Oracle Parallel Processing

Chapter 9. Storage Management in OPS

Storage management is an important aspect of database tuning. Oracle manages storage space using several storage management parameters. You can use some of these storage management parameters—in particular, FREELISTS, FREELIST GROUP, and PCTFREE—to improve the performance of Oracle Parallel Server. This chapter explains the concepts behind these parameters and describes how to set them in an OPS environment.

In this chapter we also discuss Oracle’s reverse key index feature, which you can use to spread the index entries in an index tree more evenly when the indexes are based on sequential keys. Use of reverse key indexes can reduce contention for index leaf blocks during index updates when many instances are inserting rows into the same table.

Using Free Lists and Free List Groups

Free lists and free list groups are structures that Oracle uses to keep track of the free space within a segment such as a table, index, or cluster. If you have a large number of processes updating or inserting data into a segment, they will all need access to the segment’s free list. Too much contention for a segment’s free list can cause performance to suffer. The FREELISTS and FREELIST GROUP space management parameters are used to reduce contention for a segment’s free list as follows:

FREELISTS

You can set this parameter in both OPS and non-OPS environments. Use it to reduce contention for free lists when multiple-user processes are inserting or updating the same ...