Measuring Fragmentation

You can measure fragmentation using the average fragmentation quotient statistic. In ESSCMD, look at the Average Fragmentation Quotient that is returned when you execute the GETDBSTATS command. Use the information in Table 168 to evaluate whether the level likely will cause performance problems:

Table 168. Measuring Fragmentation Thresholds Using the Average Fragmentation Quotient

Database Size

Fragmentation Quotient Threshold

Small (<200 MB)

60% or greater

Medium (<2 GB)

40% or greater

Large (>2 GB)

30% or greater

Any quotient above the high end of the range indicates that reducing fragmentation may help performance, with the following qualifications:

The average clustering ratio database statistic is an approximate indication of the ordering in which data blocks are laid out in data (.pag) files. The maximum value of 1 indicates that the blocks are laid out in block key order within data files. The reported value of the clustering ratio may be less than 1, even upon restructure, due to the scalability enhancements as well as support for parallel operations.

  To view fragmentation statistics for a database, use a tool:

Tool

Topic

Location

Administration Services

Viewing Fragmentation Statistics

Oracle Essbase Administration Services Online Help

ESSCMD

GETDBSTATS

Oracle Essbase Technical Reference

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