August 2000
Intermediate to advanced
288 pages
7h 50m
English
Content preview from Oracle Parallel ProcessingBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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PCM Lock Allocation Parameters and Verification
There are three initialization parameters that control the allocation of PCM locks in an OPS environment:
- GC_FILES_TO_LOCKS
Controls PCM lock allocation to datafiles. The value of this parameter must be the same for all instances of an OPS database.
- GC_RELEASABLE_LOCKS
Allocates releasable locks. The value of this parameter may be different for each instance of an OPS database.
- GC_ROLLBACK_LOCKS
Specifies the number of locks available for each rollback segment that is being modified concurrently. The value of this parameter must be the same for all instances of an OPS database.
The following sections describe these parameters, how you can use them to best advantage, and how you can verify lock allocation.
The GC_FILES_TO_LOCKS Parameter
This parameter specifies the manner in which PCM locks are allocated to different datafiles. It specifies the number of locks allocated to a specific file, and/or to a set of datafiles, except for those files that contain rollback segments. The GC_ROLLBACK_LOCKS parameter is used to allocate locks to files with rollback segments.
GC_FILES_TO_LOCKS syntax
The syntax for the GC_FILES_TO_LOCKS parameter is rather complex and looks like this:
GC_FILES_TO_LOCKS = "LOCK_ALLOCATION[:LOCK_ALLOCATION...]" LOCK_ALLOCATION := FILE_LIST=num_locks[!blocking][R][EACH] FILE_LIST :=fileid[-fileid][,fileid[-fileid]...]
- LOCK_ALLOCATION
Allocates a specific number of locks to one or more files. Multiple LOCK_ALLOCATION entries are ...
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