You can generate three types of reports with dbcc tablealloc or dbcc indexalloc:
full – produces a report containing all types of allocation errors. Using the full option with dbcc tablealloc gives the same results as using dbcc checkalloc at a table level.
optimized – produces a report based on the allocation pages listed in the OAM pages for the table. When you use the optimized option, dbcc tablealloc does not report and cannot fix unreferenced extents on allocation pages that are not listed in the OAM pages. If you do not specify a report type, or if you specify null, optimized is the default.
fast – produces an exception report of pages that are referenced but not allocated in the extent (2521-level errors); does not produce an allocation report.
For a comparison of speed, completeness, locking, and performance issues for these options and other dbcc commands, see Table 25-2.
