Name
GC_FILES_TO_LOCKS
Synopsis
Values:See description
Default:Must have identical values
A Parallel Server parameter that controls the mapping of PCM locks to datafiles. GC_FILES_TO_LOCKS should be set to cover as many files as possible. Thus, to avoid performance problems, it should always be changed to correspond to changes in the size of datafiles or to accommodate new datafiles that are added. Changing the parameter requires a shutdown and restart of the parallel server. GC_FILES_TO_LOCKS uses the following syntax:
GC_FILES_TO_LOCKS = "{file_list=lock_count[!blocks][EACH]}[:]..."- file_list
One or more datafiles listed by their file numbers or ranges of file numbers, with comma separators ( filenumber[-filenumber][,filenumber[-filenumber]] ...).
- lock_count
The number of PCM locks assigned to file_list. If lock_count is set to 0, fine-grain locking is used for these files.
- !blocks
Optionally indicates the number of contiguous blocks covered by one lock.
- EACH
Optionally specifies that each datafile in file_list is assigned a separate set of lock_count PCM locks; the default is noncontiguous blocks.
For example:
GC_FILES_TO_LOCKS = "1-4 = 64 EACH : 5-6 = 32 EACH"
If the number of PCM locks allocated to a datafile is less than or equal to the number of blocks contained in a datafile, each of these locks will cover a number of contiguous blocks within the datafile equal to !blocks. If the number of PCM locks assigned to the datafile is larger than the number of blocks it contains, resources will be wasted, since there will be locks that are not covering any blocks. The datafiles not specified in GC_FILES_TO_LOCKS are covered, by default, by releasable locks. These locks are controlled by a different parameter, GC_RELEASABLE_LOCKS.