Optimize Distributed Workload - Expert Oracle RAC Performance Diagnostics and Tuning - page 530

SELECT inst_id INT,
parameter,
dlm_requests requests,
dlm_conflicts conflicts,
dlm_releases releases
FROM gv$rowcache
WHERE dlm_requests > 1000
ORDER BY inst_id,
dlm_requests desc,
dlm_conflicts desc;
INT PARAMETER REQUESTS CONFLICTS RELEASES
---- ---------------------- -------- --------- --------
1 dc_sequences 1107598 126029 0
dc_histogram_defs 6304 45 0
dc_objects 3604 27 0
dc_segments 2704 92 0
2 dc_sequences 1120159 126024 0
dc_histogram_defs 5361 0 0
dc_objects 3425 6 0
dc_segments 2999 75 0
dc_rollback_segments 2442 170 0
Step 9
Increasing the cache size to a higher number to reduce the number of get misses increases the percentage of
successful gets:
ALTER SEQUENCE INST_FILE_UPLOAD_SEQ CACHE SIZE 4000;
INDeX LeaF BLOCKS
initially each index tree has one level. if the data in the table is very small, there may be only one index block.
in that case, the leaf block is the same as the branch block (Figure 15-5 ). as the data grows, the level increases;
and then there is a branch block and a leaf block with a parent-child relationship. the maximum number of levels
that the b-tree index can grow to is 24 (i.e., 0-23), which means that with two rows per index block, it can hold
approximately 18 billion leaf blocks.