In This Chapter

This chapter describes a new mechanism, called a repack thread, by which empty pages can be removed from a table after moving data with the highest ROWID values to storage locations with lower ROWID values.

This data movement, and the deallocation of extents that no longer contain any data, are supported by the following new features:

• A new REPACK DATA option to the onutil utility.
• A new REPACK_THREAD_MAX configuration parameter can specify the maximum number of repack threads. (Otherwise, the default is 10.)
• A new SET REPACK_THREAD_MAX option to the onutil utility can dynamically reset the REPACK_THREAD_MAX configuration parameter value at run time.
• A new pak option to the onstat utility can display information about each repack thread and the progress of its operation.
• A new log record, PTSHRINK, records repack operations, which user informix can read from the logical logs and display with the onlog utility.