Oracle Partitioning

Starting in Oracle9i we see several important Oracle partitioning strategies, all designed to provide the best-fit for your SQL queries to minimize I/O:

• Range Partitioning - Used when there are logical ranges of data. Possible usage: dates, part numbers, and serial numbers.

• Hash Partitioning - Used to spread data evenly over partitions. Possible usage: data has no logical groupings.

• List Partitioning - Used to list together unrelated data into partitions. Possible usage: a number of states list partitioned into a region.

• Composite Range-Hash Partitioning - Used to range partition first, then spreads data into hash partitions. Possible usage: range partition by date of birth then hash partition by name; store the results into the hash partitions.

• Composite Range-List Partitioning - Used to range partition first, then spreads data into list partitions.  Possible usage: range partition by date of birth then list partition by state, then store the results into the list partitions.

Oracle 10g partitioning allows for easier DBA management and the 10g partition-aware SQL will result in improved SQL performance.

As of 11g, we saw these new partitioning features.  For full details, see the book Oracle 11g New Features: Expert Guide to the Important New Features by John Garmany, Steve Karam, Lutz Hartmann, V. J. Jain and Brian Carr.

• Interval partitioning for tables - This is a new 11g partitioning scheme that automatically creates time-based partitions as new data is added. You can now partition by date, one partition per month for example, with automatic partition creation. Interval partitions build upon the foundation introduced with range partitioning for Oracle 11g. Interval   partitioning resolves the limitations built into range partitioning when a specific range is unknown by the  developer or DBA creating the partitions for the table. It tells Oracle to automatically setup new  partitions for a particular interval when data inserted to tables are greater than the range partitions. As  such the requirement of interval partitioning dictates that at least one range partition is specified. Once  the range partitioning key is given for the high value of the range partitions, this transition point is used  as the baseline to create interval partitions beyond this point.
  

• System Partitioning - The new system partitioning feature in Oracle 11g provides you with the ability to implement and manage new partitions without a specific partition key. Instead, each partition is mapped to a tablespace using the extended partitioning syntax for system partitions. Due to lack of partition keys with system partitioning, the usual performance benefits available for partitioned tables do not exist with system partitions. Another drawback to system partitions is that they cannot be used for partition-wise joins or traditional partition pruning operations. As such, the main benefit of using the new system partitioning is for manageability purposes.  Also see these notes on system partitioning in 11g.