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.
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:
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 ...