syntax is great for converting rows-to-columns and columns-to-rows.
The /*+result_cache*/ SQL hint - This suggests that the result data will be cached in the data buffers, and not the intermediate data blocks that were accessed to obtain the query results. You can cache SQL and PL/SQL results for super-fast subsequent retrieval. The "result cache" ties into the "scalable execution" concept.
There are three areas of the result cache:
The SQL query result cache - This is an area of SGA memory for storing query results.
The PL/SQL function result cache - This result cache can store the results from a PL/SQL function call.
The OCI client result cache - This cache retains results from OCI calls, both for SQL queries or PL/SQL functions.
Scalable Execution - This 11g feature consists of a number of features, the first of which is query results caching; this feature automatically caches the results of an SQL query as opposed to the data blocks normally cached by the buffer cache, and works both client (OCI) and server side - this was described as "buffer cache taken to the next level". The DBA sets the size of the results cache and turns the feature on at a table level with the command "alter table DEPT cache results", the per-process cache is shared across multiple session and at the client level, is available with all 11g OCI-based clients.
XML SQL queries - Oracle11g will support query mechanisms for XML including XQuery and SQL XML, emerging standards for querying XML data stored inside tables.
SQL Replay - Similar to the previous feature, but this only captures and applies the SQL workload, not total workload.
Improved optimizer statistics collection speed - Oracle 11g has improved the dbms_stats performance, allowing for an order of magnitude faster CBO statistics creation. Oracle 11g has also separated-out the "gather" and "publish" operations, allowing CBO statistics to be retained for later use. Also, Oracle 11g introduces multi-column statistics to give the CBO the ability to more accurately select rows when the WHERE clause contains multi-column conditions or joins.
SQL execution Plan Management - Oracle 11g SQL will allow you to fix execution plans (explain plan) for specific statements, regardless of statistics or database version changes. See Inside the 11g SQL Performance Advisor.
Dynamic SQL. DBMS_SQL is here to stay. It's faster and is being enhanced. DBMS_SQL and NDS can now accept CLOBs (no more 32k limit on NDS). A ref cursor can become a DBMS_SQL cursor and vice versa. DBMS_SQL now supprts user defined types and bulk operations.
SQL Performance Advisor - You can tell 11g to automatically apply SQL profiles for statements where the suggested profile give 3-times better performance that the existing statement. The performance comparisons are done by a new administrative task during a user-specified maintenance window.
Improved SQL Access Advisor - The 11g SQL Access Advisor gives partitioning advice, including advice on the new interval partitioning. Interval partitioning is an automated version of range partitioning, where new equally-sized partitions are automatically created when needed. Both range and interval partitions can exist for a single table, and range partitioned tables can be converted to interval partitioned tables.