Oracle Partitioning Oracle Tips by Burleson Consulting

Oracle partitioning is a divide-and-conquer approach to improving Oracle maintenance and SQL performance.  Anyone with un-partitioned databases over 500 gigabytes is courting disaster.  Databases become unmanageable, and serious problems occur: 

• SQL may perform poorly - Without Oracle partitioning, SQL queries with full-table scans take hours to complete.  In a full scan, the smaller the Oracle partition, the faster the performance.  Also, index range scans become inefficient.

• Recovery - Files recovery takes days, not minutes

• Maintenance - Rebuilding indexes (important to re-claim space and improve performance)

There are many compelling reasons to implement Oracle partitioning for larger databases, and Oracle partitioning has become the de-facto standard for systems over 500 gigabytes.  Oracle partitioning has many benefits to improve performance and manageability:

• Stable - Oracle partitioning is a very stable technology and has been used in Oracle since Oracle8, back in 1997.  Each new release of Oracle improves Oracle partitioning features.

• Robust ? Oracle partitioning allows for multi-level keys, a combination of the Range and List partitioning technique. The table is first range-partitioned with Oracle partitioning, and then each individual range-partition is further sub-partitioned using a list partitioning technique with Oracle partitioning. Unlike composite Range-Hash Oracle partitioning, the content of each sub-partition represents a logical subset of the data, described by its appropriate Range and List Oracle partition setup. 

• Faster backups - A DBA can back-up a single Oracle partition of a table, rather than backing up the entire table, thereby reducing backup time.

• Less overhead ? Because older Oracle partitioned tablespaces can be marked as read-only, Oracle has less stress on the redo logs, locks and latches, thereby improving overall performance.  For more details, read Robert Freeman's discussion of read-only tablespace performance.

• Easier management ? Maintenance of Oracle partitioned tables is improved because maintenance can be focused on particular portions of tables. For maintenance operations across an entire database object, it is possible to perform these operations on a per-partition basis, thus dividing the maintenance process into more manageable chunks.

• Faster SQL ? Oracle is partition-aware, and some SQL may improve is speed by several orders of magnitude (over 100x faster).

- Index range scans ? Oracle partitioning physically sequences rows in index-order causing a dramatic improvement (over 10x faster) in the speed of partition-key scans.

-  Full-table scans ? Oracle partition pruning only accesses those data blocks required by the query.

-  Table joins ? Oracle partition-wise joins take the specific sub-set of the query partitions, causing huge speed improvements on nested loop and hash joins.

-  Updates ? Oracle parallel query for partitions improves batch load speed.

In sum, Oracle partitioning has a very-fast payback time and the immediate improvements to performance and stress reduction on the Oracle server makes it a slam-dunk decision.

Please see related partitioning pages:

Oracle partitioning methods

oracle partitioning tips

Oracle Partitioning

Oracle interval partitioning tips

Oracle Partition Key Statistics & tuning

 

 

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